如何通过反射获取和使用类/实体类型？

Question

I have these entities that are being called at runtime and I need to be able to return an IQueryable<EntityObject> based on the entity type being called that particular time by string. Let's say the entity is types of food and the class name is Food , so...

return Repository.Read<Food>();    //this is what I am trying to accomplish

However, I don't know that it is Food until runtime and is such only given as a string, so I use reflection:

Type t = Type.GetType(lookupEntityName);    //where lookupEntityName = "Food"

How can I use this Type t to replace 'Food' in the original line of code from above:

return Repository.Read<HERE>();    // use 't' to repalce "HERE"

Answer 1

Supposing that your method only contains a return statement (because you have only posted that), you could do something like this (warning: this wasn't tested):

public static IQueryable<T> Read<T>()
{
    return Repository.Read<T>();
}

And you could use it like this:

IQueryable<Food> food = Read<Food>();

Answer 2

You have to use the MethodInfo.MakeGenericMethod Method to create your generic method at runtime.

var openMethod = typeof(Repository).GetMethod(nameof(Repository.Read), ...);
var closedMethod = openMethod.MakeGenericMethod(t);
return closedMethod.Invoke(...);

Answer 3

If you need to call a generic method, you must get the MethodInfo of that function and create a generic MethodInfo for the appropiate type.

This is a helper function to do this:

public MethodInfo GetGenericMethod(string MethodName, Type SourceType, Type TargetType)
{
    var mInfo = SourceType.GetMethod(MethodName);
    return mInfo.MakeGenericMethod(TargetType);
}

And now you can do this:

Type t = Type.GetType(lookupEntityName);
Type tSrc = typeof(Repository);

var result = GetGenericMethod("Read", tSrc, t).Invoke(Repository);

If Read is an static method then pass null to the invoke.