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  • Entity Framework associations killing performance

    - by Chris
    Here is the performance test i am looking at. I have 8 different entities that are table per type. Some of the entities contain over 100 thousand rows. This particular application does several recursive calculations on the client so I think it may be best to preload the data instead of lazy loading. If there are no associations I can load the entire database in about 3 seconds. As I add associations in any way the performance starts to drastically decline. I am loading all the data the same way (just calling toList() on the entity attached to the context). I ran the test with edmx generated classes and self tracking entities and had similar results. I am sure if I were to try and deal with the associations myself, similar to how I would in a dataset, the performance problem would go away. On the other hand I am pretty sure this is not how the entity framework was intended to being used. Any thoughts or ideas?

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  • Triggers in Entity Framework - Need advice

    - by jaklucky
    Hi all, I am new to Entity Framework and please pardon my ignorance. We have a simple application written using SQL Server and ADO.Net. Now we have got a new requirement that, whenever a particular rows get updated by our application, some business logic has to happen. I have been looking into Triggers in SQL server and it looks like we can do it using triggers. I am also looking at Entity Framework's OnPropertyChange capability. Is it possible to do it with "OnPropertyChange"? I mean, Can I create a model and implement "OnPropertyChange" method? And when our application modifies the rows using ADO.Net, then will it fire "OnPropertyChange" event so that my custome code in "OnPropertyChange" excutes? Thank you in advance for your inputs, Suresh

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  • Dealing with uncertainty in ORM - Entity Framework CodeOnly

    - by Simon Fox
    This is a bit of a strange one but I've just seen something on twitter which kind of baffled me and I'm interested to know more. Rob Conery tweeted the following a couple of hours ago: Class name of the day: "Maybe<T>". Method of the day: "ToMaybe<T>()". He then went on to offer a Tekpub coupon to anyone who could guess where it came from. He linked to a further tweet which had a clue and from that I worked out that it was Entity Framework Code-Only but while trying to determine the usage someone else answered to which Rob replied ...EF CodeOnly - dealing with uncertainty.... So my question boils down to what exactly is he referring to with uncertainty and how does this fit in to Entity Framework Code-Only?

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  • "Dealing with uncertainty" - Entity Framework CodeOnly

    - by Simon Fox
    This is a bit of a strange one but I've just seen something on twitter which kind of baffled me and I'm interested to know more. Rob Conery tweeted the following a couple of hours ago: Class name of the day: "Maybe<T>". Method of the day: "ToMaybe<T>()". He then went on to offer a Tekpub coupon to anyone who could guess where it came from. He linked to a further tweet which had a clue and from that I worked out that it was Entity Framework Code-Only but while trying to determine the usage someone else answered to which Rob replied ...EF CodeOnly - dealing with uncertainty.... So my question boils down to what exactly is he referring to with uncertainty and how does this fit in to Entity Framework Code-Only?

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  • Can Entity Framework be used for the purpose of entity/schema definition at application runtime?

    - by Kabeer
    Hello. Can 'Entity Framework' be used for the purpose of entity definition at application runtime? Ok, to make it simple, here is what I want to achieve: My application is a product. I should be able to define entities at runtime on the basis of inputs gathered from an 'authoring' user (in effect this means 'model first' approach). These entities are of course persistable. Further, after having defined the entities and their relationships, I should be able to make complex queries across them for many reasons, including reports. Is the above possible and how? So far what I have realized is that there is a dependency on Visual Studio.

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  • MVVM- View Model-View Model Communications

    - by user275561
    How do I go about having two view models communicate with one another using MVVM Light. I know how to use the messenger class and register etc.. Here is my Scenario A Settings View ---> a Settings View Model . . . A MainPage View ---> A MainPage ViewModel If something changes in the Settings View it will Message back to the Settings View Model. So then I want the Settings View Model to communicate to the MainPage View Model about what changed. THe MainPage ViewModel will then tell the View.

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  • Using a join model to relate a model to itself

    - by Gabe Hollombe
    I have two models: User MentoringRelationship MentoringRelationship is a join model that has a mentor_id column and a mentee_id column (both of these reference user_ids from the users table). How can I specify a relation called 'mentees' on the User class that will return all of the users mentored by this user, using the MentoringRelationships join table? What relations do we need to declare in the User model and in the MentoringRelationship model?

