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  • Weekend Entity Framework Class in Dallas...

    - by [email protected]
    Zeeshan Nirani, MVP in the Data Programability Group, co-author of the upcoming Entity Framework Recipies book, is teaching a 6 week class on Entity Framework 4.0 at Collin Community College, beginning May 22nd. The class will meet each Saturday morning from 9 am to 1. There is probably nobody in the Metroplex area that knows the Entity Framework as initimately as Zeeshan. Go and sign-up for this course NOW and consider yourself lucky to have the opportunity to attend. You WILL learn the Entity Framework which will be CRITICAL to your success in Microsoft development, as MSFT has made this framework one of their core pieces moving forward.   Contact Zeeshan at [email protected] for more details.      

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  • Processing component pools problem - Entity Subsystem

    - by mani3xis
    Architecture description I'm creating (designing) an entity system and I ran into many problems. I'm trying to keep it Data-Oriented and efficient as much as possible. My components are POD structures (array of bytes to be precise) allocated in homogeneous pools. Each pool has a ComponentDescriptor - it just contains component name, field types and field names. Entity is just a pointer to array of components (where address acts like an entity ID). EntityPrototype contains entity name and array of component names. Finally Subsystem (System or Processor) which works on component pools. Actual problem The problem is that some components dependents on others (Model, Sprite, PhysicalBody, Animation depends on Transform component) which makes a lot of problems when it comes to processing them. For example, lets define some entities using [S]prite, [P]hysicalBody and [H]ealth: Tank: Transform, Sprite, PhysicalBody BgTree: Transform, Sprite House: Transform, Sprite, Health and create 4 Tanks, 5 BgTrees and 2 Houses and my pools will look like: TTTTTTTTTTT // Transform pool SSSSSSSSSSS // Sprite pool PPPP // PhysicalBody pool HH // Health component There is no way to process them using indices. I spend 3 days working on it and I still don't have any ideas. In previous designs TransformComponent was bound to the entity - but it wasn't a good idea. Can you give me some advices how to process them? Or maybe I should change the overall design? Maybe I should create pools of entites (pools of component pools) - but I guess it will be a nightmare for CPU caches. Thanks

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  • How to update entity states and animations in a component-based game

    - by mivic
    I'm trying to design a component-based entity system for learning purposes (and later use on some games) and I'm having some troubles when it comes to updating entity states. I don't want to have an update() method inside the Component to prevent dependencies between Components. What I currently have in mind is that components hold data and systems update components. So, if I have a simple 2D game with some entities (e.g. player, enemy1, enemy 2) that have Transform, Movement, State, Animation and Rendering components I think I should have: A MovementSystem that moves all the Movement components and updates the State components And a RenderSystem that updates the Animation components (the animation component should have one animation (i.e. a set of frames/textures) for each state and updating it means selecting the animation corresponding to the current state (e.g. jumping, moving_left, etc), and updating the frame index). Then, the RenderSystem updates the Render components with the texture corresponding to the current frame of each entity's Animation and renders everything on screen. I've seen some implementations like Artemis framework, but I don't know how to solve this situation: Let's say that my game has the following entities. Each entity have a set of states and one animation for each state: player: "idle", "moving_right", "jumping" enemy1: "moving_up", "moving_down" enemy2: "moving_left", "moving_right" What are the most accepted approaches in order to update the current state of each entity? The only thing that I can think of is having separate systems for each group of entities and separate State and Animation components so I would have PlayerState, PlayerAnimation, Enemy1State, Enemy1Animation... PlayerMovementSystem, PlayerRenderingSystem... but I think this is a bad solution and breaks the purpose of having a component-based system. As you can see, I'm quite lost here, so I'd very much appreciate any help.

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  • Open source Entity-Component game [on hold]

    - by Papavoikos
    I've been reading a lot about entity-component design but every article talks about the philosophy behind such design, leaving a lot of details and implementations outside. I'm looking for an open source game that uses the entity-component design so I can study the concrete implementations and see how they deal with things such as How (and if) they deal with inter-component communication How much logic each component has or doesn't have How a subsystem can change it's behavior depending on an entity's state (the screen darkens depending on the player's health)

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  • Waterfall Model (SDLC) vs. Prototyping Model

    The characters in the fable of the Tortoise and the Hare can easily be used to demonstrate the similarities and differences between the Waterfall and Prototyping software development models. This children fable is about a race between a consistently slow moving but steadfast turtle and an extremely fast but unreliable rabbit. After closely comparing each character’s attributes in correlation with both software development models, a trend seems to appear in that the Waterfall closely resembles the Tortoise in that Waterfall Model is typically a slow moving process that is broken up in to multiple sequential steps that must be executed in a standard linear pattern. The Tortoise can be quoted several times in the story saying “Slow and steady wins the race.” This is the perfect mantra for the Waterfall Model in that this model is seen as a cumbersome and slow moving. Waterfall Model Phases Requirement Analysis & Definition This phase focuses on defining requirements for a project that is to be developed and determining if the project is even feasible. Requirements are collected by analyzing existing systems and functionality in correlation with the needs of the business and the desires of the end users. The desired output for this phase is a list of specific requirements from the business that are to be designed and implemented in the subsequent steps. In addition this phase is used to determine if any value will be gained by completing the project. System Design This phase focuses primarily on the actual architectural design of a system, and how it will interact within itself and with other existing applications. Projects at this level should be viewed at a high level so that actual implementation details are decided in the implementation phase. However major environmental decision like hardware and platform decision are typically decided in this phase. Furthermore the basic goal of this phase is to design an application at the system level in those classes, interfaces, and interactions are defined. Additionally decisions about scalability, distribution and reliability should also be considered for all decisions. The desired output for this phase is a functional  design document that states all of the architectural decisions that have been made in regards to the project as well as a diagrams like a sequence and class diagrams. Software Design This phase focuses primarily on the refining of the decisions found in the functional design document. Classes and interfaces are further broken down in to logical modules based on the interfaces and interactions previously indicated. The output of this phase is a formal design document. Implementation / Coding This phase focuses primarily on implementing the previously defined modules in to units of code. These units are developed independently are intergraded as the system is put together as part of a whole system. Software Integration & Verification This phase primarily focuses on testing each of the units of code developed as well as testing the system as a whole. There are basic types of testing at this phase and they include: Unit Test and Integration Test. Unit Test are built to test the functionality of a code unit to ensure that it preforms its desired task. Integration testing test the system as a whole because it focuses on results of combining specific units of code and validating it against expected results. The output of this phase is a test plan that includes test with expected results and actual results. System Verification This phase primarily focuses on testing the system as a whole in regards to the list of project requirements and desired operating environment. Operation & Maintenance his phase primarily focuses on handing off the competed project over to the customer so that they can verify that all of their requirements have been met based on their original requirements. This phase will also validate the correctness of their requirements and if any changed need to be made. In addition, any problems not resolved in the previous phase will be handled in this section. The Waterfall Model’s linear and sequential methodology does offer a project certain advantages and disadvantages. Advantages of the Waterfall Model Simplistic to implement and execute for projects and/or company wide Limited demand on resources Large emphasis on documentation Disadvantages of the Waterfall Model Completed phases cannot be revisited regardless if issues arise within a project Accurate requirement are never gather prior to the completion of the requirement phase due to the lack of clarification in regards to client’s desires. Small changes or errors that arise in applications may cause additional problems The client cannot change any requirements once the requirements phase has been completed leaving them no options for changes as they see their requirements changes as the customers desires change. Excess documentation Phases are cumbersome and slow moving Learn more about the Major Process in the Sofware Development Life Cycle and Waterfall Model. Conversely, the Hare shares similar traits with the prototyping software development model in that ideas are rapidly converted to basic working examples and subsequent changes are made to quickly align the project with customers desires as they are formulated and as software strays from the customers vision. The basic concept of prototyping is to eliminate the use of well-defined project requirements. Projects are allowed to grow as the customer needs and request grow. Projects are initially designed according to basic requirements and are refined as requirement become more refined. This process allows customer to feel their way around the application to ensure that they are developing exactly what they want in the application This model also works well for determining the feasibility of certain approaches in regards to an application. Prototypes allow for quickly developing examples of implementing specific functionality based on certain techniques. Advantages of Prototyping Active participation from users and customers Allows customers to change their mind in specifying requirements Customers get a better understanding of the system as it is developed Earlier bug/error detection Promotes communication with customers Prototype could be used as final production Reduced time needed to develop applications compared to the Waterfall method Disadvantages of Prototyping Promotes constantly redefining project requirements that cause major system rewrites Potential for increased complexity of a system as scope of the system expands Customer could believe the prototype as the working version. Implementation compromises could increase the complexity when applying updates and or application fixes When companies trying to decide between the Waterfall model and Prototype model they need to evaluate the benefits and disadvantages for both models. Typically smaller companies or projects that have major time constraints typically head for more of a Prototype model approach because it can reduce the time needed to complete the project because there is more of a focus on building a project and less on defining requirements and scope prior to the start of a project. On the other hand, Companies with well-defined requirements and time allowed to generate proper documentation should steer towards more of a waterfall model because they are in a position to obtain clarified requirements and have to design and optimal solution prior to the start of coding on a project.

