CODEWITHSUNDEEP
c#linq
Volatil3
Volatil3

Reputation: 14998

How to perform Data Type Converion in LINQ?

I have a query given below in which I want to convert it's type.

Select
CONVERT(date, o.OrderDate)as OrderDate
From Orders

I am writing following statement:

var r= (
                    from o in db.Orders
                    select new { o.OrderNumber,o.Name,o.State,Convert.ToDateTime(o.OrderNumber) }
                ).ToList();

So it gives error:

Error 18 Invalid anonymous type member declarator. Anonymous type members must be declared with a member assignment, simple name or member access.

How do I deal with this conversion?

Upvotes: 2

Views: 119

Answers (4)

Mike
Mike

Reputation: 2601

Try

var r= (from o in db.Orders
    select new { o.OrderNumber,o.Name,o.State,
                 OrderDate = Convert.ToDateTime(o.OrderDate) }
                ).ToList();

Edit

Try this to materialize the query first.

var query = db.Orders.ToList().Select(o => new {
o.OrderNumber,
o.Name,
o.State,
OrderDate = Convert.ToDateTime(o.OrderNumber)
}).ToList();

Upvotes: 1

sakura-bloom
sakura-bloom

Reputation: 4594

When you execute your LINQ to Entities query it is converted to an equivalent database-side code using the underlying data provider.

It so happens that there is no mapping from Convert.ToDateTime() to SQL Server equivalent.

Instead, you would do this in memory after you've retrieved the data as follows.

var r= 
    (from o in db.Orders
    select new { o.OrderNumber, o.Name, o.State })
    .AsEnumerable() // Execute the above query
    .Select(order => new { order.OrderNumber, order.Name, order.State, OrderDate = Convert.ToDateTime(order.OrderNumber)})
    .ToList();

(You could also split this into two queries for readability.)

There are also functions you can use in your L2E queries that are converted to their database equivalents.

See the SqlFunctions and the EntityFunctions classes for more information.

Upvotes: 0

nvoigt
nvoigt

Reputation: 77354

You need to name the members of your anonymous type. Sometimes the compiler will pick a name automatically (for example when you are assigning properties), but sometimes, it's not possible:

                                            vvvv
 new { o.OrderNumber, o.Name, o.State, OrderDateTime = Convert.ToDateTime(o.OrderNumber) }

Upvotes: 1

Tigran
Tigran

Reputation: 62296

That's mean that you need to assign names to the values of that anonymous memeber.

For example: 

from o in db.Orders
select new { OrderNumber = o.OrderNumber, Name = o.Name,
            State = o.State, Date = Convert.ToDateTime(o.OrderNumber) }

Upvotes: 1

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