Abp Mongodb

Repository Implementation

public class BookRepository : MongoDbRepository<MyProjectMongoDbContext, Book, Guid>, IBookRepository
{
    public BookRepository(IMongoDbContextProvider<MyProjectMongoDbContext> dbContextProvider)
        : base(dbContextProvider)
    {
    }

    public async Task<Book> FindByNameAsync(
        string name,
        bool includeDetails = true,
        CancellationToken cancellationToken = default)
    {
        return await (await GetQueryableAsync())
            .FirstOrDefaultAsync(
                b => b.Name == name,
                GetCancellationToken(cancellationToken));
    }

    public async Task<List<Book>> GetListByAuthorAsync(
        Guid authorId,
        bool includeDetails = false,
        CancellationToken cancellationToken = default)
    {
        return await (await GetQueryableAsync())
            .Where(b => b.AuthorId == authorId)
            .ToListAsync(GetCancellationToken(cancellationToken));
    }
}

Module Configuration

[DependsOn(typeof(AbpMongoDbModule))]
public class MyProjectMongoDbModule : AbpModule
{
    public override void ConfigureServices(ServiceConfigurationContext context)
    {
        context.Services.AddMongoDbContext<MyProjectMongoDbContext>(options =>
        {
            // Add default repositories for aggregate roots only (DDD best practice)
            options.AddDefaultRepositories();
            // ⚠️ Avoid includeAllEntities: true - breaks DDD data consistency
        });
    }
}

Connection String

In appsettings.json:

{
  "ConnectionStrings": {
    "Default": "mongodb://localhost:27017/MyProjectDb"
  }
}

Key Differences from EF Core

No Migrations

MongoDB is schema-less; no migrations needed. Changes to entity structure are handled automatically.

includeDetails Parameter

Often ignored in MongoDB because documents typically embed related data:

public async Task<List<Book>> GetListAsync(
    bool includeDetails = false, // Usually ignored
    CancellationToken cancellationToken = default)
{
    // MongoDB documents already include nested data
    return await (await GetQueryableAsync())
        .ToListAsync(GetCancellationToken(cancellationToken));
}

Embedded Documents vs References

// Embedded (stored in same document)
public class Order : AggregateRoot<Guid>
{
    public List<OrderLine> Lines { get; set; } // Embedded
}

// Reference (separate collection, store ID only)
public class Order : AggregateRoot<Guid>
{
    public Guid CustomerId { get; set; } // Reference by ID
}

No Change Tracking

MongoDB doesn't track entity changes automatically:

public async Task UpdateBookAsync(Guid id, string newName)
{
    var book = await _bookRepository.GetAsync(id);
    book.SetName(newName);

    // Must explicitly update
    await _bookRepository.UpdateAsync(book);
}

Direct Collection Access

public async Task CustomOperationAsync()
{
    var collection = await GetCollectionAsync();

    // Use MongoDB driver directly
    var filter = Builders<Book>.Filter.Eq(b => b.AuthorId, authorId);
    var update = Builders<Book>.Update.Set(b => b.IsPublished, true);

    await collection.UpdateManyAsync(filter, update);
}

Indexing

Configure indexes in repository or via MongoDB driver:

public class BookRepository : MongoDbRepository<MyProjectMongoDbContext, Book, Guid>, IBookRepository
{
    public override async Task<IQueryable<Book>> GetQueryableAsync()
    {
        var collection = await GetCollectionAsync();

        // Ensure index exists
        var indexKeys = Builders<Book>.IndexKeys.Ascending(b => b.Name);
        await collection.Indexes.CreateOneAsync(new CreateIndexModel<Book>(indexKeys));

        return await base.GetQueryableAsync();
    }
}

Best Practices

• Design documents for query patterns (denormalize when needed)
• Use references for frequently changing data
• Use embedding for data that's always accessed together
• Add indexes for frequently queried fields
• Use GetCancellationToken(cancellationToken) for proper cancellation
• Remember: ABP data filters (soft-delete, multi-tenancy) work with MongoDB too