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  • Entity Association Mapping with Code First Part 1 : Mapping Complex Types

    - by mortezam
    Last week the CTP5 build of the new Entity Framework Code First has been released by data team at Microsoft. Entity Framework Code-First provides a pretty powerful code-centric way to work with the databases. When it comes to associations, it brings ultimate flexibility. I’m a big fan of the EF Code First approach and am planning to explain association mapping with code first in a series of blog posts and this one is dedicated to Complex Types. If you are new to Code First approach, you can find a great walkthrough here. In order to build a solid foundation for our discussion, we will start by learning about some of the core concepts around the relationship mapping.   What is Mapping?Mapping is the act of determining how objects and their relationships are persisted in permanent data storage, in our case, relational databases. What is Relationship mapping?A mapping that describes how to persist a relationship (association, aggregation, or composition) between two or more objects. Types of RelationshipsThere are two categories of object relationships that we need to be concerned with when mapping associations. The first category is based on multiplicity and it includes three types: One-to-one relationships: This is a relationship where the maximums of each of its multiplicities is one. One-to-many relationships: Also known as a many-to-one relationship, this occurs when the maximum of one multiplicity is one and the other is greater than one. Many-to-many relationships: This is a relationship where the maximum of both multiplicities is greater than one. The second category is based on directionality and it contains two types: Uni-directional relationships: when an object knows about the object(s) it is related to but the other object(s) do not know of the original object. To put this in EF terminology, when a navigation property exists only on one of the association ends and not on the both. Bi-directional relationships: When the objects on both end of the relationship know of each other (i.e. a navigation property defined on both ends). How Object Relationships Are Implemented in POCO domain models?When the multiplicity is one (e.g. 0..1 or 1) the relationship is implemented by defining a navigation property that reference the other object (e.g. an Address property on User class). When the multiplicity is many (e.g. 0..*, 1..*) the relationship is implemented via an ICollection of the type of other object. How Relational Database Relationships Are Implemented? Relationships in relational databases are maintained through the use of Foreign Keys. A foreign key is a data attribute(s) that appears in one table and must be the primary key or other candidate key in another table. With a one-to-one relationship the foreign key needs to be implemented by one of the tables. To implement a one-to-many relationship we implement a foreign key from the “one table” to the “many table”. We could also choose to implement a one-to-many relationship via an associative table (aka Join table), effectively making it a many-to-many relationship. Introducing the ModelNow, let's review the model that we are going to use in order to implement Complex Type with Code First. It's a simple object model which consist of two classes: User and Address. Each user could have one billing address. The Address information of a User is modeled as a separate class as you can see in the UML model below: In object-modeling terms, this association is a kind of aggregation—a part-of relationship. Aggregation is a strong form of association; it has some additional semantics with regard to the lifecycle of objects. In this case, we have an even stronger form, composition, where the lifecycle of the part is fully dependent upon the lifecycle of the whole. Fine-grained domain models The motivation behind this design was to achieve Fine-grained domain models. In crude terms, fine-grained means “more classes than tables”. For example, a user may have both a billing address and a home address. In the database, you may have a single User table with the columns BillingStreet, BillingCity, and BillingPostalCode along with HomeStreet, HomeCity, and HomePostalCode. There are good reasons to use this somewhat denormalized relational model (performance, for one). In our object model, we can use the same approach, representing the two addresses as six string-valued properties of the User class. But it’s much better to model this using an Address class, where User has the BillingAddress and HomeAddress properties. This object model achieves improved cohesion and greater code reuse and is more understandable. Complex Types: Splitting a Table Across Multiple Types Back to our model, there is no difference between this composition and other weaker styles of association when it comes to the actual C# implementation. But in the context of ORM, there is a big difference: A composed class is often a candidate Complex Type. But C# has no concept of composition—a class or property can’t be marked as a composition. The only difference is the object identifier: a complex type has no individual identity (i.e. no AddressId defined on Address class) which make sense because when it comes to the database everything is going to be saved into one single table. How to implement a Complex Types with Code First Code First has a concept of Complex Type Discovery that works based on a set of Conventions. The convention is that if Code First discovers a class where a primary key cannot be inferred, and no primary key is registered through Data Annotations or the fluent API, then the type will be automatically registered as a complex type. Complex type detection also requires that the type does not have properties that reference entity types (i.e. all the properties must be scalar types) and is not referenced from a collection property on another type. Here is the implementation: public class User{    public int UserId { get; set; }    public string FirstName { get; set; }    public string LastName { get; set; }    public string Username { get; set; }    public Address Address { get; set; }} public class Address {     public string Street { get; set; }     public string City { get; set; }            public string PostalCode { get; set; }        }public class EntityMappingContext : DbContext {     public DbSet<User> Users { get; set; }        } With code first, this is all of the code we need to write to create a complex type, we do not need to configure any additional database schema mapping information through Data Annotations or the fluent API. Database SchemaThe mapping result for this object model is as follows: Limitations of this mappingThere are two important limitations to classes mapped as Complex Types: Shared references is not possible: The Address Complex Type doesn’t have its own database identity (primary key) and so can’t be referred to by any object other than the containing instance of User (e.g. a Shipping class that also needs to reference the same User Address). No elegant way to represent a null reference There is no elegant way to represent a null reference to an Address. When reading from database, EF Code First always initialize Address object even if values in all mapped columns of the complex type are null. This means that if you store a complex type object with all null property values, EF Code First returns a initialized complex type when the owning entity object is retrieved from the database. SummaryIn this post we learned about fine-grained domain models which complex type is just one example of it. Fine-grained is fully supported by EF Code First and is known as the most important requirement for a rich domain model. Complex type is usually the simplest way to represent one-to-one relationships and because the lifecycle is almost always dependent in such a case, it’s either an aggregation or a composition in UML. In the next posts we will revisit the same domain model and will learn about other ways to map a one-to-one association that does not have the limitations of the complex types. References ADO.NET team blog Mapping Objects to Relational Databases Java Persistence with Hibernate

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  • AngularJS on top of ASP.NET: Moving the MVC framework out to the browser