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  • MVC Entity Model not showing my table

    - by Jessica
    I have a database with multiple tables, and some basic relationships. Here is an example of the problem I am having: My Database: **Org** ID Name etc **Detail1** ID D1name **Org_Detail1** Org_ID Detail1_ID **Detail2** ID D2Name **Org_Detail2** Org_ID Detial1_ID BooleanField My problem is, the Org_detail1 table is not showing up in the entity model, but the Org_Details2 table does. I thought it may have been because the Org_Detail1 table only contains two ID fields that are both primary keys, while the Org_Details2 table contains 2 primary key ID fields as well as a boolean field. If I add a dummy field to Org_detail1 and update it, it still won't show up and wont allow me to add a new entity relating to the Org_Detail1 table. The table won't even show up in the list, but it is listed under the tables. Is there any solution to get this table to appear in my model?

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  • Entity Framework 4.1 (Code First) audit column

    - by Ken Pespisa
    I'm using Entity Framework 4.1 with a Code-First approach on an ASP.NET MVC site Say I have an entity named Profile that keeps track of a user's favorite book, and I want to track when the user updates their favorite book. UPDATED: Using the class below as an example, I want to set the FavoriteBookLastUpdated property to the current date whenever the value of the FavoriteBook property changes. public class Profile { public int Id { get; set; } public string Name { get; set; } public string FavoriteBook { get; set; } public DateTime? FavoriteBookLastUpdated { get; set; } } Right now I just update that field, if appropriate, in the controller's Edit action before calling the DBContext's SaveChanges() method. Is there a way I can put that logic in my model somehow? I'd prefer not to use triggers on the database side.

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  • what is a performance way to 'tree-walking' through my Entity Framework data

    - by Greg
    Hi, I have a Entity Framework design with a few tables that define a "graph". So there can be a large chain of relationships between objects in the few tables via concept of parent/child relationships. What is a performance way to 'tree-walking' through my Entity Framework data? That is I assume I wouldn't want to load the full set of all NODES and RELATIONSHIPS from the database for the purpose of walking the tree, where the end result may only be identifying leaf nodes? Or would this be OK with the way lazy loading may work at the column/parameter level? Else how could I load just the skeleton of the objects and then when needing to refer to any attributes have them lazy load then?

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  • Entity Framework: Setting EntityReference EntityKey causes exception on save

    - by NYSystemsAnalyst
    I have a table with a ModifiedUserID field that is a foreign key to a User table. In entity framework, I'm loading the first table, but not the users table. I have the user ID of the current user, and would like to set the ModifiedUserID to that value for all entities that have been modified prior to saving. Before calling SaveChanges(), I use the ObjectStateManager to get all modified entities. Since I do not have the user object, but I do have the user ID, I set the EntityReference.EntityKey property as follows: entity.UserReference.EntityKey = New EntityKey("MyContainer.User", "UserID", DatabaseUserID) This works fine, but when I execute SaveChanges(), I receive the following error: A relationship is being added or deleted from an AssociationSet 'FK_Table1_User'. With cardinality constraints, a corresponding 'Table1' must also be added or deleted. Now, I see that setting the EntityReference.EntityKey creates a new AssociationSet entry, but how to I prevent this error?

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  • Accessing non-related entities in LinqToSql entity classes

    - by Chris Johnson
    In LinqToSql, if I want to access a non-related entity in an entity partial class, how do I do this without creating a new DataContext? Here's the scenario: I have the tables Client, IssueType and ClientIssueType. A Client may specify a list of IssueTypes if they do not want to use the default IssueTypes. I have the default IssueTypes in the ClientIssueType table with a ClientId of null. In my Client partial I'd like to try to retrieve all IssueTypes, and if none are found, return all default IssueTypes. The only way I can see of accessing the IssueTypes with a null ClientId is by accessing the table through a new DataContext, which is problematic once I want to start assigning them to Issues. Where am I going wrong?

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  • Entity Framework This property descriptor does not support the SetValue

    - by Gayan
    Hello guys, below are my entities which i have created using entity frame work. retailer id name childs(navigation) generated database schema [Id] [int] IDENTITY(1,1) NOT NULL, [Name] nvarchar NOT NULL childern id name RETAILER(navigation) generated database schema [Id] [int] IDENTITY(1,1) NOT NULL, [name] nvarchar NOT NULL [Retailer_Id] [int] NOT NULL, As you can see in the above model the relationship is 1 retailer can have 0 or 1 child. my problem is when i create a new child and set the retailer navigation property of it to a retailer entity it throws the following exception.how do i solve it Error while setting property 'retailer': 'This property descriptor does not support the SetValue method.'.

