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  • Hands-on Entity Framework

    People keep saying that Entity Framework is simple to learn. Simple? Well, finally, we're going to be forced to agree, thanks to James Johnson's new series on learning EF the hands-on way.

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  • Should I use dialog boxes in my web application?

    - by Tom
    I'm developing a typical web application with functions like add, remove, view, search and other yada yada. However, I'm uncertain how much I should rely on dialog boxes. Should I have a dialog box for adding information to the system or perhaps only as a confirmation when deleting something? I could also, for example, use a login dialog box instead of a login page. Should modern web sites be designed so that they use dialog boxes? Are there any general guidelines for when to use a dialog box in a web application or is it more "when I feel like it"?

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  • Design pattern for an ASP.NET project using Entity Framework

    - by MPelletier
    I'm building a website in ASP.NET (Web Forms) on top of an engine with business rules (which basically resides in a separate DLL), connected to a database mapped with Entity Framework (in a 3rd, separate project). I designed the Engine first, which has an Entity Framework context, and then went on to work on the website, which presents various reports. I believe I made a terrible design mistake in that the website has its own context (which sounded normal at first). I present this mockup of the engine and a report page's code behind: Engine (in separate DLL): public Engine { DatabaseEntities _engineContext; public Engine() { // Connection string and procedure managed in DB layer _engineContext = DatabaseEntities.Connect(); } public ChangeSomeEntity(SomeEntity someEntity, int newValue) { //Suppose there's some validation too, non trivial stuff SomeEntity.Value = newValue; _engineContext.SaveChanges(); } } And report: public partial class MyReport : Page { Engine _engine; DatabaseEntities _webpageContext; public MyReport() { _engine = new Engine(); _databaseContext = DatabaseEntities.Connect(); } public void ChangeSomeEntityButton_Clicked(object sender, EventArgs e) { SomeEntity someEntity; //Wrong way: //Get the entity from the webpage context someEntity = _webpageContext.SomeEntities.Single(s => s.Id == SomeEntityId); //Send the entity from _webpageContext to the engine _engine.ChangeSomeEntity(someEntity, SomeEntityNewValue); // <- oops, conflict of context //Right(?) way: //Get the entity from the engine context someEntity = _engine.GetSomeEntity(SomeEntityId); //undefined above //Send the entity from the engine's context to the engine _engine.ChangeSomeEntity(someEntity, SomeEntityNewValue); // <- oops, conflict of context } } Because the webpage has its own context, giving the Engine an entity from a different context will cause an error. I happen to know not to do that, to only give the Engine entities from its own context. But this is a very error-prone design. I see the error of my ways now. I just don't know the right path. I'm considering: Creating the connection in the Engine and passing it off to the webpage. Always instantiate an Engine, make its context accessible from a property, sharing it. Possible problems: other conflicts? Slow? Concurrency issues if I want to expand to AJAX? Creating the connection from the webpage and passing it off to the Engine (I believe that's dependency injection?) Only talking through ID's. Creates redundancy, not always practical, sounds archaic. But at the same time, I already recuperate stuff from the page as ID's that I need to fetch anyways. What would be best compromise here for safety, ease-of-use and understanding, stability, and speed?

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  • Entity framework support for table valued functions and thus full text

    - by simonsabin
    One of my most popular posts with over 10, 000 hits is how to enable full text when using LINQ to SQL http://sqlblogcasts.com/blogs/simons/archive/2008/12/18/LINQ-to-SQL---Enabling-Fulltext-searching.aspx , core to this is the use of a table valued function. I’m therefore interested to see that Entity Framework will support table valued functions in the next release for more details have a read of the efdesign blog http://blogs.msdn.com/b/efdesign/archive/2011/01/21/table-valued-function-support...(read more)

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  • Coding a web browser on Windows using a layout engine?

    - by samual johnson
    I've never attempted anything like this before but what I want to do is code a browser for Windows. I know that I can use the web-browser control that Microsoft has released, but I'm interested in seeing how the problem is solved from a lower level. So I want to know what layout engine I should be looking at? Or is a layout engine the best way to go? I've been looking at WebKit, but it seems rather Mac-centric, so I'm wondering if there are any more practical one's for windows? Has Microsoft released the source code for their webbrowser winforms control in the .Net framework? That would be dependent on the CLR anyway, I suppose? Any suggestions?