    - by Varun Chatterji
    Heavily drawing inspiration from Ruby on Rails, MVC4’s convention over configuration model of development soon became the Holy Grail of .NET web development. The MVC model brought with it the goodness of proper separation of concerns between business logic, data, and the presentation logic. However, the MVC paradigm, was still one in which server side .NET code could be mixed with presentation code. The Razor templating engine, though cleaner than its predecessors, still encouraged and allowed you to mix .NET server side code with presentation logic. Thus, for example, if the developer required a certain <div> tag to be shown if a particular variable ShowDiv was true in the View’s model, the code could look like the following: Fig 1: To show a div or not. Server side .NET code is used in the View Mixing .NET code with HTML in views can soon get very messy. Wouldn’t it be nice if the presentation layer (HTML) could be pure HTML? Also, in the ASP.NET MVC model, some of the business logic invariably resides in the controller. It is tempting to use an anti­pattern like the one shown above to control whether a div should be shown or not. However, best practice would indicate that the Controller should not be aware of the div. The ShowDiv variable in the model should not exist. A controller should ideally, only be used to do the plumbing of getting the data populated in the model and nothing else. The view (ideally pure HTML) should render the presentation layer based on the model. In this article we will see how Angular JS, a new JavaScript framework by Google can be used effectively to build web applications where: 1. Views are pure HTML 2. Controllers (in the server sense) are pure REST based API calls 3. The presentation layer is loaded as needed from partial HTML only files. What is MVVM? MVVM short for Model View View Model is a new paradigm in web development. In this paradigm, the Model and View stuff exists on the client side through javascript instead of being processed on the server through postbacks. These frameworks are JavaScript frameworks that facilitate the clear separation of the “frontend” or the data rendering logic from the “backend” which is typically just a REST based API that loads and processes data through a resource model. The frameworks are called MVVM as a change to the Model (through javascript) gets reflected in the view immediately i.e. Model > View. Also, a change on the view (through manual input) gets reflected in the model immediately i.e. View > Model. The following figure shows this conceptually (comments are shown in red): Fig 2: Demonstration of MVVM in action In Fig 2, two text boxes are bound to the same variable model.myInt. Thus, changing the view manually (changing one text box through keyboard input) also changes the other textbox in real time demonstrating V > M property of a MVVM framework. Furthermore, clicking the button adds 1 to the value of model.myInt thus changing the model through JavaScript. This immediately updates the view (the value in the two textboxes) thus demonstrating the M > V property of a MVVM framework. Thus we see that the model in a MVVM JavaScript framework can be regarded as “the single source of truth“. This is an important concept. Angular is one such MVVM framework. We shall use it to build a simple app that sends SMS messages to a particular number. Application, Routes, Views, Controllers, Scope and Models Angular can be used in many ways to construct web applications. For this article, we shall only focus on building Single Page Applications (SPAs). Many of the approaches we will follow in this article have alternatives. It is beyond the scope of this article to explain every nuance in detail but we shall try to touch upon the basic concepts and end up with a working application that can be used to send SMS messages using Sent.ly Plus (a service that is itself built using Angular). Before you read on, we would like to urge you to forget what you know about Models, Views, Controllers and Routes in the ASP.NET MVC4 framework. All these words have different meanings in the Angular world. Whenever these words are used in this article, they will refer to Angular concepts and not ASP.NET MVC4 concepts. The following figure shows the skeleton of the root page of an SPA: Fig 3: The skeleton of a SPA The skeleton of the application is based on the Bootstrap starter template which can be found at: http://getbootstrap.com/examples/starter­template/ Apart from loading the Angular, jQuery and Bootstrap JavaScript libraries, it also loads our custom scripts /app/js/controllers.js /app/js/app.js These scripts define the routes, views and controllers which we shall come to in a moment. Application Notice that the body tag (Fig. 3) has an extra attribute: ng­app=”smsApp” Providing this tag “bootstraps” our single page application. It tells Angular to load a “module” called smsApp. This “module” is defined /app/js/app.js angular.module('smsApp', ['smsApp.controllers', function () {}]) Fig 4: The definition of our application module The line shows above, declares a module called smsApp. It also declares that this module “depends” on another module called “smsApp.controllers”. The smsApp.controllers module will contain all the controllers for our SPA. Routing and Views Notice that in the Navbar (in Fig 3) we have included two hyperlinks to: “#/app” “#/help” This is how Angular handles routing. Since the URLs start with “#”, they are actually just bookmarks (and not server side resources). However, our route definition (in /app/js/app.js) gives these URLs a special meaning within the Angular framework. angular.module('smsApp', ['smsApp.controllers', function () { }]) //Configure the routes .config(['$routeProvider', function ($routeProvider) { $routeProvider.when('/binding', { templateUrl: '/app/partials/bindingexample.html', controller: 'BindingController' }); }]); Fig 5: The definition of a route with an associated partial view and controller As we can see from the previous code sample, we are using the $routeProvider object in the configuration of our smsApp module. Notice how the code “asks for” the $routeProvider object by specifying it as a dependency in the [] braces and then defining a function that accepts it as a parameter. This is known as dependency injection. Please refer to the following link if you want to delve into this topic: http://docs.angularjs.org/guide/di What the above code snippet is doing is that it is telling Angular that when the URL is “#/binding”, then it should load the HTML snippet (“partial view”) found at /app/partials/bindingexample.html. Also, for this URL, Angular should load the controller called “BindingController”. We have also marked the div with the class “container” (in Fig 3) with the ng­view attribute. This attribute tells Angular that views (partial HTML pages) defined in the routes will be loaded within this div. You can see that the Angular JavaScript framework, unlike many other frameworks, works purely by extending HTML tags and attributes. It also allows you to extend HTML with your own tags and attributes (through directives) if you so desire, you can find out more about directives at the following URL: http://www.codeproject.com/Articles/607873/Extending­HTML­with­AngularJS­Directives Controllers and Models We have seen how we define what views and controllers should be loaded for a particular route. Let us now consider how controllers are defined. Our controllers are defined in the file /app/js/controllers.js. The following snippet shows the definition of the “BindingController” which is loaded when we hit the URL http://localhost:port/index.html#/binding (as we have defined in the route earlier as shown in Fig 5). Remember that we had defined that our application module “smsApp” depends on the “smsApp.controllers” module (see Fig 4). The code snippet below shows how the “BindingController” defined in the route shown in Fig 5 is defined in the module smsApp.controllers: angular.module('smsApp.controllers', [function () { }]) .controller('BindingController', ['$scope', function ($scope) { $scope.model = {}; $scope.model.myInt = 6; $scope.addOne = function () { $scope.model.myInt++; } }]); Fig 6: The definition of a controller in the “smsApp.controllers” module. The pieces are falling in place! Remember Fig.2? That was the code of a partial view that was loaded within the container div of the skeleton SPA shown in Fig 3. The route definition shown in Fig 5 also defined that the controller called “BindingController” (shown in Fig 6.) was loaded when we loaded the URL: http://localhost:22544/index.html#/binding The button in Fig 2 was marked with the attribute ng­click=”addOne()” which added 1 to the value of model.myInt. In Fig 6, we can see that this function is actually defined in the “BindingController”. Scope We can see from Fig 6, that in the definition of “BindingController”, we defined a dependency on $scope and then, as usual, defined a function which “asks for” $scope as per the dependency injection pattern. So what is $scope? Any guesses? As you might have guessed a scope is a particular “address space” where variables and functions may be defined. This has a similar meaning to scope in a programming language like C#. Model: The Scope is not the Model It is tempting to assign variables in the scope directly. For example, we could have defined myInt as $scope.myInt = 6 in Fig 6 instead of $scope.model.myInt = 6. The reason why this is a bad idea is that scope in hierarchical in Angular. Thus if we were to define a controller which was defined within the another controller (nested controllers), then the inner controller would inherit the scope of the parent controller. This inheritance would follow JavaScript prototypal inheritance. Let’s say the parent controller defined a variable through $scope.myInt = 6. The child controller would inherit the scope through java prototypical inheritance. This basically means that the child scope has a variable myInt that points to the parent scopes myInt variable. Now if we assigned the value of myInt in the parent, the child scope would be updated with the same value as the child scope’s myInt variable points to the parent scope’s myInt variable. However, if we were to assign the value of the myInt variable in the child scope, then the link of that variable to the parent scope would be broken as the variable myInt in the child scope now points to the value 6 and not to the parent scope’s myInt variable. But, if we defined a variable model in the parent scope, then the child scope will also have a variable model that points to the model variable in the parent scope. Updating the value of $scope.model.myInt in the parent scope would change the model variable in the child scope too as the variable is pointed to the model variable in the parent scope. Now changing the value of $scope.model.myInt in the child scope would ALSO change the value in the parent scope. This is because the model reference in the child scope is pointed to the scope variable in the parent. We did no new assignment to the model variable in the child scope. We only changed an attribute of the model variable. Since the model variable (in the child scope) points to the model variable in the parent scope, we have successfully changed the value of myInt in the parent scope. Thus the value of $scope.model.myInt in the parent scope becomes the “single source of truth“. This is a tricky concept, thus it is considered good practice to NOT use scope inheritance. More info on prototypal inheritance in Angular can be found in the “JavaScript Prototypal Inheritance” section at the following URL: https://github.com/angular/angular.js/wiki/Understanding­Scopes. Building It: An Angular JS application using a .NET Web API Backend Now that we have a perspective on the basic components of an MVVM application built using Angular, let’s build something useful. We will build an application that can be used to send out SMS messages to a given phone number. The following diagram describes the architecture of the application we are going to build: Fig 7: Broad application architecture We are going to add an HTML Partial to our project. This partial will contain the form fields that will accept the phone number and message that needs to be sent as an SMS. It will also display all the messages that have previously been sent. All the executable code that is run on the occurrence of events (button clicks etc.) in the view resides in the controller. The controller interacts with the ASP.NET WebAPI to get a history of SMS messages, add a message etc. through a REST based API. For the purposes of simplicity, we will use an in memory data structure for the purposes of creating this application. Thus, the tasks ahead of us are: Creating the REST WebApi with GET, PUT, POST, DELETE methods. Creating the SmsView.html partial Creating the SmsController controller with methods that are called from the SmsView.html partial Add a new route that loads the controller and the partial. 1. Creating the REST WebAPI This is a simple task that should be quite straightforward to any .NET developer. The following listing shows our ApiController: public class SmsMessage { public string to { get; set; } public string message { get; set; } } public class SmsResource : SmsMessage { public int smsId { get; set; } } public class SmsResourceController : ApiController { public static Dictionary<int, SmsResource> messages = new Dictionary<int, SmsResource>(); public static int currentId = 0; // GET api/<controller> public List<SmsResource> Get() { List<SmsResource> result = new List<SmsResource>(); foreach (int key in messages.Keys) { result.Add(messages[key]); } return result; } // GET api/<controller>/5 public SmsResource Get(int id) { if (messages.ContainsKey(id)) return messages[id]; return null; } // POST api/<controller> public List<SmsResource> Post([FromBody] SmsMessage value) { //Synchronize on messages so we don't have id collisions lock (messages) { SmsResource res = (SmsResource) value; res.smsId = currentId++; messages.Add(res.smsId, res); //SentlyPlusSmsSender.SendMessage(value.to, value.message); return Get(); } } // PUT api/<controller>/5 public List<SmsResource> Put(int id, [FromBody] SmsMessage value) { //Synchronize on messages so we don't have id collisions lock (messages) { if (messages.ContainsKey(id)) { //Update the message messages[id].message = value.message; messages[id].to = value.message; } return Get(); } } // DELETE api/<controller>/5 public List<SmsResource> Delete(int id) { if (messages.ContainsKey(id)) { messages.Remove(id); } return Get(); } } Once this class is defined, we should be able to access the WebAPI by a simple GET request using the browser: http://localhost:port/api/SmsResource Notice the commented line: //SentlyPlusSmsSender.SendMessage The SentlyPlusSmsSender class is defined in the attached solution. We have shown this line as commented as we want to explain the core Angular concepts. If you load the attached solution, this line is uncommented in the source and an actual SMS will be sent! By default, the API returns XML. For consumption of the API in Angular, we would like it to return JSON. To change the default to JSON, we make the following change to WebApiConfig.cs file located in the App_Start folder. public static class WebApiConfig { public static void Register(HttpConfiguration config) { config.Routes.MapHttpRoute( name: "DefaultApi", routeTemplate: "api/{controller}/{id}", defaults: new { id = RouteParameter.Optional } ); var appXmlType = config.Formatters.XmlFormatter. SupportedMediaTypes. FirstOrDefault( t => t.MediaType == "application/xml"); config.Formatters.XmlFormatter.SupportedMediaTypes.Remove(appXmlType); } } We now have our backend REST Api which we can consume from Angular! 2. Creating the SmsView.html partial This simple partial will define two fields: the destination phone number (international format starting with a +) and the message. These fields will be bound to model.phoneNumber and model.message. We will also add a button that we shall hook up to sendMessage() in the controller. A list of all previously sent messages (bound to model.allMessages) will also be displayed below the form input. The following code shows the code for the partial: <!--­­ If model.errorMessage is defined, then render the error div -­­> <div class="alert alert-­danger alert-­dismissable" style="margin­-top: 30px;" ng­-show="model.errorMessage != undefined"> <button type="button" class="close" data­dismiss="alert" aria­hidden="true">&times;</button> <strong>Error!</strong> <br /> {{ model.errorMessage }} </div> <!--­­ The input fields bound to the model --­­> <div class="well" style="margin-­top: 30px;"> <table style="width: 100%;"> <tr> <td style="width: 45%; text-­align: center;"> <input type="text" placeholder="Phone number (eg; +44 7778 609466)" ng­-model="model.phoneNumber" class="form-­control" style="width: 90%" onkeypress="return checkPhoneInput();" /> </td> <td style="width: 45%; text-­align: center;"> <input type="text" placeholder="Message" ng­-model="model.message" class="form-­control" style="width: 90%" /> </td> <td style="text-­align: center;"> <button class="btn btn-­danger" ng-­click="sendMessage();" ng-­disabled="model.isAjaxInProgress" style="margin­right: 5px;">Send</button> <img src="/Content/ajax-­loader.gif" ng­-show="model.isAjaxInProgress" /> </td> </tr> </table> </div> <!--­­ The past messages ­­--> <div style="margin-­top: 30px;"> <!­­-- The following div is shown if there are no past messages --­­> <div ng­-show="model.allMessages.length == 0"> No messages have been sent yet! </div> <!--­­ The following div is shown if there are some past messages --­­> <div ng-­show="model.allMessages.length == 0"> <table style="width: 100%;" class="table table-­striped"> <tr> <td>Phone Number</td> <td>Message</td> <td></td> </tr> <!--­­ The ng-­repeat directive is line the repeater control in .NET, but as you can see this partial is pure HTML which is much cleaner --> <tr ng-­repeat="message in model.allMessages"> <td>{{ message.to }}</td> <td>{{ message.message }}</td> <td> <button class="btn btn-­danger" ng-­click="delete(message.smsId);" ng­-disabled="model.isAjaxInProgress">Delete</button> </td> </tr> </table> </div> </div> The above code is commented and should be self explanatory. Conditional rendering is achieved through using the ng-­show=”condition” attribute on various div tags. Input fields are bound to the model and the send button is bound to the sendMessage() function in the controller as through the ng­click=”sendMessage()” attribute defined on the button tag. While AJAX calls are taking place, the controller sets model.isAjaxInProgress to true. Based on this variable, buttons are disabled through the ng-­disabled directive which is added as an attribute to the buttons. The ng-­repeat directive added as an attribute to the tr tag causes the table row to be rendered multiple times much like an ASP.NET repeater. 3. Creating the SmsController controller The penultimate piece of our application is the controller which responds to events from our view and interacts with our MVC4 REST WebAPI. The following listing shows the code we need to add to /app/js/controllers.js. Note that controller definitions can be chained. Also note that this controller “asks for” the $http service. The $http service is a simple way in Angular to do AJAX. So far we have only encountered modules, controllers, views and directives in Angular. The $http is new entity in Angular called a service. More information on Angular services can be found at the following URL: http://docs.angularjs.org/guide/dev_guide.services.understanding_services. .controller('SmsController', ['$scope', '$http', function ($scope, $http) { //We define the model $scope.model = {}; //We define the allMessages array in the model //that will contain all the messages sent so far $scope.model.allMessages = []; //The error if any $scope.model.errorMessage = undefined; //We initially load data so set the isAjaxInProgress = true; $scope.model.isAjaxInProgress = true; //Load all the messages $http({ url: '/api/smsresource', method: "GET" }). success(function (data, status, headers, config) { this callback will be called asynchronously //when the response is available $scope.model.allMessages = data; //We are done with AJAX loading $scope.model.isAjaxInProgress = false; }). error(function (data, status, headers, config) { //called asynchronously if an error occurs //or server returns response with an error status. $scope.model.errorMessage = "Error occurred status:" + status; //We are done with AJAX loading $scope.model.isAjaxInProgress = false; }); $scope.delete = function (id) { //We are making an ajax call so we set this to true $scope.model.isAjaxInProgress = true; $http({ url: '/api/smsresource/' + id, method: "DELETE" }). success(function (data, status, headers, config) { // this callback will be called asynchronously // when the response is available $scope.model.allMessages = data; //We are done with AJAX loading $scope.model.isAjaxInProgress = false; }); error(function (data, status, headers, config) { // called asynchronously if an error occurs // or server returns response with an error status. $scope.model.errorMessage = "Error occurred status:" + status; //We are done with AJAX loading $scope.model.isAjaxInProgress = false; }); } $scope.sendMessage = function () { $scope.model.errorMessage = undefined; var message = ''; if($scope.model.message != undefined) message = $scope.model.message.trim(); if ($scope.model.phoneNumber == undefined || $scope.model.phoneNumber == '' || $scope.model.phoneNumber.length < 10 || $scope.model.phoneNumber[0] != '+') { $scope.model.errorMessage = "You must enter a valid phone number in international format. Eg: +44 7778 609466"; return; } if (message.length == 0) { $scope.model.errorMessage = "You must specify a message!"; return; } //We are making an ajax call so we set this to true $scope.model.isAjaxInProgress = true; $http({ url: '/api/smsresource', method: "POST", data: { to: $scope.model.phoneNumber, message: $scope.model.message } }). success(function (data, status, headers, config) { // this callback will be called asynchronously // when the response is available $scope.model.allMessages = data; //We are done with AJAX loading $scope.model.isAjaxInProgress = false; }). error(function (data, status, headers, config) { // called asynchronously if an error occurs // or server returns response with an error status. $scope.model.errorMessage = "Error occurred status:" + status // We are done with AJAX loading $scope.model.isAjaxInProgress = false; }); } }]); We can see from the previous listing how the functions that are called from the view are defined in the controller. It should also be evident how easy it is to make AJAX calls to consume our MVC4 REST WebAPI. Now we are left with the final piece. We need to define a route that associates a particular path with the view we have defined and the controller we have defined. 4. Add a new route that loads the controller and the partial This is the easiest part of the puzzle. We simply define another route in the /app/js/app.js file: $routeProvider.when('/sms', { templateUrl: '/app/partials/smsview.html', controller: 'SmsController' }); Conclusion In this article we have seen how much of the server side functionality in the MVC4 framework can be moved to the browser thus delivering a snappy and fast user interface. We have seen how we can build client side HTML only views that avoid the messy syntax offered by server side Razor views. We have built a functioning app from the ground up. The significant advantage of this approach to building web apps is that the front end can be completely platform independent. Even though we used ASP.NET to create our REST API, we could just easily have used any other language such as Node.js, Ruby etc without changing a single line of our front end code. Angular is a rich framework and we have only touched on basic functionality required to create a SPA. For readers who wish to delve further into the Angular framework, we would recommend the following URL as a starting point: http://docs.angularjs.org/misc/started. To get started with the code for this project: Sign up for an account at http://plus.sent.ly (free) Add your phone number Go to the “My Identies Page” Note Down your Sender ID, Consumer Key and Consumer Secret Download the code for this article at: https://docs.google.com/file/d/0BzjEWqSE31yoZjZlV0d0R2Y3eW8/edit?usp=sharing Change the values of Sender Id, Consumer Key and Consumer Secret in the web.config file Run the project through Visual Studio!

