dify/api/controllers/API_SCHEMA_GUIDE.md

API Schema Guide

This guide describes the expected Flask-RESTX + Pydantic pattern for controller request payloads, query parameters, response schemas, and Swagger documentation.

Principles

• Use Pydantic BaseModel for request bodies and query parameters.
• Use fields.base.ResponseModel for response DTOs.
• Keep runtime validation and Swagger documentation wired to the same Pydantic model.
• Prefer explicit validation and serialization in controller methods over Flask-RESTX marshalling.
• Do not add new Flask-RESTX fields.* dictionaries, Namespace.model(...) exports, or @marshal_with(...) for migrated or new endpoints.
• Do not use @ns.expect(...) for GET query parameters. Flask-RESTX documents that as a request body.

Public System Features Contract

The Console and Web /system-features endpoints share SystemFeatureModel. They are unauthenticated and may be requested during root SSR, so treat this response as a minimal public bootstrap allowlist. It is not a general configuration endpoint, a feature registry, or a mirror of environment and Enterprise settings. Existing fields are legacy inventory and do not establish precedent for new fields.

A new field is eligible only when all of the following are true:

1. Both Console and Web have named production consumers for the field.
2. Both consumers need the value before authentication and tenant/workspace bootstrap to render initial state or choose an authentication flow.
3. The value varies at runtime or by deployment and cannot be safely derived from an existing public contract.
4. The value is non-sensitive, safe to disclose without authentication, and has stable public API semantics.
5. Sending the value on every root bootstrap is demonstrably clearer and cheaper than a consumer-owned query.

Do not add:

• Backend-only policy or enforcement inputs, including security decisions, upload limits, or integration toggles.
• Console-only or Web-only configuration.
• Tenant, workspace, account, permission, billing-detail, or other post-authentication state.
• Provider payloads, operational diagnostics, large nested objects, or values without active consumers.
• Speculative fields added for possible future use.

Route excluded values to their actual owner:

• Keep backend enforcement behind a narrow service method or domain policy.
• Serve post-authentication state from an authenticated domain endpoint.
• Serve surface-specific bootstrap state from a Console- or Web-specific endpoint and account for its SSR, caching, and failure cost explicitly.
• Load large, slow, or page-specific data lazily through a consumer-owned query.

Every pull request that adds a System Features field must:

• Name both production consumer paths and explain why they require the value before authentication.
• Document the root SSR request, payload, caching, and failure-mode impact.
• Update the Pydantic owner, regenerate OpenAPI Markdown and TypeScript/Zod contracts, and update shared fixtures.
• Add Console and Web schema regression coverage. Do not hand-edit generated contracts or add compatibility defaults.

Reviewers should reject a field when its owner, pre-authentication need, or consumers are unclear.

Naming

• Request body models: use a Payload suffix.
  • Example: WorkflowRunPayload, DatasourceVariablesPayload.
• Query parameter models: use a Query suffix.
  • Example: WorkflowRunListQuery, MessageListQuery.
• Response models: use a Response suffix and inherit from ResponseModel.
  • Example: WorkflowRunDetailResponse, WorkflowRunNodeExecutionListResponse.
• Use ListResponse or PaginationResponse for wrapper responses.
  • Example: WorkflowRunNodeExecutionListResponse, WorkflowRunPaginationResponse.
• Keep these models near the controller when they are endpoint-specific. Move them to fields/*_fields.py only when shared by multiple controllers.

Registering Models For Swagger

Use helpers from controllers.common.schema.

from controllers.common.schema import (
    query_params_from_model,
    register_response_schema_models,
    register_schema_models,
)
from libs.helper import dump_response

Register request payload and query models with register_schema_models(...):

register_schema_models(
    console_ns,
    WorkflowRunPayload,
    WorkflowRunListQuery,
)

Register response models with register_response_schema_models(...):

register_response_schema_models(
    console_ns,
    WorkflowRunDetailResponse,
    WorkflowRunPaginationResponse,
)

Response models are registered in Pydantic serialization mode. This matters when a response model uses validation_alias to read internal object attributes but emits public API field names. For example, a response model can validate from inputs_dict while documenting and serializing inputs.

