Ricka on MVC & Dynamic Data

Session-less MVC Controller for MVC 2 / RC

ricka0 — Thu, 17 Dec 2009 02:42:00 GMT

LiveJournal Tags: MVC , MVC 2 , session Why a session-less controller? You have a single client making multiple concurrent requests to the server. The default behavior is these requests will be serialized; with the session-less controller they execute...(read more)

Using the BeginMethod/EndMethod pattern with MVC

ricka0 — Thu, 03 Dec 2009 01:33:00 GMT

If your asynchronous action method calls a service which exposes methods using the BeginMethod() / EndMethod() pattern , your callback will be executed on a thread which is not under the control of ASP.NET. Some consequences of this are that HttpContext.Current...(read more)

Should my database calls be Asynchronous?

ricka0 — Sat, 14 Nov 2009 01:10:02 GMT

Long running/expensive database calls might seem like a natural candidate for asynchronous calls. In my MSDN article, Using an Asynchronous Controller in ASP.NET MVC , I go out of my way to avoid suggesting DB calls are good candidates. Conventional wisdom...(read more)

Tips on getting your ASP.NET MVC questions answered quickly

ricka0 — Thu, 29 Oct 2009 21:22:00 GMT

When you run into an issue or have a question about ASP.NET MVC the best place for it is the MVC Forum . When you write your question, there are a few simple things that you can do to make it easier for the ‘experts’ to answer (and hence to get an answer...(read more)

MVC FAQ

ricka0 — Thu, 15 Oct 2009 19:43:00 GMT

Please post corrections/submissions to the MVC Forum . Include MVC FAQ in the title. Post LINQ to SQL To SQL Questions here Post Entity Framework Questions here Q: How do I get started with MVC? Walkthrough: Creating a Basic MVC Project with Unit Tests...(read more)

Client Side Validation for MVC 2 P2

ricka0 — Sat, 03 Oct 2009 02:30:00 GMT

MVC 2 Preview 1 added support for DataAnnotations . In my MSDN article How to: Validate Model Data Using DataAnnotations Attributes I covered the basics of validation. Preview 2 adds client validation with the addition of one line of code. The following...(read more)

DRY-ing out the MVC 2 Templated Helpers

ricka0 — Tue, 18 Aug 2009 22:15:00 GMT

In my MSDN article Using Templated Helpers to Display Data , I show how they provide a very productive means of building a UI for data sets. The code below shows a typical use of the Display and Label helpers. < span style =" font-weight : bold ; ">...(read more)

Using DataAnnotations in MVC 2 - Catching up to Dynamic Data

ricka0 — Sat, 01 Aug 2009 10:39:00 GMT

DataAnnotations help you write robust validation and prevent the type of annoying error message shown above. Form submittal failure when a field doesn’t validate can be very frustrating - especially when there is no indication of the problematic property...(read more)

New Templated Helpers Improve SoC

ricka0 — Fri, 24 Jul 2009 04:08:15 GMT

SoC (from WikiPedia) In my MSDN article Walkthrough: Using Templated Helpers to Display Data I show how to annotate your data model to specify that a field should be rendered with a type-specific control. The download sample code also includes a control...(read more)

Setting font attributes with UIHint in your Entity Partial Class

ricka0 — Tue, 02 Jun 2009 17:41:00 GMT

I've written a simple Field Template ( RedBold.ascx ) that reads most font attributes and applies them to your field values. The new entity templates make it easy to apply font attributes to the field labels. The image below shows several font attributes...(read more)

Dynamic Data FAQ

ricka0 — Thu, 08 Jan 2009 13:03:00 GMT

Please post corrections/new submissions to the Dynamic Data Forum. Put FAQ Submission/Correction in your title.

See Tips on getting your ASP.NET Dynamic Data questions answered quickly

Post LINQ To SQL Questions here
Post Entity Framework Questions here

Links that will answer questions:

From the Dynamic Data architect David Ebbo

From http://blogs.msdn.com/rickAndy (Most samples include VB)

Explicit connection string for EF and L2S
Custom Validation Error message not displayed
Improving the FK field display: Showing two fields in Foreign Key columns
How to create an updateable view with ADO Entity Framework and with LINQ to SQL
Tweaking the Filter Repeater When you have too many FK to display in the filter repeater.