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  • strange data annotations issue in MVC 2

    - by femi
    Hello, I came across something strange when creating an edit form with MVC 2. i realised that my error messages come up on form sumission even when i have filled ut valid data! i am using a buddy class which i have configured correctly ( i know that cos i can see my custom errors). Here is the code from the viewmodel that generates this; <%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<TG_Careers.Models.Applicant>" %> <script src="/Scripts/MicrosoftAjax.js" type="text/javascript"></script> <script src="/Scripts/MicrosoftMvcAjax.js" type="text/javascript"></script> <script src="/Scripts/MicrosoftMvcValidation.js" type="text/javascript"></script> <%= Html.ValidationSummary() %> <% Html.EnableClientValidation(); %> <% using (Html.BeginForm()) {%> <div class="confirm-module"> <table cellpadding="4" cellspacing="2"> <tr> <td><%= Html.LabelFor(model => model.FirstName) %> </td> <td><%= Html.EditorFor(model => model.FirstName) %></td> </tr> <tr> <td colspan="2"><%= Html.ValidationMessageFor(model => model.FirstName) %></td> </tr> <tr> <td><%= Html.LabelFor(model => model.MiddleName) %></td> <td><%= Html.EditorFor(model => model.MiddleName) %></td> </tr> <tr> <td colspan="2"><%= Html.ValidationMessageFor(model => model.MiddleName) %></td> </tr> <tr> <td><%= Html.LabelFor(model => model.LastName) %></td> <td><%= Html.EditorFor(model => model.LastName) %></td> </tr> <tr> <td colspan="2"><%= Html.ValidationMessageFor(model => model.LastName) %></td> </tr> <tr> <td><%= Html.LabelFor(model => model.Gender) %></td> <td><%= Html.EditorFor(model => model.Gender) %></td> </tr> <tr> <td colspan="2"><%= Html.ValidationMessageFor(model => model.Gender) %></td> </tr> <tr> <td><%= Html.LabelFor(model => model.MaritalStatus) %></td> <td> <%= Html.EditorFor(model => model.MaritalStatus) %></td> </tr> <tr> <td colspan="2"><%= Html.ValidationMessageFor(model => model.MaritalStatus) %></td> </tr> <tr> <td><%= Html.LabelFor(model => model.DateOfBirth) %></td> <td><%= Html.EditorFor(model => model.DateOfBirth) %></td> </tr> <tr> <td colspan="2"><%= Html.ValidationMessageFor(model => model.DateOfBirth) %></td> </tr> <tr> <td><%= Html.LabelFor(model => model.Address) %></td> <td><%= Html.EditorFor(model => model.Address) %></td> </tr> <tr> <td colspan="2"><%= Html.ValidationMessageFor(model => model.Address) %></td> </tr> <tr> <td><%= Html.LabelFor(model => model.City) %></td> <td><%= Html.EditorFor(model => model.City) %></td> </tr> <tr> <td colspan="2"><%= Html.ValidationMessageFor(model => model.City) %></td> </tr> <tr> <td><%= Html.LabelFor(model => model.State) %></td> <td><%= Html.EditorFor(model => model.State) %></td> </tr> <tr> <td colspan="2"><%= Html.ValidationMessageFor(model => model.State) %></td> </tr> <tr> <td><%= Html.LabelFor(model => model.StateOfOriginID) %></td> <td><%= Html.DropDownList("StateOfOriginID", new SelectList(ViewData["States"] as IEnumerable, "StateID", "Name", Model.StateOfOriginID))%></td> </tr> <tr> <td colspan="2"><%= Html.ValidationMessageFor(model => model.StateOfOriginID) %></td> </tr> <tr> <td><%= Html.LabelFor(model => model.CompletedNYSC) %></td> <td><%= Html.EditorFor(model => model.CompletedNYSC) %></td> </tr> <tr> <td colspan="2"><%= Html.ValidationMessageFor(model => model.CompletedNYSC) %></td> </tr> <tr> <td><%= Html.LabelFor(model => model.YearsOfExperience) %></td> <td><%= Html.EditorFor(model => model.YearsOfExperience) %></td> </tr> <tr> <td colspan="2"><%= Html.ValidationMessageFor(model => model.YearsOfExperience) %></td> </tr> <tr> <td><%= Html.LabelFor(model => model.MobilePhone) %></td> <td><%= Html.EditorFor(model => model.MobilePhone) %></td> </tr> <tr> <td colspan="2"><%= Html.ValidationMessageFor(model => model.MobilePhone) %></td> </tr> <tr> <td><%= Html.LabelFor(model => model.DayPhone) %></td> <td> <%= Html.EditorFor(model => model.DayPhone) %></td> </tr> <tr> <td colspan="2"><%= Html.ValidationMessageFor(model => model.DayPhone) %></td> </tr> <tr> <td><%= Html.LabelFor(model => model.CVFileName) %></td> <td><%= Html.EditorFor(model => model.CVFileName) %></td> </tr> <tr> <td colspan="2"><%= Html.ValidationMessageFor(model => model.CVFileName) %></td> </tr> <tr> <td><%= Html.LabelFor(model => model.CurrentPosition) %></td> <td><%= Html.EditorFor(model => model.CurrentPosition) %></td> </tr> <tr> <td colspan="2"><%= Html.ValidationMessageFor(model => model.CurrentPosition) %></td> </tr> <tr> <td><%= Html.LabelFor(model => model.EmploymentCommenced) %></td> <td><%= Html.EditorFor(model => model.EmploymentCommenced) %></td> </tr> <tr> <td colspan="2"><%= Html.ValidationMessageFor(model => model.EmploymentCommenced) %></td> </tr> <tr> <td><%= Html.LabelFor(model => model.DateofTakingupCurrentPosition) %></td> <td><%= Html.EditorFor(model => model.DateofTakingupCurrentPosition) %></td> </tr> <tr> <td colspan="2"><%= Html.ValidationMessageFor(model => model.DateofTakingupCurrentPosition) %></td> </tr> <tr> <td>&nbsp;</td> <td>&nbsp;</td> </tr> <tr> <td colspan="2">&nbsp;</td> </tr> </table> <p> <input type="submit" value="Save Profile Details" /> </p> </div> <% } %> Any ideas on this one please? Thanks