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  • Web.Config is Cached

    - by SGWellens
    There was a question from a student over on the Asp.Net forums about improving site performance. The concern was that every time an app setting was read from the Web.Config file, the disk would be accessed. With many app settings and many users, it was believed performance would suffer. Their intent was to create a class to hold all the settings, instantiate it and fill it from the Web.Config file on startup. Then, all the settings would be in RAM. I knew this was not correct and didn't want to just say so without any corroboration, so I did some searching. Surprisingly, this is a common misconception. I found other code postings that cached the app settings from Web.Config. Many people even thanked the posters for the code. In a later post, the student said their text book recommended caching the Web.Config file. OK, here's the deal. The Web.Config file is already cached. You do not need to re-cache it. From this article http://msdn.microsoft.com/en-us/library/aa478432.aspx It is important to realize that the entire <appSettings> section is read, parsed, and cached the first time we retrieve a setting value. From that point forward, all requests for setting values come from an in-memory cache, so access is quite fast and doesn't incur any subsequent overhead for accessing the file or parsing the XML. The reason the misconception is prevalent may be because it's hard to search for Web.Config and cache without getting a lot of hits on how to setup caching in the Web.Config file. So here's a string for search engines to index on: "Is the Web.Config file Cached?" A follow up question was, are the connection strings cached? Yes. http://msdn.microsoft.com/en-us/library/ms178683.aspx At run time, ASP.NET uses the Web.Config files to hierarchically compute a unique collection of configuration settings for each incoming URL request. These settings are calculated only once and then cached on the server. And, as everyone should know, if you modify the Web.Config file, the web application will restart. I hope this helps people to NOT write code! Steve WellensCodeProject

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  • Web.Config is Cached

    - by SGWellens
    There was a question from a student over on the Asp.Net forums about improving site performance. The concern was that every time an app setting was read from the Web.Config file, the disk would be accessed. With many app settings and many users, it was believed performance would suffer. Their intent was to create a class to hold all the settings, instantiate it and fill it from the Web.Config file on startup. Then, all the settings would be in RAM. I knew this was not correct and didn't want to just say so without any corroboration, so I did some searching. Surprisingly, this is a common misconception. I found other code postings that cached the app settings from Web.Config. Many people even thanked the posters for the code. In a later post, the student said their text book recommended caching the Web.Config file. OK, here's the deal. The Web.Config file is already cached. You do not need to re-cache it. From this article http://msdn.microsoft.com/en-us/library/aa478432.aspx It is important to realize that the entire <appSettings> section is read, parsed, and cached the first time we retrieve a setting value. From that point forward, all requests for setting values come from an in-memory cache, so access is quite fast and doesn't incur any subsequent overhead for accessing the file or parsing the XML. The reason the misconception is prevalent may be because it's hard to search for Web.Config and cache without getting a lot of hits on how to setup caching in the Web.Config file. So here's a string for search engines to index on: "Is the Web.Config file Cached?" A follow up question was, are the connection strings cached? Yes. http://msdn.microsoft.com/en-us/library/ms178683.aspx At run time, ASP.NET uses the Web.Config files to hierarchically compute a unique collection of configuration settings for each incoming URL request. These settings are calculated only once and then cached on the server. And, as everyone should know, if you modify the Web.Config file, the web application will restart. I hope this helps people to NOT write code!   Steve WellensCodeProject

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  • Using an alternate JSON Serializer in ASP.NET Web API

