使用实体框架返回要迭代的数据表

Question

I am currently using EF 6 to do the following. Execute a stored procedure, then bring in the data I need to use. The data is usually 30-40 rows per application run.

I then iterate over the var, object, table (whatever you would like to call it), performing similar (sometimes different) tasks on each row. It works great. I am able to create an Entity object, expose the different complex functions of it, and then create a var to iterate over.

Like:

foreach (var result in StoredProcedureResult)
{
string strFirstname = result.FirstName
string strLastName = result.LastName
//more logic goes here using those variables and interacting with another app

}

I recently thought it would be cool if I had a class solely for accessing the data. In this way, I could just reference that class, toss the corresponding connection string into my app.config, and then I can keep the two sets of logic separate. So when attempting to do the above in that structure, I get to the point at which, you can't return a var, or when I attempt to match object return type. The return type of the execution of a stored procedure is object (which I can't iterate on).

So my question is, how does one get to the above example, except, the var result, get returned from this data access class?

If I am missing something, or its not possible because I am doing this incorrectly, do let me know. It appeared right in my head.

Answer 1

I'm not going to describe the architecture in full. But based on your comments you can do the following (this is not the definitive nor the only way how to do it):

1. in your data access project you keep the DBContext class, all the code for the stored procedure call and also the class that defines the result of the SP call, let's call it class A;
2. in your shared layer project - I would suggest calling it Service layer - you can create a XYService class, that has a method eg GetListOfX that connects to the DB and calls the procedure, if needed this method can also perform some logic, but more importantly: it doesn't return class A, but returns a new class B (this one is defined in the service layer, or can be defined in yet another project - that might be the true shared/common project; as it would be just a definition of common structures it isn't really a layer);
3. in your application layer you work only with the method GetListOfX of the XYService and the class B, that way you don't need a reference to the data access project

In a trivial case the class B has the same properties as the class A. But depending on your needs the class B can have additional properties/functionality it can also ignore some properties of A or even combine multiple properties into one: eg combining the FirstName and LastName as one property called simply Name .

Basically what you are looking for is the multi-tier application architecture (usually 3-4 tier). The full extent of such approach (which includes heavy usage of concepts like interfaces and dependency injection) might not be suitable or needed based on your goals, eg if you are building just a small application for yourself with a couple of functions or you know there won't be any reuse of the components of the final solution, then this approach is too wasteful and you can work faster with everything in one project - you should still apply principles like SOLID , DRY and Separation of concerns .