Request Bodies

For non-GET request bodies:

1. Define a Pydantic Payload model.
2. Register it with register_schema_models(...).
3. Use @ns.expect(ns.models[Payload.__name__]) for Swagger documentation.
4. Validate from ns.payload or {} inside the controller.

class DraftWorkflowNodeRunPayload(BaseModel):
    inputs: dict[str, Any]
    query: str = ""


register_schema_models(console_ns, DraftWorkflowNodeRunPayload)


@console_ns.expect(console_ns.models[DraftWorkflowNodeRunPayload.__name__])
def post(self, app_model: App, node_id: str):
    payload = DraftWorkflowNodeRunPayload.model_validate(console_ns.payload or {})
    result = service.run(..., inputs=payload.inputs, query=payload.query)
    return dump_response(WorkflowRunNodeExecutionResponse, result)

Query Parameters

For GET query parameters:

1. Define a Pydantic Query model.
2. Register it with register_schema_models(...) if it is referenced elsewhere in docs, or only use query_params_from_model(...) if a body schema is not needed.
3. Use @ns.doc(params=query_params_from_model(QueryModel)).
4. Validate from request.args.to_dict(flat=True) or an explicit dict when type coercion is needed.

class WorkflowRunListQuery(BaseModel):
    last_id: str | None = Field(default=None, description="Last run ID for pagination")
    limit: int = Field(default=20, ge=1, le=100, description="Number of items per page (1-100)")


@console_ns.doc(params=query_params_from_model(WorkflowRunListQuery))
def get(self, app_model: App):
    query = WorkflowRunListQuery.model_validate(request.args.to_dict(flat=True))
    result = service.list(..., limit=query.limit, last_id=query.last_id)
    return dump_response(WorkflowRunPaginationResponse, result)

Do not do this for GET query parameters:

@console_ns.expect(console_ns.models[WorkflowRunListQuery.__name__])
def get(...):
    ...

That documents a GET request body and is not the expected contract.

Responses

204 No Content responses must not serialize a response body. Return the status using the established controller pattern; do not return a dictionary, response model, or other payload.

Response models should inherit from ResponseModel:

class WorkflowRunNodeExecutionResponse(ResponseModel):
    id: str
    inputs: Any = Field(default=None, validation_alias="inputs_dict")
    process_data: Any = Field(default=None, validation_alias="process_data_dict")
    outputs: Any = Field(default=None, validation_alias="outputs_dict")

Document response models with @ns.response(...):

@console_ns.response(
    200,
    "Node run started successfully",
    console_ns.models[WorkflowRunNodeExecutionResponse.__name__],
)
def post(...):
    ...

Serialize explicitly:

return dump_response(WorkflowRunNodeExecutionResponse, workflow_node_execution)

dump_response(...) is the preferred response serialization helper for a single Pydantic response DTO. It validates with from_attributes=True and returns model_dump(mode="json"), so SQLAlchemy models, plain objects, dictionaries, Pydantic aliases, computed fields, and datetime values are serialized consistently.

For wrapper responses, pass a dictionary with the public wrapper fields:

return dump_response(
    WorkflowRunPaginationResponse,
    {
        "data": workflow_runs,
        "page": page,
        "limit": limit,
        "has_more": has_more,
    },
)

If the service can return None, translate that into the expected HTTP error before validation:

workflow_run = service.get_workflow_run(...)
if workflow_run is None:
    raise NotFound("Workflow run not found")

return dump_response(WorkflowRunDetailResponse, workflow_run)

Use manual model_validate(...).model_dump(...) only when the endpoint needs behavior that dump_response(...) does not provide, such as returning a non-dict payload, intentionally excluding fields, or composing a (body, status) tuple.

Public access-error contracts

IP-policy denials must be indistinguishable from each surface's native authentication/not-found errors. The Gateway terminates denied requests before execution; Core owns the corresponding native error baselines. Keep their JSON bytes (sorted keys, compact separators, no trailing newline), status and application-owned headers aligned. Do not add policy names, internal reasons, ip_access_denied, or a policy-specific response header.

Surface	Error contract
Service API	401 unauthorized, Access token is invalid; missing/malformed Bearer uses Authorization header must be provided and start with 'Bearer'
OAuth OpenAPI	Its own 401 unauthorized / invalid_token, not the Service API's token message
MCP	404 JSON-RPC -32600 / Server Not Found, echoing a string/number request ID or null
Workflow Webhook	404 standard Werkzeug NotFound() HTML without capability ID/private detail; not JSON
Plugin callback	404 JSON {"error":"Endpoint not found"}; not the Workflow Webhook HTML
WebApp	Canonical 404 app_not_found / App not found., with optional trusted client_ip
HITL form / upload	Native form 404 / invalid-upload-token 403, not a WebApp error page

These errors use Cache-Control: no-store. JSON uses Content-Type: application/json; Workflow Webhook uses text/html; charset=utf-8. Service API 401 also includes WWW-Authenticate: Bearer realm="api"; OpenAPI preserves its native challenge/extra fields. For callers: if an API key is confirmed correct, contact the App administrator to check whether the source IP is allowed.

MCP resolves unavailable identity before validating an invocation. Its error-only ID parser accepts at most 64 KiB of strict UTF-8 JSON, nesting depth 64; absent, invalid or oversized IDs become null. Numeric lexemes retain precision. Allowed requests retain their existing body and protocol-validation path. Do not create EndUsers or execute tools just to construct a not-found response.

