CODEWITHSUNDEEP
c#asp.netentity-framework
Johan
Johan

Reputation: 35213

"Interface name is not valid at this point"

public IEnumerable<decimal> SomeKeys
{
    get
    {
        return dbContext.SomeTable.Select(x=>x.Key);
    }
}

public IEnumerable<decimal> SomeOtherKeys
{
    get
    {
        var ret = IEnumerable<decimal>(); // interface name is not 
                                          // valid as this point
        // do stuff with ret
        return ret;
    }
}

With my current code, I'm getting the exception above.

Do I have to return a List<decimal>? Or how am I supposed to return the IEnumerable or IQueriable datatypes?

Upvotes: 3

Views: 12668

Answers (3)

Claudio Redi
Claudio Redi

Reputation: 68440

You create class instances but never interfaces as they are just code contracts but can't be instantiated.

You have to pick the collection implementing IEnumerable<T> that suit better for your scenario and stick with it.

Your property SomeOtherKeys can keep the signature, no need to change it as using an interface as return value is totally valid and a good practice as helps to reduce coupling

Upvotes: 1

rsbarro
rsbarro

Reputation: 27349

In your SomeOtherKeys property getter, you have to instantiate a class that implements the IEnumerable<decimal> interface.

Changing to List<decimal> would be fine.

var ret = new List<decimal>();
ret.Add(1.0M);
ret.Add(2.0M);

Upvotes: 1

Tigran
Tigran

Reputation: 62276

This is var ret = IEnumerable<decimal>(); just not valid C# code, that is.

You may want to do something like: 

var ret = new List<decimal>();

Remeber that List, quoting documentation, derives from IEnumerable<T> too.

public class List<T> : IList<T>, ICollection<T>, 
    IList, ICollection, IReadOnlyList<T>, IReadOnlyCollection<T>, IEnumerable<T>, 
    IEnumerable

so the code like

public IEnumerable<decimal> SomeOtherKeys
{
    get
    {
        var ret = new List<decimal>();                                          
        // do stuff with ret
        return ret;
    }
}

is perfectly valid.

Upvotes: 11

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