a0a08cc398
When a flow is uploaded via API and run via API, global variables with
"Apply to Fields" (default_fields) were silently ignored. The component
received an empty value and failed with errors like
"OpenAI API key is required". Opening the flow once in the Playground
worked around it because the frontend writes load_from_db: true back to
the stored template.
Root cause: variable resolution at vertex build time
(update_params_with_load_from_db_fields) only fires for fields whose
stored template already has load_from_db: true. That flag is set
exclusively by the frontend's inputGlobalComponent hook, which
API-only workflows never trigger.
Fix: mirror the frontend's behaviour in-memory inside simple_run_flow,
just before Graph.from_payload. A new helper module
langflow.api.v1.global_variable_defaults builds the same
{display_name: variable_name} map as getUnavailableFields and applies
it to empty, eligible (str-type, visible, not already load_from_db)
template fields. The mutation is local to the request; the stored
flow is unchanged. Variable-service errors are logged and swallowed so
a lookup failure cannot block flow execution.
Tests: 27 unit tests cover map construction, the pure graph
transformer (matching rules, skip rules, immutability, malformed
input tolerance), and the async wrapper (success and failure paths).
Fixes #11781
Langflow is a powerful platform for building and deploying AI-powered agents and workflows. It provides developers with both a visual authoring experience and built-in API and MCP servers that turn every workflow into a tool that can be integrated into applications built on any framework or stack. Langflow comes with batteries included and supports all major LLMs, vector databases and a growing library of AI tools.
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