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  • Entity framework using Data Repository pattern

    - by JamesStuddart
    Hi all, I have been implementing a new project which I have decided to use the repository pattern and Entity Framework. I have sucessfuly implemented basic CRUD methods and I have no moved onto my DeepLoads. From all the examples and documentation I can find to do this I need to call something like this: public Foo DeepLoadFoo() { return (from foobah in Context.Items.Include("bah").Include("foo").Include("foofoo") select foo).Single(); } This doesnt work for me, maybe I am trying to be too lazy but what I would like to achieve would be something along the lines of this: public Foo DeepLoadFoo(Foo entity, Type[] childTypes) { return (from foobah in Context.Items.Include(childTypes).Single(); } Is anything like this possible, or am I stuck with include.include.include.include? Thanks

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  • Navigating by foreign keys in ADO.NET Entity Framework/MySQL

    - by Werg38
    I am using ASP.NET MVC2 on top of a MySQL database in VS2008. I am using the MySQL ADO.NET connector 6.2.3 to provide the connection for the ADO.NET Entity Data Model. This is mostly working ok, however navigating via foreign keys is causing me a real headache! Here is a simplified example.. Car (Table) CarID PK Colour Doors ManufacturerID FK Manufacturer (Table) ManufacturerID PK Name In the edmx file I can see the 1-many relationship shown as a navigation property in the both the Car and Manufacturer tables. I create a Models.CarRepository that allows me to returns a IQueryable. At the View I want to be able to display the Manufacturer.Name for each car. This is not accessible via the object I get returned. What is best way to implement this? Have I encountered a limitation of the Entity Framework/MySQL combination?

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  • In query in Entity Frame work

    - by Syed Salman Raza Zaidi
    I am working on Entity frame work, i have created a method which is returning List of my Table, I am retrieving data on base of grpID(which is foreign key, so i can have multiple records) I have saved these grpID's in an array so I want to run IN command on Entity framework so that i can get records in single List, How can i apply In command,my code is below public List<tblResource> GetResources(long[] grpid) { try { return dataContext.tblResource.Where(c => c.GroupId == grpid && c.IsActive == true).ToList();//This code is not working as i am having array of groupIds } catch (Exception ex) { return ex; } }

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  • Entity Framework .Include() with compile time checking?

    - by Mikey Cee
    Consider the following code, which is calling against an EF generated data context: var context = new DataContext(); var employees = context.Employees.Include("Department"); If I change the name of the entity Department then this code is going to start throwing a runtime error. So I'll have to do some kind of find and replace throughout my code to replace each occurrence of "Department". Is there any way to call the .Include() method in a safe manner, so I get compile time checking for all the entity names being referenced?

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  • What is the correct connection string for SQL 2000 server in entity framework

    - by M-Askman
    I success to use entity framework for MySQL but reverse code can not be used with SQL Server 2000, then i guess to change connection string to connect SQL Server 2000, however, got error <add name="BetterContext" connectionString="Data Source=server2;Initial Catalog=GoodDB;User ID=sa;Password=hello;MultipleActiveResultSets=True;" providerName="System.Data.SqlClient" /> An error occurred while getting provider information from the database. This can be caused by Entity Framework using an incorrect connection string. Check the inner exceptions for details and ensure that the connection string is correct public partial class BetterContext : DbContext { static BetterContext() { Database.SetInitializer<BetterContext>(null); } public livefeedContext() : base("Name=BetterContext") { }

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  • How to handle Foreign Keys with Entity Framework

    - by Jack Marchetti
    I have two entities. Groups. Pools. A Group can create many pools. So I setup my Pool table to have a GroupID foreign key. My code: using (entity _db = new entity()) { Pool p = new Pool(); p.Name = "test"; p.Group.ID = "5"; _db.AddToPool(p); } This doesn't work. I get a null reference exception on p.Group. How do I go about creating a new "Pool" and associating a GroupID?

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  • Entity Framework Security

    - by NYSystemsAnalyst
    In my organization, we are just beginning to use the Entity Framework for some applications. In the past, we have pushed developers to utilize stored procedures for all database access. In addition to helping with SQL injection, we tried to grant logins access to stored procedures only to keep security relatively tight. Although inserting, updating, and deleting are easily done through stored procedures in the EF, it appears to be difficult to use stored procedures to query data with EF. However, using LINQ or Entity SQL and allowing EF to create the queries means giving a user read access to the entire database. How have others handled this dilemma?

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