CODEWITHSUNDEEP
codefluent
Greg Delaney
Greg Delaney

Reputation: 81

value from database computed property is Null in codefluent entity property

My MS SQL 2014 database table has a computed property column which uses a database function. Using SQL Server Management Studio, a query against the table lists the computed property values as expected.

The Codefluent model created via the import wizard shows the Entity with the computed column as a property. The underlying .cpf file defines the property with "d3p1:compute=" and the list of parameters that are used by the database function.

When an entity or the collection of entities is loaded, the properties which are used in the computed property have values, yet the computed property has a value of nothing/null.

How do I get Codefluent to read the computed value from the database table and have the value included in the entity's properties?

Upvotes: 2

Views: 158

Answers (2)

Dave
Dave

Reputation: 659

If Simon Mouriers solution solves your problem than that is probably the best approach. However, there are 2 other options

  1. RAW View Method

After you create a Codefluent Entities View click on the Edit Where button and it will allow you to create a RAW View

enter image description here

You can than specify the advanced property "UsedForMethods".

WARNING: Related entities will use the table instead of the view. This is by design and there is an article somewhere on the knowledge center on how to get around it. http://www.softfluent.com/product/codefluent-entities/knowledge-center/

enter image description here

  1. Rename SQL Tables and Create a SQL View with the Same Name as the Original Table - This method is a hack, Softfluent discourages this approach, I love it because I know exactly what is happening under the scenes. I have used it with success in a scenario in which I needed soft deletes. I have automated the process with 2 stored procedures that handle the renaming. Using this approach requires running one of the stored procedures to undo the name changing prior to building the model. The other stored procedure handles the renaming after building the model. I'll post the stored procedures and how I use them within a couple of days.

Upvotes: 1

Simon Mourier
Simon Mourier

Reputation: 139075

This is a bit tricky. First of all, you should declare the property like any other property. Then you must instruct the SQL producer to declare a formula on that column. You can do that with a custom 'compute' attribute in the SQL producer namespace. You can set it with the Visual Studio modeler like this:

enter image description here

In this example I've created an int property that is just another column value multiplied by 2.

Optionally, you can declare the property to be 'read on save' because most of the time, you want to read the computed value after a save, not only on load operations:

enter image description here

Once this is all done, this sample console app should display 30:

class Program
{
    static void Main(string[] args)
    {
        var c = new Customer();
        c.Name = "killroy";
        c.Age = 15;
        c.Save();
        Console.WriteLine(c.Age2); // will display 30
    }
}

Upvotes: 1

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