From ASP.Net Developer David Fowler

Q: How do I get started with Dynamic Data?
A: If you like videos, see ASP.NET Dynamic Data videos
     MSDN on Dynamic Data
     Walkthrough: Creating a New ASP.NET Dynamic Data Web Site Using Scaffolding
     http://www.asp.net/dynamicdata/
     Dynamic Data Forum

Q: What's new with Dynamic Data for .Net 4 Beta? <-- New
A: See this link.

Q: The data annotation to my partial class is not working?
A: The most common problem is no namespace or incorrect namespace around your partial class. A partial class that is not part of the data model (or part of another class) is known as a naked partial class. The easiest way to test if you have a naked partial class is to add a non-existing field to the partial class. In the following snippet, bogus is not in the CustomerAddress table.

[MetadataType(typeof(CustomerAddressMetaData))]
   public partial class CustomerAddress {
       public class CustomerAddressMetaData {

           [ScaffoldColumn(false)]
           public object ModifiedDate;

           public object bogus;
       }
   }

When you run the Dynamic Data project, you will get the following exception in DefaultModel.RegisterContext (in global.asax):

The associated metadata type for type 'DynamicDataProject.CustomerAddress' contains the following unknown properties or fields: bogus. Please make sure that the names of these members match the names of the properties on the main type.

Q: How do I generate GUIDs on inserts?
A: You don't, you shouldn't. Let the DB generate them or you will have performance problems. You can modify the data model XML and explicitly state they are DB generated. With the EDM, use StoreGeneratedPattern="Computed" while Linq to SQL uses IsDbGenerated="true"

Q: How to set Displayformat for a password field?
A: See Steve's excellent Password FieldTemplates for Dynamic Data

Q: How do I check for duplicates before I insert? (Or get values from the DB for any reason before I insert)
A: see this post.

Q: How do I mark a columns as read-only?
A: see this post or Making a Field Read-Only via the ReadOnlyAttribute – Dynamic Data - Note the next version of Dynamic Data And The ASP.NET Dynamic Data 4.0 Preview 3 support the [ReadOnly(true)] attribute.

Q: Can Dynamic Data use a data model generated by a 3rd party O/RM tool?
A:The current Dynamic Data needs the following items to work with a technology:
-    Technology must support Linq
-    DataSource control must exist for the technology
-    Dynamic Data ModelProvider must exist for the technology

An example of one today is LLBLGen: http://www.llblgen.com/defaultgeneric.aspx

nHibernate currently does not meet the Linq requirements.

Q: What DB's are supported?
A: See ADO.NET Entity Framework Providers

Q: How do I hide columns from the Edit and other page templates?
A: Suppose you want to display the Salary field, but you don't want to show it in the Edit and Insert templates. See Stephens popular tutorial

Dynamic Data - Hiding Columns in selected PageTemplates

Q: How do I disallow navigation links on Foreign Key columns?
A: By default, DD displays the first string column in the Foreign Key table in stead of the FK. This is rendered as a link (NavigateUrl) to the FK table. If you're not happy with the default (column shown) use the DisplayColumn attribute on the FK table to specify which property is displayed. See also Improving the FK field display: Showing two fields in Foreign Key columns. Back to the original question. The easiest way to disable the FK property from being a NavigateUrl is to hide the FK table by annotating your entity partial class with the ScaffoldTable attribute. Note, ScaffoldTable will hide your table. If you want to expose your table but disable the hyperlink - see Stephens excellent blog Allow Navigation on ForeignKey FieldTemplate – Dynamic Data

Q: How do I move the Edit Delete Details links from the left side (column 0) to the right side of the table.
A: Create your own IAutoFieldGenerator.GenerateFields and add the command field at the end. (thx David Fowler). See this post.

Q: How do I implement role based security? (tables/columns visibility dependent on users role).
A: See this post, and custom IAutoFieldGenerator

Q: How do map stored procedures (sprocs) to Inserts and get back the auto generated PK using L2S?
A: See LINQ to SQL (Part 7 - Updating our Database using Stored Procedures) , Stored Procedures (LINQ to SQL) and How to override default insert method of Details View in Dynamic Data .

Custom Validation Error message not displayed

ricka0 — Thu, 01 Jan 2009 01:44:00 GMT

A customer pointed out that his Spanish validation error messages were not being displayed; the default Error message was shown instead. I'll use the Products table from the NorthWind Db to reproduce the problem and show a work-around.

