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linq ; select ;

Linq: Select Fields in Query

16.08.2018 (👁241)


 

Error: object does not contain a definition for fieldname

Code

Description

CS1061

'object' does not contain a definition for 'IDSearchAgent' and no extension method 'IDSearchAgent' accepting a first argument of type 'object' could be found (are you missing a using directive or an assembly reference?)

 

Problem:

If you create combined data of a query in Linq, then at the end of the data query you can either completely output the data tables with all fields or make a well-defined field specification which result fields are required for the output.

This information leads to an error:

Query from join ..

select searchAgent.IDSearchAgent, asp.Email).Take(3000);

Solution:

You have to change the output to new {..} pack

select new { searchAgent.IDSearchAgent, q3.Email }).Take(3000);

 

 

Not correct:

 

Error:

Wrong field definition in the query

//--< Get Linq.Query >--

var query = (from searchAgent in _dbContext.tbl_SearchAgents

             join users in _dbContext.tbl_Users on searchAgent.IDOwner equals users.IDUser into searchagents_with_user

 

             from q2 in searchagents_with_user.DefaultIfEmpty()

             join asp in _dbContext.Users on q2.IDAspNetUser equals asp.Id into searchagents_with_user_emails

 

             from q3 in searchagents_with_user_emails.DefaultIfEmpty()

 

             orderby searchAgent.IDOwner descending, searchAgent.IDSearchAgent  descending

             select searchAgent.IDSearchAgent, asp.Email).Take(3000);

//--</ Get Linq.Query >--

 

 

Solution:

//--< Get Linq.Query >--

var query = (from searchAgent in _dbContext.tbl_SearchAgents

             join users in _dbContext.tbl_Users on searchAgent.IDOwner equals users.IDUser into searchagents_with_user

 

             from q2 in searchagents_with_user.DefaultIfEmpty()

             join asp in _dbContext.Users on q2.IDAspNetUser equals asp.Id into searchagents_with_user_emails

 

             from q3 in searchagents_with_user_emails.DefaultIfEmpty()

 

             orderby searchAgent.IDOwner descending, searchAgent.IDSearchAgent  descending

             select new { searchAgent.IDSearchAgent, q3.Email }).Take(3000);

//--</ Get Linq.Query >--

 

 

 

Linq is the modern creation of SQL queries in collaboration with EF EntityFramework.