feat: Allow deferred data_source initialization by cpsievert · Pull Request #202 · posit-dev/querychat

cpsievert · 2026-01-23T16:57:53Z

Summary

Allow data_source to be None at QueryChat initialization, deferring binding until server() is called
Add settable data_source property that rebuilds system prompt when changed
Add data_source parameter to Shiny server() method for the deferred pattern
Update all framework implementations (Shiny, Streamlit, Gradio, Dash) to support None data_source

Motivation

This enables Shiny Core applications where:

UI is defined in "global" scope
Database connections need to be created per-user in server scope
Credentials may depend on session-specific authentication

# Global scope - UI created before data source
qc = QueryChat(None, "users")

def app_ui(request):
    return ui.page_sidebar(qc.sidebar(), ...)

def server(input, output, session):
    # Data source provided in server scope
    qc_vals = qc.server(data_source=get_connection(session))

Test plan

Added unit tests for deferred initialization pattern
Added integration tests for full workflow
Verified backward compatibility with existing tests
All 247 tests pass

🤖 Generated with Claude Code

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Stores table_name and init parameters for deferred system prompt building. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Normalizes the data source and rebuilds system prompt when set. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Methods that need data_source now raise RuntimeError with helpful message. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Allows deferred data source pattern where UI is created before data source is available (e.g., in Shiny Core global scope). Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

QueryChatExpress requires data_source at init since it calls mod_server. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

These frameworks require data_source before app()/ui() since there's no separate server() call like in Shiny. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

- Add ibis.Table to server() data_source type hint - Remove unnecessary comments in server() method - Make QueryChatExpress data_source required (not optional) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Add assert statements after _require_data_source() calls to help pyright narrow types from DataSource | None to DataSource. Also capture local variables for nested functions where type narrowing doesn't carry through. feat(pkg-r): implement deferred data source pattern Allow data_source to be NULL at initialization, deferring the actual data source binding until $server() is called. This enables Shiny Core apps where UI is in global scope but database connections need to be created per-user in server scope. Changes: - data_source parameter accepts NULL in initialize() - $data_source property is now settable - $server() accepts optional data_source parameter - Added _require_data_source checks to methods that need data - Updated CHANGELOG.md and NEWS.md Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Document the deferred data source pattern for per-user database connections in Shiny Core applications. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Update _data_source type annotation to DataSource | None to match QueryChatBase. Add assertions to methods that use _data_source. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Assert statements are used for type narrowing after _require_data_source() which already handles runtime validation. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

…pe narrowing Replace assert statements with `# noqa: S101` by having `_require_data_source()` return the validated DataSource. This provides cleaner type narrowing without needing to suppress lint warnings. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

- Add `data_source: None` overload to QueryChatExpress - Use class variable to cache bookmarking settings between stub and real sessions - Defer mod_server() call to real session (skip during stub session) - Add _require_vals() helper for safe accessor access - Update documentation for Express deferred pattern Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

- Update mod_server() to accept data_source: DataSource | None - Handle None data_source during stub session (return placeholder ServerValues) - Raise clear error if data_source is None during real session - Simplify QueryChatExpress to always call mod_server() with self._data_source - Remove _require_vals() helper, use self._vals directly Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

cpsievert and others added 9 commits January 23, 2026 10:37

test: add failing tests for deferred data source initialization

aeb7f38

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

feat: allow None data_source in QueryChatBase.__init__

67140ef

Stores table_name and init parameters for deferred system prompt building. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

feat: add settable data_source property

2a0041a

Normalizes the data source and rebuilds system prompt when set. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

feat: add data_source requirement checks to methods

286f98d

Methods that need data_source now raise RuntimeError with helpful message. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

feat(shiny): add data_source parameter to server() method

fada69d

Allows deferred data source pattern where UI is created before data source is available (e.g., in Shiny Core global scope). Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

feat(shiny): update QueryChatExpress for None data_source handling

f660386

QueryChatExpress requires data_source at init since it calls mod_server. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

feat: update Streamlit/Gradio/Dash for None data_source

605fc24

These frameworks require data_source before app()/ui() since there's no separate server() call like in Shiny. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

test: add integration tests for deferred pattern

456653c

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

style: apply ruff formatting

f97e3bc

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

cpsievert temporarily deployed to pypi January 23, 2026 16:57 — with GitHub Actions Inactive

cpsievert commented Jan 23, 2026

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cpsievert commented Jan 23, 2026