    - by Rick Strahl
    The new ASP.NET Web API that Microsoft released alongside MVC 4.0 Beta last week is a great framework for building REST and AJAX APIs. I've been working with it for quite a while now and I really like the way it works and the complete set of features it provides 'in the box'. It's about time that Microsoft gets a decent API for building generic HTTP endpoints into the framework. DataContractJsonSerializer sucks As nice as Web API's overall design is one thing still sucks: The built-in JSON Serialization uses the DataContractJsonSerializer which is just too limiting for many scenarios. The biggest issues I have with it are: No support for untyped values (object, dynamic, Anonymous Types) MS AJAX style Date Formatting Ugly serialization formats for types like Dictionaries To me the most serious issue is dealing with serialization of untyped objects. I have number of applications with AJAX front ends that dynamically reformat data from business objects to fit a specific message format that certain UI components require. The most common scenario I have there are IEnumerable query results from a database with fields from the result set rearranged to fit the sometimes unconventional formats required for the UI components (like jqGrid for example). Creating custom types to fit these messages seems like overkill and projections using Linq makes this much easier to code up. Alas DataContractJsonSerializer doesn't support it. Neither does DataContractSerializer for XML output for that matter. What this means is that you can't do stuff like this in Web API out of the box:public object GetAnonymousType() { return new { name = "Rick", company = "West Wind", entered= DateTime.Now }; } Basically anything that doesn't have an explicit type DataContractJsonSerializer will not let you return. FWIW, the same is true for XmlSerializer which also doesn't work with non-typed values for serialization. The example above is obviously contrived with a hardcoded object graph, but it's not uncommon to get dynamic values returned from queries that have anonymous types for their result projections. Apparently there's a good possibility that Microsoft will ship Json.NET as part of Web API RTM release.  Scott Hanselman confirmed this as a footnote in his JSON Dates post a few days ago. I've heard several other people from Microsoft confirm that Json.NET will be included and be the default JSON serializer, but no details yet in what capacity it will show up. Let's hope it ends up as the default in the box. Meanwhile this post will show you how you can use it today with the beta and get JSON that matches what you should see in the RTM version. What about JsonValue? To be fair Web API DOES include a new JsonValue/JsonObject/JsonArray type that allow you to address some of these scenarios. JsonValue is a new type in the System.Json assembly that can be used to build up an object graph based on a dictionary. It's actually a really cool implementation of a dynamic type that allows you to create an object graph and spit it out to JSON without having to create .NET type first. JsonValue can also receive a JSON string and parse it without having to actually load it into a .NET type (which is something that's been missing in the core framework). This is really useful if you get a JSON result from an arbitrary service and you don't want to explicitly create a mapping type for the data returned. For serialization you can create an object structure on the fly and pass it back as part of an Web API action method like this:public JsonValue GetJsonValue() { dynamic json = new JsonObject(); json.name = "Rick"; json.company = "West Wind"; json.entered = DateTime.Now; dynamic address = new JsonObject(); address.street = "32 Kaiea"; address.zip = "96779"; json.address = address; dynamic phones = new JsonArray(); json.phoneNumbers = phones; dynamic phone = new JsonObject(); phone.type = "Home"; phone.number = "808 123-1233"; phones.Add(phone); phone = new JsonObject(); phone.type = "Home"; phone.number = "808 123-1233"; phones.Add(phone); //var jsonString = json.ToString(); return json; } which produces the following output (formatted here for easier reading):{ name: "rick", company: "West Wind", entered: "2012-03-08T15:33:19.673-10:00", address: { street: "32 Kaiea", zip: "96779" }, phoneNumbers: [ { type: "Home", number: "808 123-1233" }, { type: "Mobile", number: "808 123-1234" }] } If you need to build a simple JSON type on the fly these types work great. But if you have an existing type - or worse a query result/list that's already formatted JsonValue et al. become a pain to work with. As far as I can see there's no way to just throw an object instance at JsonValue and have it convert into JsonValue dictionary. It's a manual process. Using alternate Serializers in Web API So, currently the default serializer in WebAPI is DataContractJsonSeriaizer and I don't like it. You may not either, but luckily you can swap the serializer fairly easily. If you'd rather use the JavaScriptSerializer built into System.Web.Extensions or Json.NET today, it's not too difficult to create a custom MediaTypeFormatter that uses these serializers and can replace or partially replace the native serializer. Here's a MediaTypeFormatter implementation using the ASP.NET JavaScriptSerializer:using System; using System.Net.Http.Formatting; using System.Threading.Tasks; using System.Web.Script.Serialization; using System.Json; using System.IO; namespace Westwind.Web.WebApi { public class JavaScriptSerializerFormatter : MediaTypeFormatter { public JavaScriptSerializerFormatter() { SupportedMediaTypes.Add(new System.Net.Http.Headers.MediaTypeHeaderValue("application/json")); } protected override bool CanWriteType(Type type) { // don't serialize JsonValue structure use default for that if (type == typeof(JsonValue) || type == typeof(JsonObject) || type== typeof(JsonArray) ) return false; return true; } protected override bool CanReadType(Type type) { if (type == typeof(IKeyValueModel)) return false; return true; } protected override System.Threading.Tasks.Taskobject OnReadFromStreamAsync(Type type, System.IO.Stream stream, System.Net.Http.Headers.HttpContentHeaders contentHeaders, FormatterContext formatterContext) { var task = Taskobject.Factory.StartNew(() = { var ser = new JavaScriptSerializer(); string json; using (var sr = new StreamReader(stream)) { json = sr.ReadToEnd(); sr.Close(); } object val = ser.Deserialize(json,type); return val; }); return task; } protected override System.Threading.Tasks.Task OnWriteToStreamAsync(Type type, object value, System.IO.Stream stream, System.Net.Http.Headers.HttpContentHeaders contentHeaders, FormatterContext formatterContext, System.Net.TransportContext transportContext) { var task = Task.Factory.StartNew( () = { var ser = new JavaScriptSerializer(); var json = ser.Serialize(value); byte[] buf = System.Text.Encoding.Default.GetBytes(json); stream.Write(buf,0,buf.Length); stream.Flush(); }); return