Entity framework query without lambda expression

Question

So I'm writing a 'semi-generic' class that fits the same pattern over and over again with the signature

public class BaseSupportRepo<TEntity, TDto> where TEntity : class where TDto : class

All of the repos that use this class have one property which is Name

What I want to do is write a function that will return a .Single() if a name matches some input (however name is not a primary key).

Now if this was a non generic function it'd be easy since

.Single(g => g.Name == name)

However because this is a generic function the .Name property cannot be used since TEntity may not have any property Name.

Is there any function in EF that can allow something akin to :-

.Single(string key, string value)

This would allow me to get around this requirement.

Why not just create a INamedEntity { string Name } and where TEntity : INamedEntity and make all your entities implement TEntity — Carlos Muñoz
– Carlos Muñoz, Commented Jan 5, 2015 at 19:37

Carlos Muñoz · Accepted Answer · 2015-01-05 20:29:06Z

5

Create interface:

public interface IEntityWithName
{
    string Name { get; set;}
}

And change Your repo to:

public class BaseSupportRepo<TEntity, TDto> where TEntity : class, IEntityWithName 
                                            where TDto : class

If You have a generated code using edmx file you can change your T4 template that generates Your classes to implement IEntityWithName or create partial classes like this:

public partial class SomeEntity : IEntityWithName
{
}

You can then write a query that can use Name

edited Jan 5, 2015 at 20:29

Carlos Muñoz

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answered Jan 5, 2015 at 19:36

Grzegorz W

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2 Comments

nyxthulhu Over a year ago

Unfortunately I can't get at the Entity classes since they are generated using a tool :|

Carlos Muñoz Over a year ago

If entities are partial classes you can put the interface in a partial class on your own file

Community · Accepted Answer · 2017-05-23 11:50:56Z

0

Take a look at this story: Where can I find the System.Linq.Dynamic dll?. Dynamic.cs was written by someone at Microsoft I believe and it allows you to write Linq queries using strings rather than lambdas. It has come in handy for me in the project I'm currently working on.

edited May 23, 2017 at 11:50

CommunityBot

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answered Jan 5, 2015 at 19:40

GBreen12

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