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cpsievert commented Jan 23, 2026

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cpsievert commented Jan 23, 2026

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Comment thread pkg-py/src/querychat/_shiny.py

fix: address PR feedback

c53ced5

- Add ibis.Table to server() data_source type hint - Remove unnecessary comments in server() method - Make QueryChatExpress data_source required (not optional) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

cpsievert temporarily deployed to pypi January 23, 2026 17:08 — with GitHub Actions Inactive

cpsievert temporarily deployed to pypi January 23, 2026 17:16 — with GitHub Actions Inactive

air format (GitHub Actions)

e48da20

cpsievert changed the title ~~feat(pkg-py): Allow deferred data_source initialization~~ feat: Allow deferred data_source initialization Jan 23, 2026

cpsievert commented Jan 23, 2026

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Comment thread pkg-r/NEWS.md Outdated

Update pkg-r/NEWS.md

a0694d2

cpsievert temporarily deployed to pypi January 23, 2026 17:31 — with GitHub Actions Inactive

docs: add deferred data source documentation

9e1fd82

Document the deferred data source pattern for per-user database connections in Shiny Core applications. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

cpsievert temporarily deployed to pypi January 23, 2026 17:35 — with GitHub Actions Inactive

fix(pkg-py): fix type incompatibility in StateDictAccessorMixin

7b35d2f

Update _data_source type annotation to DataSource | None to match QueryChatBase. Add assertions to methods that use _data_source. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

cpsievert temporarily deployed to pypi January 23, 2026 17:37 — with GitHub Actions Inactive

fix(pkg-py): add noqa comments for S101 lint rule

67352d2

Assert statements are used for type narrowing after _require_data_source() which already handles runtime validation. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

cpsievert temporarily deployed to pypi January 23, 2026 17:40 — with GitHub Actions Inactive

cpsievert had a problem deploying to pypi January 23, 2026 20:04 — with GitHub Actions Failure

cpsievert temporarily deployed to pypi January 23, 2026 20:42 — with GitHub Actions Inactive

cpsievert temporarily deployed to pypi January 23, 2026 20:58 — with GitHub Actions Inactive

Mock 'real' session behavior

3050d5a

cpsievert temporarily deployed to pypi January 23, 2026 21:06 — with GitHub Actions Inactive

Cleanup R article

683e66d

cpsievert temporarily deployed to pypi January 23, 2026 21:11 — with GitHub Actions Inactive

cpsievert requested a review from Copilot January 23, 2026 22:45

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cpsievert commented Jan 23, 2026

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Comment thread pkg-py/docs/build.qmd Outdated

Cleanup Express example docs

4c8a65b

cpsievert temporarily deployed to pypi January 23, 2026 23:02 — with GitHub Actions Inactive

cpsievert merged commit 27c4cc5 into main Jan 23, 2026
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cpsievert deleted the deferred-datasource branch January 23, 2026 23:03

github-actions Bot restored the deferred-datasource branch January 23, 2026 23:07

cpsievert mentioned this pull request Feb 9, 2026

Better support for reactive data sources #184

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feat: Allow deferred data_source initialization#202

feat: Allow deferred data_source initialization#202
cpsievert merged 22 commits intomainfrom
deferred-datasource

cpsievert commented Jan 23, 2026

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cpsievert commented Jan 23, 2026

Summary

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Test plan

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