Create a partial class for the Products entity:

 [MetadataType(typeof(ProductsMD))]
    public partial class Products {
        public class ProductsMD {
            [DataType("dummy", ErrorMessage = "El campo debe ser un entero positivo")]
            [DisplayName("En la acción")]
            public object UnitsInStock { get; set; }
        }
    }

VB

    <MetadataType(GetType(ProductsMD))> _
Public Class Products
        Public Class ProductsMD
            <DataType("dummy", ErrorMessage:="El campo debe ser un entero positivo"), _
             DisplayName("En la acción")> _
            Public Property UnitsInStock() As Object
            End Property
        End Class
    End Class

Navigate to the Products table, edit a row, and change the UnitsInStock to a letter. Select update and you will get a default error message, not the message applied with the DataType attribute.

The example above was doomed to failure as the DataType attribute above does not match the DataType enum or have a matching field template.

There are a couple of possible solutions for displaying custom validation errors on integer conversion failure. You can add the compare validator message that will be displayed for any validation error. The code should be added as the last statement of the Page_Load method in the DynamicData\FieldTemplates\Integer_Edit.ascx.cs (or .vb) file.

CompareValidator1.ErrorMessage = String.Format("El campo {0} debe ser un entero", Column.DisplayName);

or for VB

CompareValidator1.ErrorMessage = String.Format("El campo {0} debe ser un entero", Column.DisplayName)

Entering a non-integer such as Z to the units in stock field now yields the following error message:

El campo En la acción debe ser un entero

Adding the CompareValidator1.ErrorMessage to the integer template works for every scaffolded integer.

For more flexibility, you can extract the custom message from the data model partial class. Replace the CompareValidator1.ErrorMessage line above with the following in the Page_Load method.

 var dataTypeAttribute = MetadataAttributes.OfType<DataTypeAttribute>().SingleOrDefault();

 if (dataTypeAttribute != null) {
    CompareValidator1.ErrorMessage = dataTypeAttribute.FormatErrorMessage(Column.DisplayName);
 }

Dim dataTypeAttribute = MetadataAttributes.OfType(Of DataTypeAttribute)().SingleOrDefault() 

If dataTypeAttribute IsNot Nothing Then 
    CompareValidator1.ErrorMessage = dataTypeAttribute.FormatErrorMessage(Column.DisplayName) 
End If

Even simpler than adding a dummy attribute and extracting the error message; use the RegularExpression attribute and allow only positive integers. The following snippet fixes the error message problem without requiring you to extract the error message in the Page_Load method.

  [MetadataType(typeof(ProductsMD))]
    public partial class Products {
        public class ProductsMD {
  //          [DataType("dummy", ErrorMessage = "El campo debe ser un entero positivo")]
            [RegularExpression(@"^0*[1-9][0-9]*$", ErrorMessage = "Must be a entero positivo")]
            [DisplayName("En la acción")]
            public object UnitsInStock { get; set; }
        }
    }

VB

<MetadataType(GetType(ProductsMD))> _ 
Public Partial Class Products 
    Public Class ProductsMD 
Private _UnitsInStock As Object 
        ' [DataType("dummy", ErrorMessage = "El campo debe ser un entero positivo")] 
        <RegularExpression("^0*[1-9][0-9]*$", ErrorMessage := "Must be a entero positivo")> _ 
        <DisplayName("En la acción")> _ 
        Public Property UnitsInStock() As Object 
            Get 
                Return _UnitsInStock 
            End Get 
            Set(ByVal value As Object) 
                _UnitsInStock = value 
            End Set 
        End Property 
    End Class 
End Class

Notes:

We are using the DataType attribute as a dummy attribute so we can extract our custom error message when a validation error occurs.
This is a known bug that should be fixed in the next release.

Explicit connection string for EF

ricka0 — Tue, 09 Dec 2008 21:05:00 GMT

The default constructor for the ObjectContext class in the Entity Data Model (EDM) retrieves the construction string from the web.config or app.config file. If you have multiple data models or need to pass in the the construction string at run time you must use the ObjectContext constructor that takes a construction string. (Note: Be sure to see the bug/work-around at the end of this article.) The follow snippet shows how to build the string for integrated security.

//  copy connection string from app.config or web.config  

    // connectionString="metadata=res://*;
    // provider=System.Data.SqlClient;
    // provider connection string=&quot;
    // Data Source=ricka0;Initial Catalog=Northwind;Persist Security Info=True;
    // User ID=sa;Password=*(IU89iu;MultipleActiveResultSets=True&quot;"
    // providerName="System.Data.EntityClient" 
    

    public static string UglyConStr() {

        return "metadata=res://*;"
          + "provider=System.Data.SqlClient;"
          + "provider connection string=';"  // Replace &quot with ' (single quote)
        + "Data Source=ricka0;"
        + "Initial Catalog=Northwind;"
        + "Persist Security Info=True;"
        + "User ID=sa;Password=*(IU89iu;"
        + "MultipleActiveResultSets=True';"  // Replace &quot with ' (single quote)
            //    + "providerName=\"System.Data.EntityClient\""
        ;
    }

While the construction string above works, it's very ugly. The hair pulling trick to get it working is replacing &quot with a single quote ' as shown in the comments. Using the raw connection string from the config file (using &quot ) results in a misleading error message Keyword not supported: 'data source'.

