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# 10.0: Adding Message Entity

We're going to build a messaging system. We'll start by adding a `Message` entity that will act as a join entity similarly to our `Follow` entity.

## Add Message Entity

In your `.Data/Entities` folder, add a new class called `Message.cs`:

```csharp
public class Message
{
    public int Id { get; set; }
    public int SenderId { get; set; }
    public User Sender { get; set; }
    public int RecipientId { get; set; }
    public User Recipient { get; set; }
    public string Content { get; set; }
    public bool IsRead { get; set; }
    public DateTime? DateRead { get; set; }
    public DateTime DateSent { get; set; }
    public bool SenderDeleted { get; set; }
    public bool RecipientDeleted { get; set; }
}
```

We have the join properties - `SenderId`/`Sender` and `RecipientId`/`Recipient`. But, we're also collecting more information about the `Message` than we did with the `Follow`. `Content`, `IsRead`, `DateRead`, and `DateSent` are pretty self explanatory.

However, we have separate properties for `SenderDeleted` and `RecipientDeleted`. If one user deletes a message - we don't want to delete it for the other user as well. We'll only delete the message from the database if both users delete it.

## Updating User Entity

We'll add two collection navigation properties on our `User` entity: one for messages received and one for messages sent:

```csharp
public ICollection<Message> MessagesSent { get; set; }

public ICollection<Message> MessagesReceived { get; set; }
```

## Updating EFConnectContext

Next, we need to update our `DbContext`. We'll start by adding a `DbSet` property:

```csharp
public DbSet<Message> Messages { get; set; }
```

Next, we'll configure it in the `OnModelCreating()` method:

```csharp
builder.Entity<Message>()
    .HasOne(u => u.Sender)
    .WithMany(u => u.MessagesSent)
    .OnDelete(DeleteBehavior.Restrict);

builder.Entity<Message>()
    .HasOne(u => u.Recipient)
    .WithMany(u => u.MessagesReceived)
    .OnDelete(DeleteBehavior.Restrict);
```

## Run Migration and Update Database

In your terminal, navigate to the `.Data` project and run the following command to add a new migration:

```
dotnet ef migrations add MessageEntity -s "../EFConnect.API/EFConnect.API.csproj"
```

Take a look at the migration and make sure it looks right, then run the following command to update the database:

```
dotnet ef database update -s "../EFConnect.API/EFConnect.API.csproj"
```

Here's an updated database diagram:

![DatabaseDiagram3](/files/-LAU8u1CXTb5RbCkrJaM)


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