Support multiline input for Params of type string in trigger UI form (#…

…40414)

* Add multiline input (textarea) support for Params of type string in trigger UI form

* Use the 'format' attribute in the Param for rendering a multiline text area in the trigger UI form

* Update example DAG and documentation to illustrate the use of a multiline text Param

airflow/example_dags/example_params_ui_tutorial.py

@@ -165,6 +165,12 @@
             title="Time Picker",
             description="Please select a time, use the button on the left for a pop-up tool.",
         ),
+        "multiline_text": Param(
+            "A multiline text Param\nthat will keep the newline\ncharacters in its value.",
+            description="This field allows for multiline text input. The returned value will be a single with newline (\\n) characters kept intact.",
+            type=["string", "null"],
+            format="multiline",
+        ),
         # Fields can be required or not. If the defined fields are typed they are getting required by default
         # (else they would not pass JSON schema validation) - to make typed fields optional you must
         # permit the optional "null" type.

airflow/www/templates/airflow/trigger.html

@@ -127,6 +127,12 @@
         {%- if form_details.schema.minimum %} min="{{ form_details.schema.minimum }}"{% endif %}
         {%- if form_details.schema.maximum %} max="{{ form_details.schema.maximum }}"{% endif %}
         {%- if form_details.schema.type and not "null" in form_details.schema.type %} required=""{% endif %} />
+    {% elif form_details.schema and "string" in form_details.schema.type and "format" in form_details.schema and form_details.schema.format == "multiline" %}
+      <textarea class="form-control" name="element_{{ form_key }}" id="element_{{ form_key }}" rows="6"
+        {%- if not "null" in form_details.schema.type %} required=""{% endif -%}
+        {%- if form_details.schema and form_details.schema.minLength %} minlength="{{ form_details.schema.minLength }}"{% endif %}
+        {%- if form_details.schema and form_details.schema.maxLength %} maxlength="{{ form_details.schema.maxLength }}"{% endif %}
+      >{% if form_details.value %}{{- form_details.value -}}{% endif %}</textarea>
     {% else %}
       <input class="form-control" name="element_{{ form_key }}" id="element_{{ form_key }}"
         type="{% if "examples" in form_details.schema and form_details.schema.examples %}search{% else %}text{% endif %}"

docs/apache-airflow/core-concepts/params.rst

@@ -232,14 +232,15 @@ The following features are supported in the Trigger UI Form:
           - Example
 
         * - ``string``
-          - Generates a single-line text box to edit text.
+          - Generates a single-line text box or a text area to edit text.
           - * ``minLength``: Minimum text length
             * ``maxLength``: Maximum text length
             * | ``format="date"``: Generate a date-picker
               | with calendar pop-up
             * | ``format="date-time"``: Generate a date and
               | time-picker with calendar pop-up
             * ``format="time"``: Generate a time-picker
+            * ``format="multiline"``: Generate a multi-line textarea
             * | ``enum=["a", "b", "c"]``: Generates a
               | drop-down select list for scalar values.
               | As of JSON validation, a value must be