Convert Method. "The specified method on the type cannot be translated into a LINQ to Entities store expression"

Question

I'd migrated my entity 6.0 project from SQL Server to PostGreSQL. With SQL Server, these kind of convertion on my queries used to work properlly

Module.cs

return (
    from m in objDB.Modules
    orderby m.ID
    select new
    {
        ID = m.ID,
        Name = m.Name,
        Status = DB_Function.Convert.ToInt32( m.Status )
    }
);

PS: Status is a boolean type

DB_Function.cs

[System.Data.Entity.DbFunctionAttribute( "Business.Database", "ToInt32" )]
public static Int32 ToInt32( Boolean Val )
{
    return System.Convert.ToInt32( Val );
}

However, when I migrated to PostgreSQL (and therefore changed my EDMX), these kind of conversion don't execute anymore:

The specified method 'Int32 ToInt32(Boolean)' on the type 'DB_Function+Convert' cannot be translated into a LINQ to Entities store expression.

This error is related with PostGre (like int4 and not int32) or I'm missing something?

Thanks in advance.

Not an answer to your question, but why are you converting to `Int32` if `Status` is a boolean? — DavidG, Jun 11 '15 at 14:03
Because I need it with 0 and 1. In SQL Server, there is no type boolean, just bit, so this conversion was just for the bit value became int32. Although, in PostGre there is a type boolean, but all the code was programmed to work with 0 or 1, so I'm trying not to modify it drastically. — BernardoMorais, Jun 11 '15 at 14:09
Could you change the method to be `return Val ? 1 : 0;` instead? — DavidG, Jun 11 '15 at 14:11
I try with this but still returning the same error message. Now I'm with more doubts, i thought that your solution would fit like a glove. Maybe the problem is with the calling of the method. Thanks anyway for that. Edit: I have modified the linq itself and works. Thanks a lot — BernardoMorais, Jun 11 '15 at 14:17
Not to change the subject, but if you used a bit field in Sql Server, it would have by mapped it to a boolean for you in Entity Framework. And the function you have should work (I think, never used postgres with EF) *IF* postgres has a function called "ToInt32". Did you not create that function in the database? — Robert McKee, Jun 11 '15 at 15:45
I guess that I didn't undestand your comment but yes, that method that I shown was created by me. There is no native "ToInt32" even with SQL Server. — BernardoMorais, Jun 11 '15 at 16:01

score 0 · Accepted Answer · edited May 23 '17 at 10:26

0

For understanding what type of functions we can use inside LINQ to Enitities : go through below linK : linq to entities doesn't recognize a method

Now In this particular case we were having a function in side LINQ to Entites, which was unable to be translated to SQL Query and hence the Exception was thrown. SO by removing the function it work perfectly.

return ( from m in objDB.Modules orderby m.ID select new { ID = m.ID, Name = m.Name, Status = m.Status == true ? 1 : 0 } );

edited May 23 '17 at 10:26

Community

1
1

answered Jun 11 '15 at 14:12

Dreamweaver

1,328
11
21

While this may answer the question it would be helpful for the asker if you included comments in your code and/or include an additional explanation instead of providing a code-only answer. – JNYRanger Jun 11 '15 at 15:03
Additional explanation would improve your answer. – ryanyuyu Jun 11 '15 at 15:16
Yea sure will keep in mind.. next time onwards.. currently editing the answer with comment:) – Dreamweaver Jun 11 '15 at 18:51

score -1 · Answer 2 · answered Jun 11 '15 at 14:29

-1

Just remove your function and it will work if your values is not nullable

return (
from m in objDB.Modules
orderby m.ID
select new
   {
    ID = m.ID,
    Name = m.Name,
    Status = Convert.ToInt32( m.Status )
   }
);

If it is nullable you will need to check if it has value:

return (
from m in objDB.Modules
orderby m.ID
select new
   {
    ID = m.ID,
    Name = m.Name,
    Status =m.Status.HasValue? Convert.ToInt32( m.Status ):0
   }
);

answered Jun 11 '15 at 14:29

Yuri

2,820
4
28
40

With this, the same message is shown: **" LINQ to Entities does not recognize the method 'Int32 ToInt32(Boolean)' method, and this method cannot be translated into a store expression. "** That exactly why I've created the **"ToInt32( Boolean Val )"** method that I comment above. With these method it works on SQL but no with PostGre (or at least, no with the new modified EDMX that I had to created to PostGre works). Thanks anyway. – BernardoMorais Jun 11 '15 at 16:01

Convert Method. "The specified method on the type cannot be translated into a LINQ to Entities store expression"

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