Trying to use a generic with Entity Framework

c#, entity-framework, generics

Solution

If you use `Expression<Func<T, bool>>` instead of `A` like this:

public interface IRepository<T>
{
    ... // other methods
    IEnumerable<T> FindBy(Expression<Func<T, bool>> predicate);
}

You can query the type using linq and specify the query in the code which calls the repository class.

public IEnumerable<SomeClass> FindBy(Expression<Func<SomeClass, bool>> predicate)
{
    return _context.Set<SomeClass>().Where(predicate);
}

And call it like this:

var results = repository.FindBy(x => x.Name == "Foo");

And given that it's a generic expression, you don't have to implement it in each repository, you can have it in the generic base repository.

public IEnumerable<T> FindBy(Expression<Func<T, bool>> predicate)
{
    return _context.Set<T>().Where(predicate);
}

Problem

Let me start with, I am not sure if this is possible. I am learning generics and I have several repositories in my app. I am trying to make an Interface that takes a generic type and converts it to something that all of the repositories can inherit from. Now on to my question. ``` public interface IRepository<T> { IEnumerable<T> FindAll(); IEnumerable<T> FindById(int id); IEnumerable<T> FindBy<A>(A type); } ``` Is it possible to use a generic to determine what to find by? ``` public IEnumerable<SomeClass> FindBy<A>(A type) { return _context.Set<SomeClass>().Where(x => x. == type); // I was hoping to do x.type and it would use the same variable to search. } ``` To clarify a little better I was considering to be a string, int or whatever type I wanted to search for. What I am hoping for is I can say x.something where the something is equal to the variable passed in. I can set any repository to my dbcontext using the ``` public IDbSet<TEntity> Set<TEntity>() where TEntity : class { return base.Set<TEntity>(); } ``` Any Suggestions?

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