How can I call local method in Linq to Entities query?

Question

How can I call local method in Linq to Entities query?

.net c# entity-framework linq

Question

I have the following code:

public void SalesCount(string customerId)
{
  ..
  ..
  return ...;
}

var resultQuery = dataContext.Customers
.Where (c => c.Name == "Alugili")
.Where (c => SalesCount(c.CustomerId) < 100);

When I execute resultQuery I get a translation to SQL exception.

I need to call SalesCount in the Where can I do that is there any workaround for this problem!

Bassam Alugili

Popular Answer

Try

var resultQuery = dataContext.Customers
.Where (c => c.Name == "Alugili")
.ToArray()
.Where (c => SalesCount(c.CustomerId) < 100);

But then the second Where is not run as SQL but locally - all customers with the name "Alugili" are pulled from the DB...

Otherwise you have to write out your method directly in the where method as lambda expression.

Rico Suter

View more on Stack Overflow

xanatos · Accepted Answer · 9/10/2013 9:20:36 AM

Simply you can't. You can't execute C# code on the SQL server directly, you can use only Expressions and some special recognized functions...

Unless you transform your query (at least partially) in a LINQ-to-Objects...

var resultQuery = dataContext.Customers
    .Where (c => c.Name == "Alugili")
    .AsEnumerable()
    .Where (c => SalesCount(c.CustomerId) < 100);

Be aware that the last Where will be executed on the client side, so many useless rows will be fetched from the DB.

How can I call local method in Linq to Entities query?

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Accepted Answer

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