Param schema array type does does not work with items element

[techolga]

Apache Airflow version

2.9.1

If "Other Airflow 2 version" selected, which one?

No response

What happened?

When I try to add item validation to an array type in the schema of a Param object passed to a DAG, the UI does render a Code box instead of an Array box and does not validate the jsonschema properly.

What you think should happen instead?

It should render the same UI element as it does when there is no field "items" in the schema.

How to reproduce

@dag(
    schedule=None,
    params={
        "mail": Param(
            schema={
                "title": "Email addresses",
                "type": ["array", "null"],
                # The following causes the issue (even "items": {} is enough)
                "items": {
                    "type": "string",
                    "format": "idn-email",
                    "minLength": 5,
                    "maxLength": 255,
                },
            }
        ),
    },
)
def any_dag():
	...

Test validation in REPL:

import jsonschema
schema={
    "type": ["array", "null"],
    "items": {
        "type": "string",
        "format": "idn-email",
        "minLength": 5,
        "maxLength": 255,
    },
}
jsonschema.validate(['test@mail.com'], schema, format_checker=jsonschema.FormatChecker())
# does not raise an exception

jsonschema.validate(['testmail.com'], schema, format_checker=jsonschema.FormatChecker())
# does raise an exception

Operating System

Debian GNU/Linux 12 (bookworm)

Versions of Apache Airflow Providers

apache-airflow-providers-amazon==8.20.0
apache-airflow-providers-celery==3.6.2
apache-airflow-providers-cncf-kubernetes==8.1.1
apache-airflow-providers-common-io==1.3.1
apache-airflow-providers-common-sql==1.12.0
apache-airflow-providers-docker==3.10.0
apache-airflow-providers-elasticsearch==5.3.4
apache-airflow-providers-fab==1.0.4
apache-airflow-providers-ftp==3.8.0
apache-airflow-providers-google==10.17.0
apache-airflow-providers-grpc==3.4.1
apache-airflow-providers-hashicorp==3.6.4
apache-airflow-providers-http==4.10.1
apache-airflow-providers-imap==3.5.0
apache-airflow-providers-microsoft-azure==10.0.0
apache-airflow-providers-mysql==5.5.4
apache-airflow-providers-odbc==4.5.0
apache-airflow-providers-openlineage==1.7.0
apache-airflow-providers-postgres==5.10.2
apache-airflow-providers-redis==3.6.1
apache-airflow-providers-sendgrid==3.4.0
apache-airflow-providers-sftp==4.9.1
apache-airflow-providers-slack==8.6.2
apache-airflow-providers-smtp==1.6.1
apache-airflow-providers-snowflake==5.4.0
apache-airflow-providers-sqlite==3.7.1
apache-airflow-providers-ssh==3.10.1

Deployment

Docker-Compose

Deployment details

No response

Anything else?

No response

Are you willing to submit PR?

• Yes I am willing to submit a PR!

Code of Conduct

• I agree to follow this project's Code of Conduct

[boring-cyborg]

Thanks for opening your first issue here! Be sure to follow the issue template! If you are willing to raise PR to address this issue please do so, no need to wait for approval.

[RNHTTR]

Once this is resolved, there should probably be a doc page on using the schema parameter for a Param.

[techolga]

Totally agree, the docs do not describe the default behavior and the schema parameter for Param.

With #39993 at least the default behavior for string arrays is switched to present the standard array textarea which should be consistent with the docs and examples