feat(blocks): add min_lines/max_lines to RichTextInputElement

[srtaalej]

Summary

Adds optional min_lines and max_lines integer properties to the RichTextInputElement Block Kit model, allowing developers to control the visible height of rich_text_input elements.

• min_lines — minimum number of visible lines (1–100)
• max_lines — maximum number of visible lines before scrolling (1–100, defaults to 8 on the platform when unset)

Both properties are optional, preserving full backward compatibility.

Testing

./scripts/run_tests.sh tests/slack_sdk/models/test_elements.py

New test methods: test_min_lines, test_max_lines, test_min_and_max_lines — all verify round-trip serialization.

Test app.py

import os
import logging

from slack_bolt import App
from slack_bolt.adapter.socket_mode import SocketModeHandler

logging.basicConfig(level=logging.DEBUG)

app = App(token=os.environ.get("SLACK_BOT_TOKEN"))


@app.command("/sample-command")
def open_rich_text_modal(ack, client, body):
    ack()
    client.views_open(
        trigger_id=body["trigger_id"],
        view={
            "type": "modal",
            "title": {"type": "plain_text", "text": "Rich Text Test"},
            "submit": {"type": "plain_text", "text": "Submit"},
            "blocks": [
                {
                    "type": "input",
                    "block_id": "rich_text_block",
                    "label": {"type": "plain_text", "text": "Default (no min/max — should be 8 max)"},
                    "element": {
                        "type": "rich_text_input",
                        "action_id": "default_input",
                    },
                },
                {
                    "type": "input",
                    "block_id": "rich_text_min_block",
                    "label": {"type": "plain_text", "text": "min_lines: 5"},
                    "element": {
                        "type": "rich_text_input",
                        "action_id": "min_input",
                        "min_lines": 5,
                    },
                },
                {
                    "type": "input",
                    "block_id": "rich_text_max_block",
                    "label": {"type": "plain_text", "text": "max_lines: 16"},
                    "element": {
                        "type": "rich_text_input",
                        "action_id": "max_input",
                        "max_lines": 16,
                    },
                },
                {
                    "type": "input",
                    "block_id": "rich_text_both_block",
                    "label": {"type": "plain_text", "text": "min_lines: 3, max_lines: 20"},
                    "element": {
                        "type": "rich_text_input",
                        "action_id": "both_input",
                        "min_lines": 3,
                        "max_lines": 20,
                    },
                },
            ],
        },
    )


if __name__ == "__main__":
    SocketModeHandler(app, os.environ.get("SLACK_APP_TOKEN")).start()

Category

• slack_sdk.models (UI component builders)
• tests/integration_tests (Automated tests for this library)

Requirements

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.
• I've run python3 -m venv .venv && source .venv/bin/activate && ./scripts/run_validation.sh after making the changes.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.17%. Comparing base (176b6cb) to head (994f30b).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1925      +/-   ##
==========================================
+ Coverage   84.14%   84.17%   +0.03%     
==========================================
  Files         118      118              
  Lines       13423    13425       +2     
==========================================
+ Hits        11295    11301       +6     
+ Misses       2128     2124       -4     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

[zimeg]

🙏 Awesome to find these options supported as expected arguments! LGTM!