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  • Entity Framework Update Error in ASP.NET Mvc with related entity

    - by Barry
    I have run into a problem which have searched and tried everything i can to find a solution but to no avail. I am using the same repository and context throughout the process I have a booking entity and a userExtension Entity Below is my image i then get my form collection back from my page and create a new booking public ActionResult Create(FormCollection collection) { Booking toBooking = new Booking(); i then do some validation and property assignment and find an associated BidInstance toBooking.BidInstance = bid; i have checked and the bid is not null. finally i get the user extension file from the Current IPRINCIPAL USER as below UserExtension loggedInUser = m_BookingRepository.GetBookingCurrentUser(User); toBooking.UserExtension = loggedInUser; The Code to do the getUserExtension is : public UserExtension GetBookingCurrentUser(IPrincipal currentUser) { var user = (from u in Context.aspnet_Users .Include("UserExtension") where u.UserName == currentUser.Identity.Name select u).FirstOrDefault(); if (user != null) { var userextension = (from u in Context.UserExtension.Include("aspnet_Users") where u.aspnet_Users.UserId == user.UserId select u).FirstOrDefault(); return userextension; } else{ return null; } } It returns the userextension fine and assigns it fine. i originally used the aspnet_users but encountered this problem so tried to change it to the extension entity. as soon as i call the : Context.AddToBooking(booking); Context.SaveChanges(); i get the following exception and im completely baffled by how to fix it Entities in 'FutureFlyersEntityModel.Booking' participate in the 'FK_Booking_UserExtension' relationship. 0 related 'UserExtension' were found. 1 'UserExtension' is expected. then the final error that comes to the front end is: Metadata information for the relationship 'FutureFlyersModel.FK_Booking_BidInstance' could not be retrieved. Make sure that the EdmRelationshipAttribute for the relationship has been defined in the assembly. Parameter name: relationshipName.. But both the related entities are set in the booking entity passed thruogh PLEASE HELP Im at wits end with this

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  • How do you determine subtype of an entity using Inheritance with Entity Framework 4?

    - by KallDrexx
    I am just starting to use the Entity Framework 4 for the first time ever. So far I am liking it but I am a bit confused on how to correctly do inheritance. I am doing a model-first approach, and I have my Person entity with two subtype entities, Employee and Client. EF is correctly using the table per type approach, however I can't seem to figure out how to determine what type of a Person a specific object is. For example, if I do something like var people = from p in entities.Person select p; return people.ToList<Person>(); In my list that I form from this, all I care about is the Id field so i don't want to actually query all the subtype tables (this is a webpage list with links, so all I need is the name and the Id, all in the Persons table). However, I want to form different lists using this one query, one for each type of person (so one list for Clients and another for Employees). The issue is if I have a Person entity, I can't see any way to determine if that entity is a Client or an Employee without querying the Client or Employee tables directly. How can I easily determine the subtype of an entity without performing a bunch of additional database queries?

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  • How to tell if any entities in context are dirty with .Net Entity Framework 4.0

    - by Mike Gates
    I want to be able to tell if there is any unsaved data in an entity framework context. I have figured out how to use the ObjectStateManager to check the states of existing entities, but there are two issues I have with this. I would prefer a single function to call to see if any entities are unsaved instead of looping though all entities in the context. I can't figure out how to detect entities I have added. This suggests to me that I do not fully understand how the entity context works. For example, if I have the ObjectSet myContext.Employees, and I add a new employee to this set (with .AddObject), I do not see the new entity when I look at the ObjectSet and I also don't see the .Count increase. However, when I do a context.SaveChanges(), my new entity is persisted...huh? I have been unable to find an answer to this in my msdn searches, so I was hoping someone here would be able to clue me in. Thanks in advance.

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  • Using ExecuteQuery() with entity framework, entity class.

    - by sfreelander
    I am trying to jump from ASP Classic to asp.net. I have followed tutorials to get Entity Framework and LINQ to connect to my test database, but I am having difficulties figuring out ExecuteQuery(). I believe the problem is that I need an "entity class" for my database, but I can't figure out how to do it. Here is my simple code: Dim db as New TestModel.TestEntity Dim results AS IEnumerable(OF ???) = db.ExecuteQuery(Of ???)("Select * from Table1") From the microsoft example site, they use an entity class called Customers, but I don't understand what that means.

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  • Dependency injection with n-tier Entity Framework solution

    - by Matthew
    I am currently designing an n-tier solution which is using Entity Framework 5 (.net 4) as its data access strategy, but am concerned about how to incorporate dependency injection to make it testable / flexible. My current solution layout is as follows (my solution is called Alcatraz): Alcatraz.WebUI: An asp.net webform project, the front end user interface, references projects Alcatraz.Business and Alcatraz.Data.Models. Alcatraz.Business: A class library project, contains the business logic, references projects Alcatraz.Data.Access, Alcatraz.Data.Models Alcatraz.Data.Access: A class library project, houses AlcatrazModel.edmx and AlcatrazEntities DbContext, references projects Alcatraz.Data.Models. Alcatraz.Data.Models: A class library project, contains POCOs for the Alcatraz model, no references. My vision for how this solution would work is the web-ui would instantiate a repository within the business library, this repository would have a dependency (through the constructor) of a connection string (not an AlcatrazEntities instance). The web-ui would know the database connection strings, but not that it was an entity framework connection string. In the Business project: public class InmateRepository : IInmateRepository { private string _connectionString; public InmateRepository(string connectionString) { if (connectionString == null) { throw new ArgumentNullException("connectionString"); } EntityConnectionStringBuilder connectionBuilder = new EntityConnectionStringBuilder(); connectionBuilder.Metadata = "res://*/AlcatrazModel.csdl|res://*/AlcatrazModel.ssdl|res://*/AlcatrazModel.msl"; connectionBuilder.Provider = "System.Data.SqlClient"; connectionBuilder.ProviderConnectionString = connectionString; _connectionString = connectionBuilder.ToString(); } public IQueryable<Inmate> GetAllInmates() { AlcatrazEntities ents = new AlcatrazEntities(_connectionString); return ents.Inmates; } } In the Web UI: IInmateRepository inmateRepo = new InmateRepository(@"data source=MATTHEW-PC\SQLEXPRESS;initial catalog=Alcatraz;integrated security=True;"); List<Inmate> deathRowInmates = inmateRepo.GetAllInmates().Where(i => i.OnDeathRow).ToList(); I have a few related questions about this design. 1) Does this design even make sense in terms of Entity Frameworks capabilities? I heard that Entity framework uses the Unit-of-work pattern already, am I just adding another layer of abstract unnecessarily? 2) I don't want my web-ui to directly communicate with Entity Framework (or even reference it for that matter), I want all database access to go through the business layer as in the future I will have multiple projects using the same business layer (web service, windows application, etc.) and I want to have it easy to maintain / update by having the business logic in one central area. Is this an appropriate way to achieve this? 3) Should the Business layer even contain repositories, or should that be contained within the Access layer? If where they are is alright, is passing a connection string a good dependency to assume? Thanks for taking the time to read!

