Business logic layer needs its own models or not

Question

I'm doing 3 tier application using asp.net mvc and I want to do everything as recommended.

So I've done MvcSample.Bll for business logic, MvcSample.Data for data and MvcSample.Web for website.

In Data I've my edmx file (I'm using database first approach) and my repositories. And in Bll I'm doing services which will called in web.

So my question is that: Should I write other models in Bll or use that ones which are generated in edmx file?

*Should I write other models in Bll* That i assume you are talking about entity class and not model. — Divyang Desai, Oct 24 '16 at 06:19
you would face serialization issues (if you try to serialize any of the tables) with the references as some properties may be virtual and self referencing. Should be going with custom models. — Manoz, Oct 24 '16 at 06:22

score 1 · Answer 1 · answered Oct 24 '16 at 08:28

It heavily depends on the type of problem that your application is trying to solve.

From my experience, it is very rare that the business logic returns model objects directly from Entity Framework. Also, accepting these as arguments may not be the best idea.

Entity Framework model represents your relational database. Because of that, its definition contains many things that your business logic should not expose, for example navigation properties, computed properties etc. When accepting your model object as an argument, you may notice that many properties are not used by the particular business logic method. In many cases it confuses the developer and is the source of bugs.

All in all, if your application is a quick prototype, proof of concept or a simple CRUD software than it might be sufficient to use EF model classes. However, from practical point of view consider bespoke business logic model/dto classes.

score 0 · Answer 2 · answered Oct 24 '16 at 06:17

0

From my point of view you need another model for your Bll.

That would encapsulate your Bllcompletely.

answered Oct 24 '16 at 06:17

Daniel

9,491
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score 0 · Answer 3 · answered Oct 24 '16 at 06:22

I think there is no right or wrong answer for your question.

In my experience, I used both. Let's see at below example:

I have an User table

 public class User
 {
     public int Id{get;set;}
     public string First_Name{get;set;}
     public string Last_Name{get;set;}
     public int Age{get;set;}
     public string Password{get;set;} //let's use this for demonstration 
 }

I have a Method call DisplayAll() in Bll. This method should list down all users in my database by Full Names (FirstName + LastName) and their Ages. I should not return User class because it will expose the Password, but rather, I create a new Class UserDto

public class UserDto
{
    public string FullName{get;set;}
    public int Age{get;set;}
}

So here is my DisplayAll():

public List<UserDto> DisplayAll()
{
    List<UserDto> result = ctx.User  //my DbContext
                  .Select(x => new UserDto()
                  {
                  FullName = x.First_Name + " " +Last_Name,
                  Age = x.Age
                  }
    return result;
}

So as you can see, my method DisplayAll() uses both User and UserDto

score 0 · Answer 4 · answered Oct 24 '16 at 06:25

0

My approach will be

MvcSample.Data
 -- Model Classes 
 -- EDMX attach to model
MvcSample.Bll
 -- Model Inheriting MvcSample.Data.Model
 -- Business Logic Class - Using MvcSample.Bll.Model
MvcSample.Web
 -- Controller using  MvcSample.Bll.Model

answered Oct 24 '16 at 06:25

Nishant Kumar Verma

424
7
18

score 0 · Answer 5 · answered Oct 24 '16 at 06:28

It depends on your view about software design and how you want to take advantage of it. by separating BLL model, you will have your freedom to put story specific validation and calculation. By using only DLL model, it is sometimes tough as it is going to take effect in DB.

score 0 · Answer 6 · answered Oct 24 '16 at 06:39

You can use 3 tier architecture in asp.net in this way

MvcSample.BLL - business logic layer
MvcSample.DAL - Data access layer
MvcSample.Domain - Domain layer
MvcSample.web - website

All your repository classes are including in .BLL layer.That means your logics are stored here. Usually .DAL is used for storing .edmx classes. .Domain is using for recreate database objects that are useful for server side.That means if you are passing a json object from client to server,Then that object should be create on the server side.So those classes can be implement in the .domain

Business logic layer needs its own models or not

6 Answers6