Relational DB - Getting Data including Data from Other Entities (Repository Pattern)

Let's see how we can get data from a primary entity that has reference to other entities

Implementation

Creating an Application

How to create .NET web-API

Adding Relationship

Adding Relation to DB

For better demonstration, I have created three entities

You can download the seed data for testing

item.json

0.00MB

itemTarget.json

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itemType.json

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Adding Repository Pattern

Application Architecture - Repository with Service

Adding Methods in the Interface

Add methods to the interface to get data from each entity

Implementing Interface

Go to the repository and implement the methods

Updating the Controller

Add additional endpoints for added entities. To specify the path use parenthesis and put a path in it as a string

[HttpGet("targets")]

 

Run

Move to the API folder

cd /API

And run the app

dotnet watch

You will see added endpoints right away like below if you are using Swagger

Open each and try

Getting Referenced Data from the Primary Entity

As you can see, referenced data in the primary entity show a 'null' value. We need an additional step to show their data

 

Add EntityFrameworCore namespace in the repository file

using Microsoft.EntityFrameworkCore;

Then add the 'Include' method to include data from foreign entities

public List<Item> GetItems()
{
  return _context.Items
  .Include(i => i.ItemTarget)
  .Include(i => i.ItemType)
  .ToList();
}

After the update, you will see that the actual data comes back not the null values

We have seen how we can get data from an entity that has reference to other entities.