C# – How to use UDF output as LINQ to SQL entity class property value

cdesignerlinq-to-sqluser-defined-functions

Just starting out with LINQ to SQL (you can probably tell – be gentle).

I'd like to use the value returned by a user-defined function as an entity class property value and have the the value populated when all the other basic (column) fields are loaded.

I know there are ways to use the UDF from a L2S query (here, and here), but I'd prefer to have the value automatically loaded.

For example, I'd expect LINQ to SQL to generate SQL similar to this and populate a property on my User entity class called AssociatedRecordCount with the integer value returned by GetAssociatedRecordCount:

SELECT ID, dbo.GetAssociatedRecordCount(ID) As AssociatedRecordCount
FROM Users

Also, I'm using the Visual Studio LINQ to SQL designer.

Thank you!

Best Answer

Try to create a new custom property not associated with the database and call the function (added to the context) in the getter.

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.net – Entity Framework vs LINQ to SQL

LINQ to SQL only supports 1 to 1 mapping of database tables, views, sprocs and functions available in Microsoft SQL Server. It's a great API to use for quick data access construction to relatively well designed SQL Server databases. LINQ2SQL was first released with C# 3.0 and .Net Framework 3.5.

LINQ to Entities (ADO.Net Entity Framework) is an ORM (Object Relational Mapper) API which allows for a broad definition of object domain models and their relationships to many different ADO.Net data providers. As such, you can mix and match a number of different database vendors, application servers or protocols to design an aggregated mash-up of objects which are constructed from a variety of tables, sources, services, etc. ADO.Net Framework was released with the .Net Framework 3.5 SP1.

This is a good introductory article on MSDN: Introducing LINQ to Relational Data

C# – How to lazy-load a single property on a Linq entity

I've dissected the results of the designer's generated code.

Step 1: Create a private member using the System.Data.Linq.Link type:

private System.Data.Linq.Link<String> _columnName;

Step 2: Set the Storage parameter of the Column attribute to this member name, and fill in the property getter and setters:

[Column(Name = "column_name", Storage = "_columnName"...]
public String ColumnName 
{
    get
    {
        return _columnName.Value;
    }
    set
    {
        _columnName.Value = value;
    }
}

Best Answer

Related Solutions

.net – Entity Framework vs LINQ to SQL

C# – How to lazy-load a single property on a Linq entity

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