A much more elegant construction string using SQL connection is shown below.

 public static string getConStrSQL() {

        string connectionString = new System.Data.EntityClient.EntityConnectionStringBuilder
        {
            Metadata = "res://*",
            Provider = "System.Data.SqlClient",
            ProviderConnectionString = new System.Data.SqlClient.SqlConnectionStringBuilder
            {
                InitialCatalog = "Northwind",
                DataSource = "ricka0",
                IntegratedSecurity = false,
                UserID = getUID(),                 // User ID such as "sa"
                Password = getPWD(),               // hide the password
            }.ConnectionString
        }.ConnectionString;

        return connectionString;
    }

In VB:

Public Shared Function getConStrSQL() As String
     Dim connectionString As String = New System.Data.EntityClient.EntityConnectionStringBuilder() _
         With {.Metadata = "res://*", _
               .Provider = "System.Data.SqlClient", _
               .ProviderConnectionString = New System.Data.SqlClient.SqlConnectionStringBuilder() _
                 With {.InitialCatalog = "Northwind", _
                       .DataSource = "ricka0", _
                       .IntegratedSecurity = False, _
                       .UserID = getUID(), _
                       .Password = getPWD()}.ConnectionString}.ConnectionString
     Return connectionString
 End Function

The integrated security approach is slightly different.

public static string getConStrIntegrated() {

        string conStrIntegratedSecurity = new System.Data.EntityClient.EntityConnectionStringBuilder
           {
               Metadata = "res://*",
               Provider = "System.Data.SqlClient",
               ProviderConnectionString = new System.Data.SqlClient.SqlConnectionStringBuilder
               {
                   InitialCatalog = "NorthwindEF",
                   DataSource = "bing0",
                   IntegratedSecurity = true,
               }.ConnectionString
           }.ConnectionString;

        return conStrIntegratedSecurity;
    }

For Dynamic Data, simply pass the construction string to the MetaModel RegisterContext as follows.

 public static void RegisterRoutes(RouteCollection routes) {
        MetaModel model = new MetaModel();


        model.RegisterContext(() => new NorthwindModel.NorthwindEntities(getConStrIntegrated()),
            new ContextConfiguration()
            {
                ScaffoldAllTables = true
            });

        // Routes omitted for clarity
    }

Unfortunately, the current version of Dynamic Data doesn't support this approach with EF (L2S does work). To get the page templates to use the connection string you must add the following line to the Page_Load method in the page templates.

GridDataSource.ContextCreating += delegate(object ceSender, System.Web.UI.WebControls.EntityDataSourceContextCreatingEventArgs ceArgs) {
            ceArgs.Context = (System.Data.Objects.ObjectContext)table.CreateContext();
        };

The complete Page_Load is below

protected void Page_Load(object sender, EventArgs e) {
        table = GridDataSource.GetTable();

         GridDataSource.ContextCreating += delegate(object ceSender, System.Web.UI.WebControls.EntityDataSourceContextCreatingEventArgs ceArgs) {
            ceArgs.Context = (System.Data.Objects.ObjectContext)table.CreateContext();
        }; 

        Title = table.DisplayName;
        GridDataSource.Include = table.ForeignKeyColumnsNames;
        InsertHyperLink.NavigateUrl = table.GetActionPath(PageAction.Insert);

        // Disable various options if the table is readonly
        if (table.IsReadOnly) {
            GridView1.Columns[0].Visible = false;
            InsertHyperLink.Visible = false;
        }
    }

Improving the FK field display: Showing two fields in Foreign Key columns

ricka0 — Sat, 22 Nov 2008 06:17:00 GMT

The default scaffold of the CustomerAddress table in the AdventureWorksLT database poses a problem: Dynamic Data (DD) defaults to using the first string field in the referenced table. In this case, the first string field is the Title field (Mr,Ms, and so on). The image below shows the problem with the FilterRepeater drop down list and Customer column elements.