task; } } } Formatter implementation is pretty simple: You override 4 methods to tell which types you can handle and then handle the input or output streams to create/parse the JSON data. Note that when creating output you want to take care to still allow JsonValue/JsonObject/JsonArray types to be handled by the default serializer so those objects serialize properly - if you let either JavaScriptSerializer or JSON.NET handle them they'd try to render the dictionaries which is very undesirable. If you'd rather use Json.NET here's the JSON.NET version of the formatter:// this code requires a reference to JSON.NET in your project #if true using System; using System.Net.Http.Formatting; using System.Threading.Tasks; using System.Web.Script.Serialization; using System.Json; using Newtonsoft.Json; using System.IO; using Newtonsoft.Json.Converters; namespace Westwind.Web.WebApi { public class JsonNetFormatter : MediaTypeFormatter { public JsonNetFormatter() { SupportedMediaTypes.Add(new System.Net.Http.Headers.MediaTypeHeaderValue("application/json")); } protected override bool CanWriteType(Type type) { // don't serialize JsonValue structure use default for that if (type == typeof(JsonValue) || type == typeof(JsonObject) || type == typeof(JsonArray)) return false; return true; } protected override bool CanReadType(Type type) { if (type == typeof(IKeyValueModel)) return false; return true; } protected override System.Threading.Tasks.Taskobject OnReadFromStreamAsync(Type type, System.IO.Stream stream, System.Net.Http.Headers.HttpContentHeaders contentHeaders, FormatterContext formatterContext) { var task = Taskobject.Factory.StartNew(() = { var settings = new JsonSerializerSettings() { NullValueHandling = NullValueHandling.Ignore, }; var sr = new StreamReader(stream); var jreader = new JsonTextReader(sr); var ser = new JsonSerializer(); ser.Converters.Add(new IsoDateTimeConverter()); object val = ser.Deserialize(jreader, type); return val; }); return task; } protected override System.Threading.Tasks.Task OnWriteToStreamAsync(Type type, object value, System.IO.Stream stream, System.Net.Http.Headers.HttpContentHeaders contentHeaders, FormatterContext formatterContext, System.Net.TransportContext transportContext) { var task = Task.Factory.StartNew( () = { var settings = new JsonSerializerSettings() { NullValueHandling = NullValueHandling.Ignore, }; string json = JsonConvert.SerializeObject(value, Formatting.Indented, new JsonConverter[1] { new IsoDateTimeConverter() } ); byte[] buf = System.Text.Encoding.Default.GetBytes(json); stream.Write(buf,0,buf.Length); stream.Flush(); }); return task; } } } #endif   One advantage of the Json.NET serializer is that you can specify a few options on how things are formatted and handled. You get null value handling and you can plug in the IsoDateTimeConverter which is nice to product proper ISO dates that I would expect any Json serializer to output these days. Hooking up the Formatters Once you've created the custom formatters you need to enable them for your Web API application. To do this use the GlobalConfiguration.Configuration object and add the formatter to the Formatters collection. Here's what this looks like hooked up from Application_Start in a Web project:protected void Application_Start(object sender, EventArgs e) { // Action based routing (used for RPC calls) RouteTable.Routes.MapHttpRoute( name: "StockApi", routeTemplate: "stocks/{action}/{symbol}", defaults: new { symbol = RouteParameter.Optional, controller = "StockApi" } ); // WebApi Configuration to hook up formatters and message handlers // optional RegisterApis(GlobalConfiguration.Configuration); } public static void RegisterApis(HttpConfiguration config) { // Add JavaScriptSerializer formatter instead - add at top to make default //config.Formatters.Insert(0, new JavaScriptSerializerFormatter()); // Add Json.net formatter - add at the top so it fires first! // This leaves the old one in place so JsonValue/JsonObject/JsonArray still are handled config.Formatters.Insert(0, new JsonNetFormatter()); } One thing to remember here is the GlobalConfiguration object which is Web API's static configuration instance. I think this thing is seriously misnamed given that GlobalConfiguration could stand for anything and so is hard to discover if you don't know what you're looking for. How about WebApiConfiguration or something more descriptive? Anyway, once you know what it is you can use the Formatters collection to insert your custom formatter. Note that I insert my formatter at the top of the list so it takes precedence over the default formatter. I also am not removing the old formatter because I still want JsonValue/JsonObject/JsonArray to be handled by the default serialization mechanism. Since they process in sequence and I exclude processing for these types JsonValue et al. still get properly serialized/deserialized. Summary Currently DataContractJsonSerializer in Web API is a pain, but at least we have the ability with relatively limited effort to replace the MediaTypeFormatter and plug in our own JSON serializer. This is useful for many scenarios - if you have existing client applications that used MVC JsonResult or ASP.NET AJAX results from ASMX AJAX services you can plug in the JavaScript serializer and get exactly the same serializer you used in the past so your results will be the same and don't potentially break clients. JSON serializers do vary a bit in how they serialize some of the more complex types (like Dictionaries and dates for example) and so if you're migrating it might be helpful to ensure your client code doesn't break when you switch to ASP.NET Web API. Going forward it looks like Microsoft is planning on plugging in Json.Net into Web API and make that the default. I think that's an awesome choice since Json.net has been around forever, is fast and easy to use and provides a ton of functionality as part of this great library. I just wish Microsoft would have figured this out sooner instead of now at the last minute integrating with it especially given that Json.Net has a similar set of lower level JSON objects JsonValue/JsonObject etc. which now will end up being duplicated by the native System.Json stuff. It's not like we don't already have enough confusion regarding which JSON serializer to use (JavaScriptSerializer, DataContractJsonSerializer, JsonValue/JsonObject/JsonArray and now Json.net). For years I've been using my own JSON serializer because the built in choices are both limited. However, with an official encorsement of Json.Net I'm happily moving on to use that in my applications. Let's see and hope Microsoft gets this right before ASP.NET Web API goes gold.© Rick Strahl, West Wind Technologies, 2005-2012Posted in Web Api  AJAX  ASP.NET   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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  • How do you manage large web farms?

