The Differences Between EntityFramework .Add and .AddAsync

#csharp #softwaredevelopment #entityframework

Introduction

Entity Framework is a popular Object-Relational Mapper (ORM) for .NET, which allow us to better interact with a database using .NET objects. One of the fundamental operations we are using all of us that interact with databases is adding new entities. In this article I will try to explain the two methods that we have in our disposal for entities creation Add and AddAsync. We will explore their usage, differences and best practices for when to use each other.

What is `DbSet<TEntity>.Add`?

The DbSet.Add method is a synchronous method used to add a new entity to the context, which is then tracked by EF Core. When SaveChanges is called, EF Core generates the necessary SQL statements to insert the new entity into the database.
Lets see a usage example of Add method

public Task AddNewEntityAsync(Entity entity, CancellationToken ct)
{
    using (var context = new ApplicationDbContext())
    {
        context.Entities.Add(entity);
        await context.SaveChangesAsync(ct);
    }
}

How the above example works,

The Add method attaches the entity to the context with an Added state
When SaveChangesAsync is called the context creates an INSERT SQL command to add the entity to the database asynchronously

What is `DbSet<TEntity>.AddAsync`?

The AddAsync method is the asynchronous counterpart of the Add method. It is used to add a new entity to the context asynchronously. A usage example of AddAsync is given bellow

public async Task AddAsync(Entity entity)
{
    using (var context = new ApplicationDbContext())
    {
        await context.Entities.AddAsync(entity);
        await context.SaveChangesAsync();
    }
}

How it works
The AddAsync method attaches the entity to the context with an Added state asynchronously

When SaveChangesAsync is called, the context creates an INSERT SQL command to add the entity to the database asynchronously

Key Differences Between `Add` and `AddAsync`

Now the first question that pops in our minds is ok, so I will use Add when I am in a synchronous context and AddAsync when I am in asynchronous.
This is just one aspect; the other is how Add and AddAsync interact with the database.
As Microsoft explains

This method is async only to allow special value generators, such as the one used by 'Microsoft.EntityFrameworkCore.Metadata.SqlServerValueGenerationStrategy.SequenceHiLo', to access the database asynchronously. For all other cases the non async method should be used.

That simple means that event though Add and AddAsync are doing the same thing, AddAsync comes with a little overhead and that is an extra interaction with the database, something that is avoided with the use of Add

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