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  • Vote of Disconfidence to Entity Framework

    - by Ricardo Peres
    A friend of mine has found the following problem with Entity Framework 4: Two simple classes and one association between them (one to many): One condition to filter out soft-deleted entities (WHERE Deleted = 0): 100 records in the database; A simple query: 1: var l = ctx.Person.Include("Address").Where(x => (x.Address.Name == "317 Oak Blvd." && x.Address.Number == 926) || (x.Address.Name == "891 White Milton Drive" && x.Address.Number == 497)); Will produce the following SQL: 1: SELECT 2: [Extent1].[Id] AS [Id], 3: [Extent1].[FullName] AS [FullName], 4: [Extent1].[AddressId] AS [AddressId], 5: [Extent202].[Id] AS [Id1], 6: [Extent202].[Name] AS [Name], 7: [Extent202].[Number] AS [Number] 8: FROM [dbo].[Person] AS [Extent1] 9: LEFT OUTER JOIN [dbo].[Address] AS [Extent2] ON ([Extent2].[Deleted] = 0) AND ([Extent1].[AddressId] = [Extent2].[Id]) 10: LEFT OUTER JOIN [dbo].[Address] AS [Extent3] ON ([Extent3].[Deleted] = 0) AND ([Extent1].[AddressId] = [Extent3].[Id]) 11: LEFT OUTER JOIN [dbo].[Address] AS [Extent4] ON ([Extent4].[Deleted] = 0) AND ([Extent1].[AddressId] = [Extent4].[Id]) 12: LEFT OUTER JOIN [dbo].[Address] AS [Extent5] ON ([Extent5].[Deleted] = 0) AND ([Extent1].[AddressId] = [Extent5].[Id]) 13: LEFT OUTER JOIN [dbo].[Address] AS [Extent6] ON ([Extent6].[Deleted] = 0) AND ([Extent1].[AddressId] = [Extent6].[Id]) 14: ... 15: WHERE ((N'317 Oak Blvd.' = [Extent2].[Name]) AND (926 = [Extent3].[Number])) 16: ... And will result in 680 MB of memory being taken! Now, Entity Framework has been historically known for producing less than optimal SQL, but 680 MB for 100 entities?! According to Microsoft, the problem will be addressed in the following version, there is a Connect issue open. There is even a whitepaper, Performance Considerations for Entity Framework 5, which talks about some of the changes and optimizations coming on version 5, but by reading it, I got even more concerned: “Once the cache contains a set number of entries (800), we start a timer that periodically (once-per-minute) sweeps the cache.” Say what?! The next version of Entity Framework will spawn timer threads?! When Code First came along, I thought it was a step in the right direction. Sure, it didn’t include some things that NHibernate did for quite some time – for example, different strategies for Id generation that do not rely on IDENTITY columns, which makes INSERT batching impossible, or support for enumerated types – but I thought these would come with the time. Now, enumerated types have, but so did… timer threads! I’m afraid Entity Framework is becoming a monster.

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  • Hibernate unknown entity (not missing @Entity or import javax.persistence.Entity )

    - by david99world
    I've got a really simple class... import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.Table; @Entity @Table(name = "users") public class User { @Column(name = "firstName") private String firstName; @Column(name = "lastName") private String lastName; @Column(name = "email") private String email; @Id @GeneratedValue(strategy=GenerationType.AUTO) @Column(name = "id") private long id; public String getFirstName() { return firstName; } public void setFirstName(String firstName) { this.firstName = firstName; } public String getLastName() { return lastName; } public void setLastName(String lastName) { this.lastName = lastName; } public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } public long getId() { return id; } public void setId(long id) { this.id = id; } } I call it using... public class Main { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub HibernateUtil.buildSessionFactory(); Session session = HibernateUtil.getSessionFactory().getCurrentSession(); session.beginTransaction(); User u = new User(); u.setEmail("[email protected]"); u.setFirstName("David"); u.setLastName("Gray"); session.save(u); session.getTransaction().commit(); System.out.println("Record committed"); session.close(); } } I keep getting... Exception in thread "main" org.hibernate.MappingException: Unknown entity: org.assessme.com.entity.User at org.hibernate.internal.SessionFactoryImpl.getEntityPersister(SessionFactoryImpl.java:1172) at org.hibernate.internal.SessionImpl.getEntityPersister(SessionImpl.java:1316) at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:117) at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:204) at org.hibernate.event.internal.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:55) at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:189) at org.hibernate.event.internal.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:49) at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:90) at org.hibernate.internal.SessionImpl.fireSave(SessionImpl.java:670) at org.hibernate.internal.SessionImpl.save(SessionImpl.java:662) at org.hibernate.internal.SessionImpl.save(SessionImpl.java:658) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:601) at org.hibernate.context.internal.ThreadLocalSessionContext$TransactionProtectionWrapper.invoke(ThreadLocalSessionContext.java:352) at $Proxy4.save(Unknown Source) at Main.main(Main.java:20) hibernateUtil is... import org.hibernate.SessionFactory; import org.hibernate.cfg.Configuration; import org.hibernate.service.ServiceRegistry; import org.hibernate.service.ServiceRegistryBuilder; public class HibernateUtil { private static SessionFactory sessionFactory; private static ServiceRegistry serviceRegistry; public static SessionFactory buildSessionFactory() { try { // Create the SessionFactory from hibernate.cfg.xml Configuration configuration = new Configuration(); configuration.configure(); serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties()).buildServiceRegistry(); return new Configuration().configure().buildSessionFactory(serviceRegistry); } catch (Throwable ex) { // Make sure you log the exception, as it might be swallowed System.err.println("Initial SessionFactory creation failed." + ex); throw new ExceptionInInitializerError(ex); } } public static SessionFactory getSessionFactory() { sessionFactory = new Configuration().configure().buildSessionFactory(serviceRegistry); return sessionFactory; } } does anyone have any ideas as I've looked at so many duplicates but the resolutions don't appear to work for me. hibernate.cfg.xml shown below... <?xml version='1.0' encoding='utf-8'?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <!-- Database connection settings --> <property name="connection.driver_class">com.mysql.jdbc.Driver</property> <property name="connection.url">jdbc:mysql://localhost/ssme</property> <property name="connection.username">root</property> <property name="connection.password">mypassword</property> <!-- JDBC connection pool (use the built-in) --> <property name="connection.pool_size">1</property> <!-- SQL dialect --> <property name="dialect">org.hibernate.dialect.MySQLDialect</property> <!-- Enable Hibernate's automatic session context management --> <property name="current_session_context_class">thread</property> <!-- Disable the second-level cache --> <property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property> <!-- Echo all executed SQL to stdout --> <property name="show_sql">true</property> <!-- Drop and re-create the database schema on startup --> <property name="hbm2ddl.auto">update</property> </session-factory> </hibernate-configuration>

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  • How do I create a dynamic data transfer object dynamically from ADO.net model

    - by Richard
    I have a pretty simple database with 5 tables, PK's and relationships setup, etc. I also have an ASP.net MVC3 project I'm using to create simple web services to feed JSON/XML to a mobile app using post/get. To access my data I'm using an ADO.net entity model class to handle generation of the entities, etc. Due to issues with serialization/circular references created by the auto-generated relations from ADO.net entity model, I've been forced to create "Data transfer objects" to strip out the relations and data that doesn't need to be transferred. Question 1: is there an easier way to create DTOs using the entity framework itself? IE, specify only the entity properties I want to convert to Jsonresults? I don't wish to use any 3rd party frameworks if I can help it. Question 2: A side question for Entity Framework, say I create an ADO.net entity model in one project within a solution. Because that model relies on the connection to the database specified in project A, can project B somehow use that model with a similar connection? Both projects are in the same solution. Thanks!

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  • ASP.NET MVC Postbacks and HtmlHelper Controls ignoring Model Changes