    - by Andrew Katz
    I have a quickly growing web farm running IIS 7 (30+ servers). All servers are identical copies of each other and all servers are physical. We update the software about once a month, and in the current process, we follow the following steps: Disable server from pool on F5 load balancer. Disable HTTP Keep-alives in IIS so connections drop quickly. Change default directory of website to new folder containing new binaries. Test server Enable HTTP Keep-alives. Enable server in F5 pool. Move to server 2 Microsoft used to have Application Center which was abandoned a while ago. They have made a second attempt with the Web Farm Framework, but this adds as much QA time testing the release package as it saves in the deployment. Has anyone seen a commercial off the shelf application that is tailored for managing and deploying to large web farms? Thanks!

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  • What Technology can Render Medium Scale 3d Environments in a Web-Browser

    - by JakeM
    I intend to make a web application that displays 3d environments that can be navigated by dragging(with a finger or mouse depending on the platform). The web app will render 3d environments of development sites including contours, water pipeline locations, buildings etc. I am trying to decide what technology/libraries to use that will create a web-app that will work on Android-Web-Browser, iOS-Safari, IE9, Safari, Firefox and Chrome. And also what technology will provide speed in development. I understand that this is 'asking for my cake and eating it too'/'asking for the moon' but I don't know all the technologies out there - so there may be advanced libraries that can render 3d environments across many web-browsers including the main smart phone ones and I dont know of them. The 3d rendering would not be highly detailed buildings or water with effects, but rather simple 3d representations of these objects. The environment would be navigable by dragging around and you could view the landscape in layers(view only contour lines, view only underground pipelines, view only sewerage pipes, etc.). Are there any 3d libraries for web-browsers out there? Is there a way to run OpenGL(or OpenGL ES) through a webbrowser? What technology would you use if you were making this kind of app/web app that should work on desktop Windows, Android, iOS and WindowsPhone? Is there any technology I have failed to mention that would be good for this kind of project? I am tending towards a Browser Driven Web App because I get that cross platform ability(where it even works on linux and MacOS by using compatible web-browsers). Also I know of CSS3 transforms that can create cubes that can rotate in 3d space(NOTE only works for WebKit browsers - so no IE :( ). But I don't know if CSS3 is robust enough to render whole 3d environments? Do you think it could? Maybe I could use HTML5 canvas's for this? Can Google maps create custom 3d maps?

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  • Modular Web App Network Architecture

    - by nairware
    Assuming that I am dealing with dedicated physical servers or VPSs, is it conceivable and does it make sense to have distinct servers setup with the following roles to host a web application? Reverse Proxy Web server Application server Database server Specific points of interest: I am confused how to even separate the web and application servers. My understanding was that such 3-tier architectures were feasible. It is unclear to me if the app server would reside directly between the web and database server, or if the web server could directly interact with the database as well. The app server could either do the computational heavy-lifting on behalf of the app server or it could do heavy-lifting plus control all of the business logic (as implied in the diagram above, thus denying the web server of direct database access). I am also unsure what role the reverse proxy (ex. nginx) could and should fulfill as a web server, given the above mentioned setup. I know that nginx has web server features. But I do not know if it makes sense to have the reverse proxy be its own VPS, given that the web server–in theory–would be separate from the app server.

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  • Entity Framework 4 mapping fragment error when adding new entity scalar

    - by Jason Morse
    I have an Entity Framework 4 model-first design. I create a first draft of my model in the designer and all was well. I compiled, generated database, etc. Later on I tried to add a string scalar (Nullable = true) to one of my existing entities and I keep getting this type of error when I compile: Error 3004: Problem in mapping fragments starting at line 569: No mapping specified for properties MyEntity.MyValue in Set MyEntities. An Entity with Key (PK) will not round-trip when: Entity is type [MyEntities.MyEntity] I keep having to manually open the EDMX file and correct the XML whenever I add scalars. Ideas on what's going on?

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  • Entity Framework 4 ste delete foreign key relationship

    - by user169867
    I'm using EF4 and STE w/ Silverlight. I'm having trouble deleting child records from my primary entity. For some reason I can remove child entities if their foreign key to my primary entity is part of their Primary Key. But if it's not, they don't get removed. I believe these posts explains it: http://mocella.blogspot.com/2010/01/entity-framework-v4-object-graph.html http://blogs.msdn.com/dsimmons/archive/2010/01/31/deleting-foreign-key-relationships-in-ef4.aspx My question is how how do I remove a child record who's foreign key is not part of its primary key in Silverlight where I don't have access to a DeleteObject() function?

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  • Unique Keys not recognized by Entity Framework

    - by David Pfeffer
    I have two tables, Reports and Visualizations. Reports has a field, VisualizationID, which points to Visualization's field of the same name via a foreign key. It also has a unique key declared on the field. VisualizationID is not nullable. This means the relationship has to be 0..1 to 1, because every Reports record must have a unique, not null Visualizations record associated with it. The Entity Framework doesn't see it this way. I'm getting the following error: Error 113: Multiplicity is not valid in Role 'Report' in relationship 'FK_Reports_Visualizations'. Because the Dependent Role properties are not the key properties, the upper bound of the multiplicity of the Dependent Role must be *. What's the problem here? How can I make the EF recognize the proper relationship multiplicity?

