4. What about bidirectional queries?

In Dataloom, we support bidirectional relations with eager loading on-the-fly. You can query from a parent to a child and from a child to a parent. You just need to know how the relationship is mapped between these two models. In this case, the has option is very important in the Include class. Here are some examples demonstrating bidirectional querying between user and post, where the user is the parent table and the post is the child table in this case.

1. Child to Parent

Here is an example illustrating how we can query a parent from child table.

posts_users = mysql_loom.find_many(
    Post,
    limit=2,
    offset=3,
    order=[Order(column="id", order="DESC")],
    select=["id", "title"],
    include=[
        Include(
            model=User,
            select=["id", "username"],
            has="one",
            include=[Include(model=Profile, select=["id", "avatar"], has="one")],
        ),
        Include(
            model=Category,
            select=["id", "type"],
            order=[Order(column="id", order="DESC")],
            has="many",
            limit=2,
        ),
    ],
)
print(posts_users) # ? = [{'id': 1, 'title': 'Hey', 'user': {'id': 1, 'username': '@miller', 'profile': {'id': 1, 'avatar': 'hello.jpg'}}, 'categories': [{'id': 4, 'type': 'sport'}, {'id': 3, 'type': 'tech'}]}]

2. Parent to Child

Here is an example of how we can query a child table from parent table

user_post = mysql_loom.find_by_pk(
    User,
    pk=userId,
    select=["id", "username"],
    include=[
        Include(
            model=Post,
            limit=2,
            offset=3,
            order=[Order(column="id", order="DESC")],
            select=["id", "title"],
            include=[
                Include(
                    model=User,
                    select=["id", "username"],
                    has="one",
                    include=[
                        Include(model=Profile, select=["id", "avatar"], has="one")
                    ],
                ),
                Include(
                    model=Category,
                    select=["id", "type"],
                    order=[Order(column="id", order="DESC")],
                    has="many",
                    limit=2,
                ),
            ],
        ),
        Include(model=Profile, select=["id", "avatar"], has="one"),
    ],
)


print(user_post) """ ? =
{'id': 1, 'username': '@miller', 'user': {'id': 1, 'username': '@miller', 'profile': {'id': 1, 'avatar': 'hello.jpg'}}, 'categories': [{'id': 4, 'type': 'sport'}, {'id': 3, 'type': 'tech'}], 'posts': [{'id': 1, 'title': 'Hey', 'user': {'id': 1, 'username': '@miller', 'profile': {'id': 1, 'avatar': 'hello.jpg'}}, 'categories': [{'id': 4, 'type': 'sport'}, {'id': 3, 'type': 'tech'}]}], 'profile': {'id': 1, 'avatar': 'hello.jpg'}}
"""