    - by Rick Strahl
    So here's a binding behavior in ASP.NET MVC that I didn't really get until today: HtmlHelpers controls (like .TextBoxFor() etc.) don't bind to model values on Postback, but rather get their value directly out of the POST buffer from ModelState. Effectively it looks like you can't change the display value of a control via model value updates on a Postback operation. To demonstrate here's an example. I have a small section in a document where I display an editable email address: This is what the form displays on a GET operation and as expected I get the email value displayed in both the textbox and plain value display below, which reflects the value in the mode. I added a plain text value to demonstrate the model value compared to what's rendered in the textbox. The relevant markup is the email address which needs to be manipulated via the model in the Controller code. Here's the Razor markup: <div class="fieldcontainer"> <label> Email: &nbsp; <small>(username and <a href="http://gravatar.com">Gravatar</a> image)</small> </label> <div> @Html.TextBoxFor( mod=> mod.User.Email, new {type="email",@class="inputfield"}) @Model.User.Email </div> </div>   So, I have this form and the user can change their email address. On postback the Post controller code then asks the business layer whether the change is allowed. If it's not I want to reset the email address back to the old value which exists in the database and was previously store. The obvious thing to do would be to modify the model. Here's the Controller logic block that deals with that:// did user change email? if (!string.IsNullOrEmpty(oldEmail) && user.Email != oldEmail) { if (userBus.DoesEmailExist(user.Email)) { userBus.ValidationErrors.Add("New email address exists already. Please…"); user.Email = oldEmail; } else // allow email change but require verification by forcing a login user.IsVerified = false; }… model.user = user; return View(model); The logic is straight forward - if the new email address is not valid because it already exists I don't want to display the new email address the user entered, but rather the old one. To do this I change the value on the model which effectively does this:model.user.Email = oldEmail; return View(model); So when I press the Save button after entering in my new email address ([email protected]) here's what comes back in the rendered view: Notice that the textbox value and the raw displayed model value are different. The TextBox displays the POST value, the raw value displays the actual model value which are different. This means that MVC renders the textbox value from the POST data rather than from the view data when an Http POST is active. Now I don't know about you but this is not the behavior I expected - initially. This behavior effectively means that I cannot modify the contents of the textbox from the Controller code if using HtmlHelpers for binding. Updating the model for display purposes in a POST has in effect - no effect. (Apr. 25, 2012 - edited the post heavily based on comments and more experimentation) What should the behavior be? After getting quite a few comments on this post I quickly realized that the behavior I described above is actually the behavior you'd want in 99% of the binding scenarios. You do want to get the POST values back into your input controls at all times, so that the data displayed on a form for the user matches what they typed. So if an error occurs, the error doesn't mysteriously disappear getting replaced either with a default value or some value that you changed on the model on your own. Makes sense. Still it is a little non-obvious because the way you create the UI elements with MVC, it certainly looks like your are binding to the model value:@Html.TextBoxFor( mod=> mod.User.Email, new {type="email",@class="inputfield",required="required" }) and so unless one understands a little bit about how the model binder works this is easy to trip up. At least it was for me. Even though I'm telling the control which model value to bind to, that model value is only used initially on GET operations. After that ModelState/POST values provide the display value. Workarounds The default behavior should be fine for 99% of binding scenarios. But if you do need fix up values based on your model rather than the default POST values, there are a number of ways that you can work around this. Initially when I ran into this, I couldn't figure out how to set the value using code and so the simplest solution to me was simply to not use the MVC Html Helper for the specific control and explicitly bind the model via HTML markup and @Razor expression: <input type="text" name="User.Email" id="User_Email" value="@Model.User.Email" /> And this produces the right result. This is easy enough to create, but feels a little out of place when using the @Html helpers for everything else. As you can see by the difference in the name and id values, you also are forced to remember the naming conventions that MVC imposes in order for ModelBinding to work properly which is a pain to remember and set manually (name is the same as the property with . syntax, id replaces dots with underlines). Use the ModelState Some of my original confusion came because I didn't understand how the model binder works. The model binder basically maintains ModelState on a postback, which holds a value and binding errors for each of the Post back value submitted on the page that can be mapped to the model. In other words there's one ModelState entry for each bound property of the model. Each ModelState entry contains a value property that holds AttemptedValue and RawValue properties. The AttemptedValue is essentially the POST value retrieved from the form. The RawValue is the value that the model holds. When MVC binds controls like @Html.TextBoxFor() or @Html.TextBox(), it always binds values on a GET operation. On a POST operation however, it'll always used the AttemptedValue to display the control. MVC binds using the ModelState on a POST operation, not the model's value. So, if you want the behavior that I was expecting originally you can actually get it by clearing the ModelState in the controller code:ModelState.Clear(); This clears out all the captured ModelState values, and effectively binds to the model. Note this will produce very similar results - in fact if there are no binding errors you see exactly the same behavior as if binding from ModelState, because the model has been updated from the ModelState already and binding to the updated values most likely produces the same values you would get with POST back values. The big difference though is that any values that couldn't bind - like say putting a string into a numeric field - will now not display back the value the user typed, but the default field value or whatever you changed the model value to. This is the behavior I was actually expecting previously. But - clearing out all values might be a bit heavy handed. You might want to fix up one or two values in a model but rarely would you want the entire model to update from the model. So, you can also clear out individual values on an as needed basis:if (userBus.DoesEmailExist(user.Email)) { userBus.ValidationErrors.Add("New email address exists already. Please…"); user.Email = oldEmail; ModelState.Remove("User.Email"); } This allows you to remove a single value from the ModelState and effectively allows you to replace that value for display from the model. Why? While researching this I came across a post from Microsoft's Brad Wilson who describes the default binding behavior best in a forum post: The reason we use the posted value for editors rather than the model value is that the model may not be able to contain the value that the user typed. Imagine in your "int" editor the user had typed "dog". You want to display an error message which says "dog is not valid", and leave "dog" in the editor field. However, your model is an int: there's no way it can store "dog". So we keep the old value. If you don't want the old values in the editor, clear out the Model State. That's where the old value is stored and pulled from the HTML helpers. There you have it. It's not the most intuitive behavior, but in hindsight this behavior does make some sense even if at first glance it looks like you should be able to update values from the model. The solution of clearing ModelState works and is a reasonable one but you have to know about some of the innards of ModelState and how it actually works to figure that out.© Rick Strahl, West Wind Technologies, 2005-2012Posted in ASP.NET  MVC   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Tips on ensuring Model Quality

    - by [email protected]
    Given enough data that represents well the domain and models that reflect exactly the decision being optimized, models usually provide good predictions that ensure lift. Nevertheless, sometimes the modeling situation is less than ideal. In this blog entry we explore the problems found in a few such situations and how to avoid them.1 - The Model does not reflect the problem you are trying to solveFor example, you may be trying to solve the problem: "What product should I recommend to this customer" but your model learns on the problem: "Given that a customer has acquired our products, what is the likelihood for each product". In this case the model you built may be too far of a proxy for the problem you are really trying to solve. What you could do in this case is try to build a model based on the result from recommendations of products to customers. If there is not enough data from actual recommendations, you could use a hybrid approach in which you would use the [bad] proxy model until the recommendation model converges.2 - Data is not predictive enoughIf the inputs are not correlated with the output then the models may be unable to provide good predictions. For example, if the input is the phase of the moon and the weather and the output is what car did the customer buy, there may be no correlations found. In this case you should see a low quality model.The solution in this case is to include more relevant inputs.3 - Not enough cases seenIf the data learned does not include enough cases, at least 200 positive examples for each output, then the quality of recommendations may be low. The obvious solution is to include more data records. If this is not possible, then it may be possible to build a model based on the characteristics of the output choices rather than the choices themselves. For example, instead of using products as output, use the product category, price and brand name, and then combine these models.4 - Output leaking into input giving the false impression of good quality modelsIf the input data in the training includes values that have changed or are available only because the output happened, then you will find some strong correlations between the input and the output, but these strong correlations do not reflect the data that you will have available at decision (prediction) time. For example, if you are building a model to predict whether a web site visitor will succeed in registering, and the input includes the variable DaysSinceRegistration, and you learn when this variable has already been set, you will probably see a big correlation between having a Zero (or one) in this variable and the fact that registration was successful.The solution is to remove these variables from the input or make sure they reflect the value as of the time of decision and not after the result is known. 

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  • Looking into Enum Support in Entity Framework 5.0 Code First

    - by nikolaosk
    In this post I will show you with a hands-on demo the enum support that is available in Visual Studio 2012, .Net Framework 4.5 and Entity Framework 5.0. You can have a look at this post to learn about the support of multilple diagrams per model that exists in Entity Framework 5.0. We will demonstrate this with a step by step example. I will use Visual Studio 2012 Ultimate. You can also use Visual Studio 2012 Express Edition. Before I move on to the actual demo I must say that in EF 5.0 an enumeration can have the following types. Byte Int16 Int32 Int64 Sbyte Obviously I cannot go into much detail on what EF is and what it does. I will give again a short introduction.The .Net framework provides support for Object Relational Mapping through EF. So EF is a an ORM tool and it is now the main data access technology that microsoft works on. I use it quite extensively in my projects. Through EF we have many things out of the box provided for us. We have the automatic generation of SQL code.It maps relational data to strongly types objects.All the changes made to the objects in the memory are persisted in a transactional way back to the data store. You can find in this post an example on how to use the Entity Framework to retrieve data from an SQL Server Database using the "Database/Schema First" approach. In this approach we make all the changes at the database level and then we update the model with those changes. In this post you can see an example on how to use the "Model First" approach when working with ASP.Net and the Entity Framework. This model was firstly introduced in EF version 4.0 and we could start with a blank model and then create a database from that model.When we made changes to the model , we could recreate the database from the new model. You can search in my blog, because I have posted many posts regarding ASP.Net and EF. I assume you have a working knowledge of C# and know a few things about EF. The Code First approach is the more code-centric than the other two. Basically we write POCO classes and then we persist to a database using something called DBContext. Code First relies on DbContext. We create 2,3 classes (e.g Person,Product) with properties and then these classes interact with the DbContext class. We can create a new database based upon our POCOS classes and have tables generated from those classes.We do not have an .edmx file in this approach.By using this approach we can write much easier unit tests. DbContext is a new context class and is smaller,lightweight wrapper for the main context class which is ObjectContext (Schema First and Model First). Let's begin building our sample application. 1) Launch Visual Studio. Create an ASP.Net Empty Web application. Choose an appropriate name for your application. 2) Add a web form, default.aspx page to the application. 3) Now we need to make sure the Entity Framework is included in our project. Go to Solution Explorer, right-click on the project name.Then select Manage NuGet Packages...In the Manage NuGet Packages dialog, select the Online tab and choose the EntityFramework package.Finally click Install. Have a look at the picture below   4) Create a new folder. Name it CodeFirst . 5) Add a new item in your application, a class file. Name it Footballer.cs. This is going to be a simple POCO class.Place it in the CodeFirst folder. The code follows public class Footballer { public int FootballerID { get; set; } public string FirstName { get; set; } public string LastName { get; set; } public double Weight { get; set; } public double Height { get; set; } public DateTime JoinedTheClub { get; set; } public int Age { get; set; } public List<Training> Trainings { get; set; } public FootballPositions Positions { get; set; } }    Now I am going to define my enum values in the same class file, Footballer.cs    public enum FootballPositions    {        Defender,        Midfielder,        Striker    } 6) Now we need to create the Training class. Add a new class to your application and place it in the CodeFirst folder.The code for the class follows.     public class Training     {         public int TrainingID { get; set; }         public int TrainingDuration { get; set; }         public string TrainingLocation { get; set; }     }   7) Then we need to create a context class that inherits from DbContext.Add a new class to the CodeFirst folder.Name it FootballerDBContext.Now that we have the entity classes created, we must let the model know.I will have to use the DbSet<T> property.The code for this class follows       public class FootballerDBContext:DbContext     {         public DbSet<Footballer> Footballers { get; set; }         public DbSet<Training> Trainings { get; set; }     } Do not forget to add  (using System.Data.Entity;) in the beginning of the class file 8) We must take care of the connection string. It is very easy to create one in the web.config.It does not matter that we do not have a database yet.When we run the DbContext and query against it,it will use a connection string in the web.config and will create the database based on the classes. In my case the connection string inside the web.config, looks like this      <connectionStrings>    <add name="CodeFirstDBContext"  connectionString="server=.\SqlExpress;integrated security=true;"  providerName="System.Data.SqlClient"/>                       </connectionStrings>   9) Now it is time to create Linq to Entities queries to retrieve data from the database . Add a new class to your application in the CodeFirst folder.Name the file DALfootballer.cs We will create a simple public method to retrieve the footballers. The code for the class follows public class DALfootballer     {         FootballerDBContext ctx = new FootballerDBContext();         public List<Footballer> GetFootballers()         {             var query = from player in ctx.Footballers where player.FirstName=="Jamie" select player;             return query.ToList();         }     }   10) Place a GridView control on the Default.aspx page and leave the default name.Add an ObjectDataSource control on the Default.aspx page and leave the default name. Set the DatasourceID property of the GridView control to the ID of the ObjectDataSource control.(DataSourceID="ObjectDataSource1" ). Let's configure the ObjectDataSource control. Click on the smart tag item of the ObjectDataSource control and select Configure Data Source. In the Wizzard that pops up select the DALFootballer class and then in the next step choose the GetFootballers() method.Click Finish to complete the steps of the wizzard. Build your application.  11)  Let's create an Insert method in order to insert data into the tables. I will create an Insert() method and for simplicity reasons I will place it in the Default.aspx.cs file. private void Insert()        {            var footballers = new List<Footballer>            {                new Footballer {                                 FirstName = "Steven",LastName="Gerrard", Height=1.85, Weight=85,Age=32, JoinedTheClub=DateTime.Parse("12/12/1999"),Positions=FootballPositions.Midfielder,                Trainings = new List<Training>                             {                                     new Training {TrainingDuration = 3, TrainingLocation="MelWood"},                    new Training {TrainingDuration = 2, TrainingLocation="Anfield"},                    new Training {TrainingDuration = 2, TrainingLocation="MelWood"},                }                            },                            new Footballer {                                  FirstName = "Jamie",LastName="Garragher", Height=1.89, Weight=89,Age=34, JoinedTheClub=DateTime.Parse("12/02/2000"),Positions=FootballPositions.Defender,                Trainings = new List<Training>                                             {                                 new Training {TrainingDuration = 3, TrainingLocation="MelWood"},                new Training {TrainingDuration = 5, TrainingLocation="Anfield"},                new Training {TrainingDuration = 6, TrainingLocation="Anfield"},                }                           }                    };            footballers.ForEach(foot => ctx.Footballers.Add(foot));            ctx.SaveChanges();        }   12) In the Page_Load() event handling routine I called the Insert() method.        protected void Page_Load(object sender, EventArgs e)        {                   Insert();                }  13) Run your application and you will see that the following result,hopefully. You can see clearly that the data is returned along with the enum value.  14) You must have also a look at the database.Launch SSMS and see the database and its objects (data) created from EF Code First.Have a look at the picture below. Hopefully now you have seen the support that exists in EF 5.0 for enums.Hope it helps !!!