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  • Configurable UI Plugin frameworks for .NET Compact Framework

    - by Andy White
    Is anyone aware of any frameworks for configuring UIs and possibly plugins for .NET Compact Framework (rich client) applications? Ideally, I'm hoping to find something that would allow you to bascially configure an application's UI and screenflow via an XML file, or some other configuration mechanism, and allow you to plugin different "Action" classes to take care of specific events, etc. in the app. We basically want to have a base application, which allows you to plugin specific/custom functionality to support different customers. I know it's a lot to find, but feel free to throw out any frameworks that might support any or all of these types of things.

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  • generate only objectLayer of Entity Framework Model by edmgen tool

    - by loviji
    How to generate only objectLayer by edmgen tool, without generating csdl, ssdl and views ? *"%windir%\Microsoft.NET\Framework\v4.0.30319\edmgen.exe" /mode:fullgeneration /c:"Data Source=.\sqlexpress; Initial Catalog=uqs; Integrated Security=SSPI" /project:generateEntityModel /entitycontainer:uqsEntities /namespace:uqsModel /language:CSharp /outobjectlayer:"D:/uqsObjectLayer.cs" * in this script I don't write location to write csdl, ssdl and views , but they are generated in C:\Users\adminUser in windows Vista and objectLayer generated to D:/uqsObjectLayer.cs. If I use /mode:EntityClassGeneration, this option requires the /incsdl argument and either the /project argument or the /outobjectlayer argument. The /language argument is optional. But I don't want use csdl file. As I understand, edmgen.tool can not create objectlayer without csdl file. Now is there alternate way or tool for generating objectlayer from db?

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  • mini cms library/framework?

    - by rap-uvic
    Hello all, I have a web application which needs to allow admins to create content pages. I'd rather not re-invent the wheel here. What I need is something like Joomla, but it doesn't have to be a full fledged CMS. I need a framework or a library that I can use with my current web application which will present a nice interface for admin to create sections/pages, and then edit and style them just like joomla. My web application is built on .Net 3.5 and Sql Server 2005. Any ideas?

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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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  • delete data using entity framework

    - by user3474542
    The objective of the method below is to delete the data from the database using entity framework. I am populating the subscriptions entity by passing two parameters and then calling the atttach and remove method of the context class. Bureau entities is the context class. using (BUREAUEntities bureauEntities = new BUREAUEntities()) { var subscription = new SubcriptionRepository().GetSusbcriptionBySubscriptionTypeId(subscriptionTypeId, companyId); bureauEntities.Subscriptions.Attach((DataAccessLayer.DatabaseModel.Subscription)subscription); bureauEntities.Subscriptions.Remove(subscription); bureauEntities.SaveChanges(); } I am getting the following error message at An entity object cannot be referenced by multiple instances of IEntityChangeTracker at line bureauEntities.Subscriptions.Attach((DataAccessLayer.DatabaseModel.Subscription)subscription); Could somebody tell me where am I going wrong ?

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  • Inheritance Mapping Strategies with Entity Framework Code First CTP5 Part 1: Table per Hierarchy (TPH)