We can take a first step toward fixing this issue by creating and annotating a partial class for the Customer entity. The code below now displays the LastName field for the customer entity. The DisplayColumn attribute tells referring entities which column to use for display instead of the Foreign Key field.

 [DisplayColumn("LastName")]
 [MetadataType(typeof(CustomerMetaData))]
 public partial class Customer {
      public class CustomerMetaData {
   }
 }

While the resulting view is an improvement, it’s not there yet. Note that it doesn't distinguish between the customers with non-unique last names, such as Adams or Liu.

To fix this, we overload the ToString method for the Customer partial class as shown below:

// [DisplayColumn("LastName")]
[MetadataType(typeof(CustomerMetaData))]
public partial class Customer {

     public override string ToString() {
         return LastName.ToString() + ", " + FirstName.ToString();
     }

     public class CustomerMetaData {

}

The resulting display gets it right: the code now shows the correct field, and it distinguishes between David, Jinghao and Kevin Liu.

Special thanks to David Ebbo for recommending the ToString() approach and Phil Haack for granting me blog dibs.

How to create an updateable view with ADO Entity Framework and with LINQ to SQL

ricka0 — Sat, 04 Oct 2008 05:07:00 GMT

Creating an update-able view with ADO Entity Framework (EF) or LINQ to SQL (L2S) is a fairly advanced topic and not directly associated with Dynamic Data. At the end of the article I have a sample console application to verify the modified L2S data model allows updates on a view. To create an update-able view, you must modify the wizard (or other tool) generated XML file (data model). Each time you generate a new data model (for example when the schema changes), you will need to reapply these steps.

ADO Entity Framework (EF) makes views Read Only via the <DefiningQuery> element. You make the data model view update-able by removing the <DefiningQuery> element and making a few minor changes. Note the example below is a very simple view on one table and includes the primary key.

This is what I did to make an update-able view for the AdventureWorksLT DB

CREATE VIEW [SalesLT].[vAddr]
AS
SELECT AddressID,[AddressLine1],[City],[StateProvince],[CountryRegion],[PostalCode]
FROM [AdventureWorksLT2008].[SalesLT].[Address]

The next line shows this view is update-able (at least from T-SQL)

UPDATE vAddr SET PostalCode = '54321'
WHERE addressID > 11382 AND
StateProvince = 'WA'

 (18 row(s) affected)

Edit the EF SSDL, comment out the <DefiningQuery> , remove store: prefix from Schema="SalesLT" and remove store:Name="vAddr" . The commented/changed code below

</EntityContainer>

LINQ to SQL is the simplest.

Using the view above,

Simply change the following line in the wizard generated code to use AutoSync = AutoSync.OnInsert in lieu of AutoSync=AutoSync.Always on the AddressID property.

// [Column(Storage="_AddressID", AutoSync=AutoSync.Always, DbType="Int NOT NULL IDENTITY", IsPrimaryKey=true, IsDbGenerated=true)]
[Column(Storage = "_AddressID", AutoSync = AutoSync.OnInsert, DbType = "Int NOT NULL IDENTITY", IsPrimaryKey = true, IsDbGenerated = true)]
public int AddressID

The following example shows how to test the view from a console application.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.Linq;
using System.Data.Linq.Mapping;

namespace updateableView {

        public class T {
            public LTDataContext db;
            //    readonly string con = "Data Source=bing0;Initial Catalog=AdventureWorksLT2008;Integrated Security=True";
            readonly string con = "Data Source=bing0;Initial Catalog=AdventureWorksLT2008;" +
                                   "Persist Security Info=True;User ID=sa;Password=*(IU89iu";

            public T() {
                db = new LTDataContext(con);
            }

            public void addAddr(string city) {

                vAddr adr = new vAddr();
                adr.AddressLine1 = "1234 N St.";
                adr.City = city;
                adr.PostalCode = "99966";
                adr.StateProvince = "Mt";
                adr.CountryRegion = "None";

                db.vAddrs.InsertOnSubmit(adr);
                db.SubmitChanges();
            }

            public void tq(string city) {

                Table<vAddr> addr = db.GetTable<vAddr>();
                var q = from c in addr
                        where c.City == city
                        select c;

                foreach (var cst in q)
                    Console.WriteLine("id = {0}, City = {1}", cst.AddressID, cst.City);
            }
        }

        class Program {
            static void Main(string[] args) {
                T tdb = new T();
                string city = "GF";
                tdb.addAddr(city);
                tdb.tq(city);

            }
        }
    }