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  • MVVM- Expose Model object in ViewModel

    - by Angel
    I have a wpf MVVM application , I exposed my model object into my viewModel by creating an instance of Model class (which cause dependency) into ViewModel , and instead of creating seperate VM properties , I wrap the Model properties inside my ViewModel Property. My model is just an entity framework generated proxy classes. Here is my Model class : public partial class TblProduct { public TblProduct() { this.TblPurchaseDetails = new HashSet<TblPurchaseDetail>(); this.TblPurchaseOrderDetails = new HashSet<TblPurchaseOrderDetail>(); this.TblSalesInvoiceDetails = new HashSet<TblSalesInvoiceDetail>(); this.TblSalesOrderDetails = new HashSet<TblSalesOrderDetail>(); } public int ProductId { get; set; } public string ProductCode { get; set; } public string ProductName { get; set; } public int CategoryId { get; set; } public string Color { get; set; } public Nullable<decimal> PurchaseRate { get; set; } public Nullable<decimal> SalesRate { get; set; } public string ImagePath { get; set; } public bool IsActive { get; set; } public virtual TblCompany TblCompany { get; set; } public virtual TblProductCategory TblProductCategory { get; set; } public virtual TblUser TblUser { get; set; } public virtual ICollection<TblPurchaseDetail> TblPurchaseDetails { get; set; } public virtual ICollection<TblPurchaseOrderDetail> TblPurchaseOrderDetails { get; set; } public virtual ICollection<TblSalesInvoiceDetail> TblSalesInvoiceDetails { get; set; } public virtual ICollection<TblSalesOrderDetail> TblSalesOrderDetails { get; set; } } Here is my ViewModel , public class ProductViewModel : WorkspaceViewModel { #region Constructor public ProductViewModel() { StartApp(); } #endregion //Constructor #region Properties private IProductDataService _dataService; public IProductDataService DataService { get { if (_dataService == null) { if (IsInDesignMode) { _dataService = new ProductDataServiceMock(); } else { _dataService = new ProductDataService(); } } return _dataService; } } //Get and set Model object private TblProduct _product; public TblProduct Product { get { return _product ?? (_product = new TblProduct()); } set { _product = value; } } #region Public Properties public int ProductId { get { return Product.ProductId; } set { if (Product.ProductId == value) { return; } Product.ProductId = value; RaisePropertyChanged("ProductId"); } } public string ProductName { get { return Product.ProductName; } set { if (Product.ProductName == value) { return; } Product.ProductName = value; RaisePropertyChanged(() => ProductName); } } private ObservableCollection<TblProduct> _productRecords; public ObservableCollection<TblProduct> ProductRecords { get { return _productRecords; } set { _productRecords = value; RaisePropertyChanged("ProductRecords"); } } //Selected Product private TblProduct _selectedProduct; public TblProduct SelectedProduct { get { return _selectedProduct; } set { _selectedProduct = value; if (_selectedProduct != null) { this.ProductId = _selectedProduct.ProductId; this.ProductCode = _selectedProduct.ProductCode; } RaisePropertyChanged("SelectedProduct"); } } #endregion //Public Properties #endregion // Properties #region Commands private ICommand _newCommand; public ICommand NewCommand { get { if (_newCommand == null) { _newCommand = new RelayCommand(() => ResetAll()); } return _newCommand; } } private ICommand _saveCommand; public ICommand SaveCommand { get { if (_saveCommand == null) { _saveCommand = new RelayCommand(() => Save()); } return _saveCommand; } } private ICommand _deleteCommand; public ICommand DeleteCommand { get { if (_deleteCommand == null) { _deleteCommand = new RelayCommand(() => Delete()); } return _deleteCommand; } } #endregion //Commands #region Methods private void StartApp() { LoadProductCollection(); } private void LoadProductCollection() { var q = DataService.GetAllProducts(); this.ProductRecords = new ObservableCollection<TblProduct>(q); } private void Save() { if (SelectedOperateMode == OperateModeEnum.OperateMode.New) { //Pass the Model object into Dataservice for save DataService.SaveProduct(this.Product); } else if (SelectedOperateMode == OperateModeEnum.OperateMode.Edit) { //Pass the Model object into Dataservice for Update DataService.UpdateProduct(this.Product); } ResetAll(); LoadProductCollection(); } #endregion //Methods } Here is my Service class: class ProductDataService:IProductDataService { /// <summary> /// Context object of Entity Framework model /// </summary> private MaizeEntities Context { get; set; } public ProductDataService() { Context = new MaizeEntities(); } public IEnumerable<TblProduct> GetAllProducts() { using(var context=new R_MaizeEntities()) { var q = from p in context.TblProducts where p.IsDel == false select p; return new ObservableCollection<TblProduct>(q); } } public void SaveProduct(TblProduct _product) { using(var context=new R_MaizeEntities()) { _product.LastModUserId = GlobalObjects.LoggedUserID; _product.LastModDttm = DateTime.Now; _product.CompanyId = GlobalObjects.CompanyID; context.TblProducts.Add(_product); context.SaveChanges(); } } public void UpdateProduct(TblProduct _product) { using (var context = new R_MaizeEntities()) { context.TblProducts.Attach(_product); context.Entry(_product).State = EntityState.Modified; _product.LastModUserId = GlobalObjects.LoggedUserID; _product.LastModDttm = DateTime.Now; _product.CompanyId = GlobalObjects.CompanyID; context.SaveChanges(); } } public void DeleteProduct(int _productId) { using (var context = new R_MaizeEntities()) { var product = (from c in context.TblProducts where c.ProductId == _productId select c).First(); product.LastModUserId = GlobalObjects.LoggedUserID; product.LastModDttm = DateTime.Now; product.IsDel = true; context.SaveChanges(); } } } I exposed my model object in my viewModel by creating an instance of it using new keyword, also I instantiated my DataService class in VM, I know this will cause a strong dependency. So , 1- Whats the best way to expose Model object in ViewModel ? 2- Whats the best way to use DataService in VM ?

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  • Reading data from an Entity Framework data model through a WCF Data Service

    - by nikolaosk
    This is going to be the fourth post of a series of posts regarding ASP.Net and the Entity Framework and how we can use Entity Framework to access our datastore. You can find the first one here , the second one here and the third one here . I have a post regarding ASP.Net and EntityDataSource. You can read it here .I have 3 more posts on Profiling Entity Framework applications. You can have a look at them here , here and here . Microsoft with .Net 3.0 Framework, introduced WCF. WCF is Microsoft's...(read more)

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