How to map exisiting sql server view with EF code first - entity-framework

Question

i am fairly new in EF and learning EF code first. i am looking for a knowledge to map exisiting sql server view with EF code first. i have map my view with POCO but getting the below error.
when i try to fetch data from view then got the below error thrown
Additional information: The model backing the 'TestDBContext' context
has changed since the database was created. Consider using Code First
Migrations to update the database
my full code as follow
public class TestDBContext : DbContext
{
public TestDBContext()
: base("name=TestDBContext")
{
}
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Configurations.Add(new vwCustomerConfiguration());
}
public DbSet<vwCustomer> vwCustomer { get; set; }
}
public class vwCustomerConfiguration : EntityTypeConfiguration<vwCustomer>
{
public vwCustomerConfiguration()
{
this.HasKey(t => t.CustomerID);
this.ToTable("vwCustomer");
}
}
public class vwCustomer
{
public int CustomerID { get; set; }
public string FirstName { get; set; }
}
this way i am trying to load data.
using (var db = new TestDBContext())
{
var listMyViews = db.vwCustomer.ToList();
}
guide me what i am missing in code for which error is throwing. thanks
UPDATE1
When i issue Add-Migration "My_vwCustomer" then i saw new migration code added as below one. it seems there is no migration is pending.
public partial class My_vwCustomer : DbMigration
{
public override void Up()
{
CreateTable(
"dbo.vwCustomers",
c => new
{
CustomerID = c.Int(nullable: false, identity: true),
FirstName = c.String(),
})
.PrimaryKey(t => t.CustomerID);
}
public override void Down()
{
DropTable("dbo.vwCustomers");
}
}

Answer 1

OP's Feedback :
When i generate the view with ADO.Net Entity model wizard then
everything works fine.
You can do it as shown below.
Note : I have picked the 1 to 4 from this post.
Create a POCO class for the view; for example FooView
Add the DbSet property in the DbContext class
Use a FooViewConfiguration file to set a different name for the view
(using ToTable("Foo"); in the constructor) or to set particular
properties
public class FooViewConfiguration : EntityTypeConfiguration<FooView>
{
public FooViewConfiguration()
{
this.HasKey(t => t.Id);
this.ToTable("myView");
}
}
Add the FooViewConfiguration file to the modelBuilder, for example
ovveriding the OnModelCreating method of the Context:
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Configurations.Add(new FooViewConfiguration ());
}
According to the above configuration,now your table is
this.ToTable("myView");.In other words myView.
Here is the EF query to retrieve all the data on the myView table.
var listMyViews = yourDbContext.myView.ToList()
Your projection may be like this :
var query = yourDbContext.myView
.Select(v=> new
{
ID = v.ID,
EmpName = v.EmpName,
Salary = v.Salary
}).ToList();

Answer 2

Configure view as a table and use this custom generator to prevent migration generation for tables marked as views
public class SkipViewGenerator: CSharpMigrationCodeGenerator
{
protected override void Generate(CreateTableOperation operation, IndentedTextWriter writer)
{
if (!IsView(operation.Name))
base.Generate(operation, writer);
}
protected override void Generate(RenameTableOperation operation, IndentedTextWriter writer)
{
if (!IsView(operation.Name))
base.Generate(operation, writer);
}
protected override void Generate(MoveTableOperation operation, IndentedTextWriter writer)
{
if (!IsView(operation.Name))
base.Generate(operation, writer);
}
protected override void Generate(DropTableOperation operation, IndentedTextWriter writer)
{
if (!IsView(operation.Name))
base.Generate(operation, writer);
}
protected override void Generate(AddColumnOperation operation, IndentedTextWriter writer)
{
if (!IsView(operation.Table))
base.Generate(operation, writer);
}
protected override void Generate(DropColumnOperation operation, IndentedTextWriter writer)
{
if (!IsView(operation.Table))
base.Generate(operation, writer);
}
protected override void Generate(DropPrimaryKeyOperation operation, IndentedTextWriter writer)
{
if (!IsView(operation.Table))
base.Generate(operation, writer);
}
protected override void Generate(AlterColumnOperation operation, IndentedTextWriter writer)
{
if (!IsView(operation.Table))
base.Generate(operation, writer);
}
protected override void Generate(AddPrimaryKeyOperation operation, IndentedTextWriter writer)
{
if (!IsView(operation.Table))
base.Generate(operation, writer);
}
protected override void Generate(AlterTableOperation operation, IndentedTextWriter writer)
{
if (!IsView(operation.Name))
base.Generate(operation, writer);
}
protected override void Generate(CreateIndexOperation operation, IndentedTextWriter writer)
{
if (!IsView(operation.Name))
base.Generate(operation, writer);
}
protected override void Generate(DropIndexOperation operation, IndentedTextWriter writer)
{
if (!IsView(operation.Name))
base.Generate(operation, writer);
}
private bool IsView(string tableNameWithSchemaName)
{
var tableName = DatabaseName.Parse(tableNameWithSchemaName).Name;
var schemaName = DatabaseName.Parse(tableNameWithSchemaName).Schema;
return schemaName.Contains("View");
}
}
Usage example
internal sealed class Configuration : DbMigrationsConfiguration<MyDbContext>
{
public Configuration()
{
AutomaticMigrationsEnabled = false;
CodeGenerator = new SkipViewGenerator();
}
protected override void Seed(MyDbContextcontext)
{
// This method will be called after migrating to the latest version.
// You can use the DbSet<T>.AddOrUpdate() helper extension method
// to avoid creating duplicate seed data.
}
}
DatabaseName.Parse implementatnion you can get from Github sources