    - by mortezam
    A simple strategy for mapping classes to database tables might be “one table for every entity persistent class.” This approach sounds simple enough and, indeed, works well until we encounter inheritance. Inheritance is such a visible structural mismatch between the object-oriented and relational worlds because object-oriented systems model both “is a” and “has a” relationships. SQL-based models provide only "has a" relationships between entities; SQL database management systems don’t support type inheritance—and even when it’s available, it’s usually proprietary or incomplete. There are three different approaches to representing an inheritance hierarchy: Table per Hierarchy (TPH): Enable polymorphism by denormalizing the SQL schema, and utilize a type discriminator column that holds type information. Table per Type (TPT): Represent "is a" (inheritance) relationships as "has a" (foreign key) relationships. Table per Concrete class (TPC): Discard polymorphism and inheritance relationships completely from the SQL schema.I will explain each of these strategies in a series of posts and this one is dedicated to TPH. In this series we'll deeply dig into each of these strategies and will learn about "why" to choose them as well as "how" to implement them. Hopefully it will give you a better idea about which strategy to choose in a particular scenario. Inheritance Mapping with Entity Framework Code FirstAll of the inheritance mapping strategies that we discuss in this series will be implemented by EF Code First CTP5. The CTP5 build of the new EF Code First library has been released by ADO.NET team earlier this month. EF Code-First enables a pretty powerful code-centric development workflow for working with data. I’m a big fan of the EF Code First approach, and I’m pretty excited about a lot of productivity and power that it brings. When it comes to inheritance mapping, not only Code First fully supports all the strategies but also gives you ultimate flexibility to work with domain models that involves inheritance. The fluent API for inheritance mapping in CTP5 has been improved a lot and now it's more intuitive and concise in compare to CTP4. A Note For Those Who Follow Other Entity Framework ApproachesIf you are following EF's "Database First" or "Model First" approaches, I still recommend to read this series since although the implementation is Code First specific but the explanations around each of the strategies is perfectly applied to all approaches be it Code First or others. A Note For Those Who are New to Entity Framework and Code-FirstIf you choose to learn EF you've chosen well. If you choose to learn EF with Code First you've done even better. To get started, you can find a great walkthrough by Scott Guthrie here and another one by ADO.NET team here. In this post, I assume you already setup your machine to do Code First development and also that you are familiar with Code First fundamentals and basic concepts. You might also want to check out my other posts on EF Code First like Complex Types and Shared Primary Key Associations. A Top Down Development ScenarioThese posts take a top-down approach; it assumes that you’re starting with a domain model and trying to derive a new SQL schema. Therefore, we start with an existing domain model, implement it in C# and then let Code First create the database schema for us. However, the mapping strategies described are just as relevant if you’re working bottom up, starting with existing database tables. I’ll show some tricks along the way that help you dealing with nonperfect table layouts. Let’s start with the mapping of entity inheritance. -- The Domain ModelIn our domain model, we have a BillingDetail base class which is abstract (note the italic font on the UML class diagram below). We do allow various billing types and represent them as subclasses of BillingDetail class. As for now, we support CreditCard and BankAccount: Implement the Object Model with Code First As always, we start with the POCO classes. Note that in our DbContext, I only define one DbSet for the base class which is BillingDetail. Code First will find the other classes in the hierarchy based on Reachability Convention. public abstract class BillingDetail  {     public int BillingDetailId { get; set; }     public string Owner { get; set; }             public string Number { get; set; } } public class BankAccount : BillingDetail {     public string BankName { get; set; }     public string Swift { get; set; } } public class CreditCard : BillingDetail {     public int CardType { get; set; }                     public string ExpiryMonth { get; set; }     public string ExpiryYear { get; set; } } public class InheritanceMappingContext : DbContext {     public DbSet<BillingDetail> BillingDetails { get; set; } } This object model is all that is needed to enable inheritance with Code First. If you put this in your application you would be able to immediately start working with the database and do CRUD operations. Before going into details about how EF Code First maps this object model to the database, we need to learn about one of the core concepts of inheritance mapping: polymorphic and non-polymorphic queries. Polymorphic Queries LINQ to Entities and EntitySQL, as object-oriented query languages, both support polymorphic queries—that is, queries for instances of a class and all instances of its subclasses, respectively. For example, consider the following query: IQueryable<BillingDetail> linqQuery = from b in context.BillingDetails select b; List<BillingDetail> billingDetails = linqQuery.ToList(); Or the same query in EntitySQL: string eSqlQuery = @"SELECT VAlUE b FROM BillingDetails AS b"; ObjectQuery<BillingDetail> objectQuery = ((IObjectContextAdapter)context).ObjectContext                                                                          .CreateQuery<BillingDetail>(eSqlQuery); List<BillingDetail> billingDetails = objectQuery.ToList(); linqQuery and eSqlQuery are both polymorphic and return a list of objects of the type BillingDetail, which is an abstract class but the actual concrete objects in the list are of the subtypes of BillingDetail: CreditCard and BankAccount. Non-polymorphic QueriesAll LINQ to Entities and EntitySQL queries are polymorphic which return not only instances of the specific entity class to which it refers, but all subclasses of that class as well. On the other hand, Non-polymorphic queries are queries whose polymorphism is restricted and only returns instances of a particular subclass. In LINQ to Entities, this can be specified by using OfType<T>() Method. For example, the following query returns only instances of BankAccount: IQueryable<BankAccount> query = from b in context.BillingDetails.OfType<BankAccount>() select b; EntitySQL has OFTYPE operator that does the same thing: string eSqlQuery = @"SELECT VAlUE b FROM OFTYPE(BillingDetails, Model.BankAccount) AS b"; In fact, the above query with OFTYPE operator is a short form of the following query expression that uses TREAT and IS OF operators: string eSqlQuery = @"SELECT VAlUE TREAT(b as Model.BankAccount)                       FROM BillingDetails AS