Conditional questions

Conditional questions#

In this tutorial you will build a form that shows extra questions only when a previous answer matches a specific value.

This is useful for branching forms where some options require additional configuration—for example, enabling a feature and then asking for its settings.

What you will build#

A deployment configuration form that:

  1. Asks which authentication provider to use (none or oidc).

  2. Shows two extra questions—OIDC server URL and client ID—only when the user selects oidc.

Prerequisites#

How conditional questions work#

TUI Forms uses the standard JSONSchema allOf / if / then pattern.

"allOf": [
  {
    "if":   { "properties": { "key": { "const": "expected_value" } } },
    "then": { "properties": { "extra_field": { <question schema> } } }
  }
]

When the user's answer for key equals expected_value, the questions inside then.properties become active. Otherwise they are skipped entirely—they will not appear in the returned answers dict.

The if condition must follow the pattern {properties: {key: {const: value}}}. Only a single key–value pair per if block is supported.

Step 1—Define the base question#

Start with the choice question that controls the branching:

schema = {
    "title": "Deployment configuration",
    "properties": {
        "auth_provider": {
            "type": "string",
            "title": "Authentication provider",
            "default": "none",
            "oneOf": [
                {"const": "none", "title": "None"},
                {"const": "oidc", "title": "OpenID Connect (OIDC)"},
            ],
        },
    },
}

Step 2—Add the conditional block#

Append an allOf list at the top level of the schema (alongside properties). Each item has an if condition and a then block with the extra questions:

schema = {
    "title": "Deployment configuration",
    "properties": {
        "auth_provider": {
            "type": "string",
            "title": "Authentication provider",
            "default": "none",
            "oneOf": [
                {"const": "none", "title": "None"},
                {"const": "oidc", "title": "OpenID Connect (OIDC)"},
            ],
        },
    },
    "allOf": [
        {
            "if": {
                "properties": {"auth_provider": {"const": "oidc"}}
            },
            "then": {
                "properties": {
                    "oidc_server_url": {
                        "type": "string",
                        "title": "OIDC server URL",
                        "description": "for example, https://auth.example.com/realms/myrealm",
                        "default": "",
                    },
                    "oidc_client_id": {
                        "type": "string",
                        "title": "Client ID",
                        "default": "my-app",
                    },
                }
            },
        }
    ],
}

Step 3—Run the form#

from tui_forms import create_renderer

renderer = create_renderer("stdlib", schema)
answers = renderer.render()
print(answers)

Step 4—Try both branches#

Run the script and select None first:

{'auth_provider': 'none'}

The OIDC questions are skipped; they do not appear in the answers at all.

Run again and select OpenID Connect (OIDC):

{'auth_provider': 'oidc', 'oidc_server_url': 'https://auth.example.com/realms/myrealm', 'oidc_client_id': 'my-app'}

This time both extra questions were asked and their answers are in the dict.

Multiple conditional branches#

You can add more allOf items to handle additional choices. Each item is evaluated independently:

"allOf": [
    {
        "if": {"properties": {"auth_provider": {"const": "oidc"}}},
        "then": {
            "properties": {
                "oidc_server_url": {"type": "string", "title": "OIDC server URL"},
                "oidc_client_id":  {"type": "string", "title": "Client ID"},
            }
        },
    },
    {
        "if": {"properties": {"auth_provider": {"const": "saml"}}},
        "then": {
            "properties": {
                "saml_metadata_url": {"type": "string", "title": "SAML metadata URL"},
            }
        },
    },
]

Next steps#

Contents