To configure the connection to MongoDB, call the following function in your Startup.cs

services.AddMongoDBConnection();

It is possible to supply this function with a MongoOptions object specifying the connection string and database name to be used. If this object is not given the connection string and database name will be taken from the environment values CONNECTIONSTRING and DATABASE_NAME, respectively (This is for backward compatibility reasons).

To use a collection for a certain type in your application, add the following line to your Startup.cs:

services.UseMongoDBCollection<T>();

Where T must implement IMongoModel. You can then use an IMongoCollection<T> as a dependency in your repository.

It is possible to retrieve a IMongoQueryable<T> by running

IMongoCollection<T> collection ...
IMongoQueryable<T> queryable = collection.AsQueryable();

This object allows you to retrieve objects from the database using Linq methods. For example:

async Task<T> GetById(Guid id)
{
  return await queryable.SingleOrDefaultAsync(t => t.Id == id);
}

A situation that often comes up when writing your repository is where you need to update or delete an existing object based on its id. The MongoCollection methods require you to specify a filter for this. A pre-made filter for finding an object based on its Id attribute can be retrieved by using the MongoUtilities.IdFilter<T>() function. Some examples:

void Update(T obj)
{
  var idFilter = MongoUtilities.IdFilter(T obj);
  mongoCollection.ReplaceOne(idFilter, obj);
}

void Delete(Guid id)
{
  var idFilter = MongoUtilities.IdFilter<T>(id);
  mongoCollection.DeleteOne(idFilter);
}

Where T must implement IMongoModel.

If you want to return an IMongoQueryable<T> as a paginated object it is possible to use the AsPaginatedResponse<T> function:

var filteredQuery = queryable.Where(t => ...);
PaginatedResponse<T> response = await filteredQuery.AsPaginatedResponse(limit, offset);

This will do a call to the database to retrieve the data (based on the limit and offset) and a total count.