How to set an Entity Framework query equal to a string

Question

I'm very new to Entity Framework. I'm trying to use it to query the database, and I want to set a string equal to the result of that query.

Here's the code I'm using:

string UserId = (db.StudentModel.Where(b => b.UserName == strCert)).ToString();

Now, obviously this sets UserId equal to the query. How do I set UserId equal to the result?

Am I incorrect in using the linq tag? I just want to use that query that I have above to get a cell from the database. The text in that cell is what I need UserId to store. — Kulahan
– Kulahan, Commented Jul 28, 2014 at 22:28

har07 · Accepted Answer · 2014-07-29 00:27:27Z

2

Do you mean something like this :

string UserId = db.StudentModel.FirstOrDefault(b => b.UserName == strCert).UserId;

or more safely :

var student = db.StudentModel.FirstOrDefault(b => b.UserName == strCert);
if(student != null) 
{
    string UserId = student.UserId;
    /* do something with UserId here */
}

edited Jul 29, 2014 at 0:27

answered Jul 28, 2014 at 22:30

har07

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7 Comments

clarkitect Over a year ago

This is an excellent implementation but I don't see the value added in line 2.

Kulahan Over a year ago

Two questions: 1) when I use this, it's giving me a 'cannot implicitly convert int to string' error - I don't even know what the int would be! 2) Can you explain why UserId goes at the end of the command?

clarkitect Over a year ago

It's starting to look like UserId is of type int rather than the inexplicable string type that OP's sample code includes :D

har07 Over a year ago

1) you need to add .ToString() (edited my code as I didn't know before that UserId is of type int). 2) the query return a StudentModel -I guess the exact type- and you want only UserId property of that model, that's why .UserId at the end is required

Kulahan Over a year ago

WELL THAT'S EMBARRASSING. You're right. It's an int in the database. Much appreciated for pointing that out! hahaha

|

Sergey Boiko · Accepted Answer · 2014-07-28 22:42:17Z

1

use this:

db.StudentModel.FirstOrDefault(b => b.UserName == strCert).UserId

but would be better to get object and check for null

var user = db.StudentModel.FirstOrDefault(b => b.UserName == strCert);

edited Jul 28, 2014 at 22:42

answered Jul 28, 2014 at 22:30

Sergey Boiko

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1 Comment

pollirrata Over a year ago

you will need to check if query returns null to avoid exception

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