Entity Framework Constructor Error [duplicate]

Question

I have this segment of code selecting one column from a table which works fine:

db.Database.SqlQuery<string>("select Col1 from ....).ToList();

However, as expected when trying to select more than one column it errors as the result structure is incorrect.

I've tried the following:

db.Database.SqlQuery<Tuple<string, string>>("select Col1, Col2 from ...).ToList();

Which returns the error:

The result type 'System.Tuple`2[System.String,System.String]' may not be abstract and must include a default constructor.

How can I fix this, Am I correct to be using Tuple?

How about using a class (with the properties you select in the query) instead of Tuple? — Developer
– Developer, Commented Jan 12, 2017 at 12:44
try string[] just a guess.... dont think it would work... class is much better — Seabizkit
– Seabizkit, Commented Jan 12, 2017 at 12:45

user4622594 · Accepted Answer · 2017-01-12 12:47:26Z

3

Define a class for your query result e.g.

class QueryResult
{
    public string Col1 { get; set; }
    public string Col2 { get; set; }
}

and query like this:

db.Database.SqlQuery<QueryResult>("select Col1, Col2 from ...).ToList();

answered Jan 12, 2017 at 12:47

user4622594

Sign up to request clarification or add additional context in comments.

1 Comment

Cory Over a year ago

Thanks! This has resolved my issue.

Ghasan غسان · Accepted Answer · 2017-01-12 12:46:38Z

3

You need to have a class that contains properties that have the same name of your columns in order for Database.SqlQuery to work. See here.

public class MyType
{
    public string Col1 { get; set; }
    public string Col2 { get; set; }
}

List<MyType> list = db.Database.SqlQuery<MyType>("select Col1, Col2 from ....").ToList();

answered Jan 12, 2017 at 12:46

Ghasan غسان

5,9254 gold badges37 silver badges47 bronze badges

1 Comment

Jack Over a year ago

Yeah, I think the more important thing is you have to make sure the properties have the same name with your query columns.

Collectives™ on Stack Overflow

Entity Framework Constructor Error [duplicate]

2 Answers 2

1 Comment

1 Comment

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

1 Comment

Linked

Related