b                       WHERE b IS OF(Model.BankAccount)"; (Note that in the above query, Model.BankAccount is the fully qualified name for BankAccount class. You need to change "Model" with your own namespace name.) Table per Class Hierarchy (TPH)An entire class hierarchy can be mapped to a single table. This table includes columns for all properties of all classes in the hierarchy. The concrete subclass represented by a particular row is identified by the value of a type discriminator column. You don’t have to do anything special in Code First to enable TPH. It's the default inheritance mapping strategy: This mapping strategy is a winner in terms of both performance and simplicity. It’s the best-performing way to represent polymorphism—both polymorphic and nonpolymorphic queries perform well—and it’s even easy to implement by hand. Ad-hoc reporting is possible without complex joins or unions. Schema evolution is straightforward. Discriminator Column As you can see in the DB schema above, Code First has to add a special column to distinguish between persistent classes: the discriminator. This isn’t a property of the persistent class in our object model; it’s used internally by EF Code First. By default, the column name is "Discriminator", and its type is string. The values defaults to the persistent class names —in this case, “BankAccount” or “CreditCard”. EF Code First automatically sets and retrieves the discriminator values. TPH Requires Properties in SubClasses to be Nullable in the Database TPH has one major problem: Columns for properties declared by subclasses will be nullable in the database. For example, Code First created an (INT, NULL) column to map CardType property in CreditCard class. However, in a typical mapping scenario, Code First always creates an (INT, NOT NULL) column in the database for an int property in persistent class. But in this case, since BankAccount instance won’t have a CardType property, the CardType field must be NULL for that row so Code First creates an (INT, NULL) instead. If your subclasses each define several non-nullable properties, the loss of NOT NULL constraints may be a serious problem from the point of view of data integrity. TPH Violates the Third Normal FormAnother important issue is normalization. We’ve created functional dependencies between nonkey columns, violating the third normal form. Basically, the value of Discriminator column determines the corresponding values of the columns that belong to the subclasses (e.g. BankName) but Discriminator is not part of the primary key for the table. As always, denormalization for performance can be misleading, because it sacrifices long-term stability, maintainability, and the integrity of data for immediate gains that may be also achieved by proper optimization of the SQL execution plans (in other words, ask your DBA). Generated SQL QueryLet's take a look at the SQL statements that EF Code First sends to the database when we write queries in LINQ to Entities or EntitySQL. For example, the polymorphic query for BillingDetails that you saw, generates the following SQL statement: SELECT  [Extent1].[Discriminator] AS [Discriminator],  [Extent1].[BillingDetailId] AS [BillingDetailId],  [Extent1].[Owner] AS [Owner],  [Extent1].[Number] AS [Number],  [Extent1].[BankName] AS [BankName],  [Extent1].[Swift] AS [Swift],  [Extent1].[CardType] AS [CardType],  [Extent1].[ExpiryMonth] AS [ExpiryMonth],  [Extent1].[ExpiryYear] AS [ExpiryYear] FROM [dbo].[BillingDetails] AS [Extent1] WHERE [Extent1].[Discriminator] IN ('BankAccount','CreditCard') Or the non-polymorphic query for the BankAccount subclass generates this SQL statement: SELECT  [Extent1].[BillingDetailId] AS [BillingDetailId],  [Extent1].[Owner] AS [Owner],  [Extent1].[Number] AS [Number],  [Extent1].[BankName] AS [BankName],  [Extent1].[Swift] AS [Swift] FROM [dbo].[BillingDetails] AS [Extent1] WHERE [Extent1].[Discriminator] = 'BankAccount' Note how Code First adds a restriction on the discriminator column and also how it only selects those columns that belong to BankAccount entity. Change Discriminator Column Data Type and Values With Fluent API Sometimes, especially in legacy schemas, you need to override the conventions for the discriminator column so that Code First can work with the schema. The following fluent API code will change the discriminator column name to "BillingDetailType" and the values to "BA" and "CC" for BankAccount and CreditCard respectively: protected override void OnModelCreating(System.Data.Entity.ModelConfiguration.ModelBuilder modelBuilder) {     modelBuilder.Entity<BillingDetail>()                 .Map<BankAccount>(m => m.Requires("BillingDetailType").HasValue("BA"))                 .Map<CreditCard>(m => m.Requires("BillingDetailType").HasValue("CC")); } Also, changing the data type of discriminator column is interesting. In the above code, we passed strings to HasValue method but this method has been defined to accepts a type of object: public void HasValue(object value); Therefore, if for example we pass a value of type int to it then Code First not only use our desired values (i.e. 1 & 2) in the discriminator column but also changes the column type to be (INT, NOT NULL): modelBuilder.Entity<BillingDetail>()             .Map<BankAccount>(m => m.Requires("BillingDetailType").HasValue(1))             .Map<CreditCard>(m => m.Requires("BillingDetailType").HasValue(2)); SummaryIn this post we learned about Table per Hierarchy as the default mapping strategy in Code First. The disadvantages of the TPH strategy may be too serious for your design—after all, denormalized schemas can become a major burden in the long run. Your DBA may not like it at all. In the next post, we will learn about Table per Type (TPT) strategy that doesn’t expose you to this problem. References ADO.NET team blog Java Persistence with Hibernate book a { text-decoration: none; } a:visited { color: Blue; } .title { padding-bottom: 5px; font-family: Segoe UI; font-size: 11pt; font-weight: bold; padding-top: 15px; } .code, .typeName { font-family: consolas; } .typeName { color: #2b91af; } .padTop5 { padding-top: 5px; } .padTop10 { padding-top: 10px; } p.MsoNormal { margin-top: 0in; margin-right: 0in; margin-bottom: 10.0pt; margin-left: 0in; line-height: 115%; font-size: 11.0pt; font-family: "Calibri" , "sans-serif"; }

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  • Foundation CSS Framework, how to change triangle on accodion [migrated]

    - by CreateSean
    I'm using foundation framework for the first time and for the most part everything is going smoothly. I am however having some trouble with the accordion in that I need to change the open/close indicator triangle that is in use. You can see it in the docs here. I've looked through the css and found the section with the accordion on foundation.css at lines 709-719 but there is no image to change or adjust. I would like to change this icon to the one in my psd, but just can't figure out where. See attached screenshot for what needs to be changed. I know how to make changes, in this case I just can't find where to make the change.

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