CODEWITHSUNDEEP
c#linq
Nate Pet
Nate Pet

Reputation: 46282

Convert String to Float in LINQ

I have the following LINQ Query. Note that DataValue is a string value. I am trying to convert it to a float and then get the average. 

var Avg = (from fd in DataContext.FormData
           select float.Parse(fd.DataValue)).Average();

I get the following error:

System.NotSupportedException: 'LINQ to Entities does not recognize 
the method 'Single Parse(System.String)' method, and this method 
cannot be translated into a store expression.'

Is there a good work around to this issue?

Upvotes: 1

Views: 1513

Answers (2)

Tarek
Tarek

Reputation: 1279

Not every C# function is a mapped function to SQL. Depending on the ORM you are using (I'm assuming EntityFframework), you can find a list of mapped functions in the ORM documentation.

Mapped function basically mean a C# function that the ORM maps/converts to an SQL function and add it to the end result SQL statement that gets executed by the ORM.

Read the documentation to be safe.

If you still want to use Float.Parse, then your only option is to materialize the query first then Parse, then Average. But that is not recommended.

Upvotes: 1

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 726919

You should be able to use Convert.ToSingle instead of float.Parse:

var Avg = DataContext.FormData
    .Select(fd => DataContext.FormData(fd.DataValue))
    .Average();

Upvotes: 2

Related Questions