How can I convert string into int without enumerating a query

Question

Probably I'm blind, but I can't find how to convert string to int. I wrote

query.OrderByDescending(a => SqlFunctions.IsNumeric(
    a.Index.Substring(a.Index.Length - 4, 4)) == 1 ?
    Convert.ToInt32(a.Index.Substring(a.Index.Length - 4, 4)) :
    0);

But, as I suspected, it returns an error

LINQ to Entities does not recognize the method 'Int32 ToInt32(System.String)'

Moreover SqlFunctions don't have a member Convert. Is any way to achieve this without enumerating the query?

EDIT: int.Parse throws

LINQ to Entities does not recognize the method 'Int32 Parse(System.String)

@SriramSakthivel: It was possible that LINQ to Entities knew about int.Parse but not about Convert.ToInt32. That appears not to be the case, but it was at least possible. — Jon Skeet
– Jon Skeet, Commented Apr 22, 2015 at 13:04
This issue is a bit frustrating. I ran into it just yesterday afternoon. One thing that you have to keep in mind is that EF has to be able to generate the SQL regardless of the provider. For example, the generated SQL may be different between SQL Server and MySQL. It has to be generic enough that it can handle all situations. — Jason Richmeier
– Jason Richmeier, Commented Apr 22, 2015 at 13:07

Jason Richmeier · Accepted Answer · 2015-04-22 13:13:19Z

4

This is a long shot as I have not tried it myself (I read about it a few weeks ago).

If the SqlFunctions class does not provide a function that you need, you can create a custom function on the SQL Server side and then create a class on the .NET side similar to the SqlFunctions class to call the custom function. There is an attribute that you have to decorate the .NET class with.

Perhaps something like this would work?

You can read more about this here and here.

edited Apr 22, 2015 at 13:13

answered Apr 22, 2015 at 13:04

Jason Richmeier

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2 Comments

Marcin J Over a year ago

this sounds nice, but like a workaround quite common problem. If no one knows any shorter way that will be the answer.

xanatos Over a year ago

@MarcinJ Note that if you are using code first instead of edm files, you have to do like stackoverflow.com/a/23658354/613130

Nagaraj S · Accepted Answer · 2015-04-22 12:55:44Z

0

int a=int.Parse(string);

is the way you can convert a string into int in c#

edited Apr 22, 2015 at 12:55

Nagaraj S

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answered Apr 22, 2015 at 12:54

xNeyte

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Comments

BenM · Accepted Answer · 2015-04-22 12:56:23Z

0

int.TryParse(X.Number, out tmp) ? tmp : 0

answered Apr 22, 2015 at 12:56

BenM

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Comments

BIBD · Accepted Answer · 2015-04-22 19:58:24Z

0

Have you tried it with TryParse? something like this:

int number;
query.OrderByDescending(a =>(
                        int.TryParse(a.Item1.Substring(1, 2), 
                                        out number) == true  ? number: 0));

I always use TryParse with lambda expressions.

edited Apr 22, 2015 at 19:58

BIBD

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answered Apr 22, 2015 at 13:17

paulofer85

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3 Comments

JNYRanger Over a year ago

This does not provide an answer to the question. To critique or request clarification from an author, leave a comment below their post - you can always comment on your own posts, and once you have sufficient reputation you will be able to comment on any post.

paulofer85 Over a year ago

@JNYRanger ok i wanted to comment his post but i realize that i don t have enough reputation. I thought it was one possible solution to his question. I ll ve it in mind for next time.

BIBD Over a year ago

Sorry, @JNRanger - I think its a reasonable attempt at an answer.

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