FQLv10 and creation of databases

Help
1

Hello,

I’m running into an issue when trying to migrate some test fixtures from FQLv4 to FQLv10. I have an existing FQLv4 pytest fixture that generates test databases to run tests against:

@pytest.fixture
def test_db(fauna_admin_client):
    """Create a randomly named test child database for use in this test module and
    return its name.

    This will delete the test database after the session completes.
    """
    # Create the test database
    test_db_name = f"test-fluctuate-{uuid4()}"
    result = fauna_admin_client.query(query.create_database({"name": test_db_name}))

    # Yield the test database.
    yield result

    # Use a top level admin key to delete the child database.
    fauna_admin_client.query(query.delete(result["ref"]))

I converted it to FQLv10 like so:

@pytest.fixture
def test_db(fauna_admin_client):
    """Create a randomly named test child database for use in this test module and
    return its name.

    This will delete the test database after the session completes.
    """
    # Create the test database
    test_db_name = f"test-fluctuate-{uuid4()}"
    result = fauna_admin_client.query(
        fql("Database.create({name: ${test_db_name}})", test_db_name=test_db_name)
    )

    # Yield the test database.
    yield result.data

    # Use a top level admin key to delete the child database.
    fauna_admin_client.query(
        fql("Database.byName(${test_db_name}).delete()", test_db_name=test_db_name)
    )

The FQLv4 version works fine. However, when I run the FQLv10 version, I get the following error:

E                   fauna.errors.errors.QueryRuntimeError: 400: constraint_failure
E                   Failed to create document in collection Database.
E                   ---
E                   constraint failures: [ConstraintFailure(message='Invalid identifier.', name=None, paths=[['name']])]
E                   ---
E                   error: Failed to create document in collection Database.
E                   constraint failures:
E                     name: Invalid identifier.
E                   at *query*:1:16
E                     |
E                   1 | Database.create({name: <value>})
E                     |                ^^^^^^^^^^^^^^^^^
E                     |

The name it was trying to use in this case was test-fluctuate-bca9ec33-9c58-493b-9616-442655a647c6. Are there new limitations on DB names in FQLv10? There are no docs on the Database collection yet that I can find to confirm one way or the other.

2

Resources in FQL 10 are referenced directly by their name, so their names must be valid identifiers.

Your DB name is not a valid identifier, because it contains hyphens.

I agree that we need to improve documentation in this area. We talk about identifiers, but I don’t see that we require Database names to be valid identifiers. Thanks for bringing this to our attention! I have filed an internal ticket to review this.

3

@ptpaterson why are hyphens not allowed?

4

For example, when you create a Collection named “User”, future queries have the identifier User added to the global scope.

create a collection

Collection.create({ name: "User" })

User is not available in the global scope

User.create({ /*...*/ })

Not all schema are available in the global scope, for example Roles and child Databases are not, but the naming convention is still applied consistently across schema.

5

@ptpaterson thanks, but I’m not sure that answers my question: What’s the technical limitation as to why a - is not allowed, but a _ is, at least according to the identifier docs? From the outside looking in, it doesn’t seem much different to say foo-bar instead of foo_bar.

6

Why are hyphens not allowed in identifiers of other languages, but underscores are? FQL is code, and hyphens in code mean subtraction.

If you named a Collection “foo-bar” that suggests you would use that collection like

foo-bar.create({...})

But that won’t do what you want it to do. It will look for an identifier foo and try to perform subtraction with the result of bar.create({...})

To avoid this issue, schema names must be valid identifiers.

Note that Collection.byName("Foo") does not return the same type as Foo. Foo is a “companion” object that gives you the functions like .create. Collection.byName("Foo") is actually the definition document for the Collection. This means that you cannot do something like

// Invalid FQL
Collection.byName("Foo").create({
  title: "my foo document"
})

error: The function `create` does not exist on `Doc`
at *query*:1:28
  |
1 | Collection.byName("Foo").create({
  |                          ^^^^^^
7

Ah, I had incorrectly assumed whitespace would be necessary in order to distinguish subtraction from a name. Thanks for the details.

8

No problem! Thanks for the excellent questions and feedback. :smile:

9

This topic was automatically closed 2 days after the last reply. New replies are no longer allowed.