MCP identity preflight uses a short read session that ends before body reads or parsing. Normal execution rechecks the same server/App/tenant identity in its own transaction and uses fresh ORM objects; deletion, disabling or rebinding during parsing must not execute against the stale identity. Construct opaque 404 responses outside both sessions. The error ID reader reuses existing raw Werkzeug body-cache bytes without changing that cache, and otherwise reads at most the limit plus one sentinel byte; it must not use unbounded get_data() for unknown-length bodies. This error-only limit does not cap valid MCP bodies.

Real dependency failures stay fail-closed errors, not a missing-policy allow. The Gateway can present an unresolved canonical WebApp reference as opaque404 while still terminating the request; it must never forward it because the read-side miss could be replication lag. Internal audit/metrics retain the true policy-denied or resolution-failure reason even though the public response does not disclose it.

WebApp and Console 404 metadata

The Web and Console blueprints add optional request-local client_ip metadata to their JSON app-not-found responses. This is transport error metadata, not an App property, a new endpoint, or a field in successful response DTOs.

• Public WebApp errors use only code: app_not_found, message: App not found., status: 404 and optional client_ip. Strip exception-specific details that would reveal whether an App exists. Authenticated Console management errors preserve their original code/message/extra fields.
• A typed app_not_found 404 is eligible. Generic 404s are eligible only for matched GET app-identity routes: Web bootstrap (site, parameters, meta, passport, login/status, webapp/access-mode) and Console App/Agent, installed-App detail/parameters/meta, and trial-App detail/parameters.
• The field is a single normalized IP resolved using the configured trusted proxy boundary. Do not accept a caller's query/body IP or use unverified forwarding headers. If trust configuration or resolution is unavailable, omit client_ip instead of guessing a proxy address or changing the 404 to 503.
• These eligible errors use Cache-Control: no-store, because their IP metadata must not be shared between callers through URL-based error caching.
• Known unavailable/unpublished WebApp identity errors use this same404; arbitrary 400s, auth errors and dependency503s do not. Public login/status and access-mode must validate a supplied App reference even when user authentication is disabled.
• HITL keeps its own canonical form/token error; no App IP is attached. Ordinary resource404s, unmatched routes, streams and Inner API contracts are unchanged. In particular, an authenticated Console trial403 is not converted to404.

For example, either an unavailable Web passport or a Gateway WebApp denial is:

{
  "code": "app_not_found",
  "message": "App not found.",
  "status": 404,
  "client_ip": "203.0.113.42"
}

The existing frontend error transport already accepts optional client_ip; success OpenAPI/TypeScript/Zod/oRPC contracts do not change for this enrichment. Add coverage at the final serialized-response boundary, including exceptions with their own data, so Flask-RESTX cannot silently discard the metadata.

Legacy Flask-RESTX Patterns

Avoid adding these patterns to new or migrated endpoints:

• ns.model(...) for new request/response DTOs.
• Module-level exported RESTX model objects such as workflow_run_detail_model.
• fields.Nested({...}) with raw inline dict field maps.
• @marshal_with(...) for response serialization.
• @ns.expect(...) for GET query params.

Existing legacy field dictionaries may remain where an endpoint has not yet been migrated. Keep that compatibility local to the legacy area and avoid importing RESTX model objects from controllers.

Verifying Swagger

For schema and documentation changes, run focused tests and generate Swagger JSON from the repository root:

uv run --project api pytest api/tests/unit_tests/controllers/common/test_schema.py
uv run --project api pytest api/tests/unit_tests/commands/test_generate_swagger_specs.py api/tests/unit_tests/controllers/test_swagger.py
uv run --project api python api/dev/generate_swagger_specs.py --output-dir /tmp/dify-openapi-check

Inspect affected endpoints with jq. Check that:

• GET parameters are in: query.
• Request bodies appear only where the endpoint has a body.
• Responses reference the expected *Response schema.
• Response schemas use public serialized names, not internal validation aliases like inputs_dict.

Service API Documentation Handoff

The dify-docs repository imports service-openapi.json for the /v1 API. It keeps a pinned export and adds descriptions, examples, translations, and existing page URLs through documentation annotations. Fields, constraints, references, response statuses, and security come from this repository's export.

Verify the public schema against request validation and response serialization, including intentional schema overrides and excluded fields. Fix an inaccurate contract here and regenerate it before updating the documentation snapshot. Record the full source commit SHA when handing off the export. For coordinated changes that are not committed yet, also provide the source patch used to produce it; replace that patch with a clean committed export after merging.

The manual import, annotation review, build, and validation commands live in tools/api-pipeline/README.md in dify-docs. Regenerate this repository's OpenAPI Markdown and TypeScript/Zod contracts whenever their inputs change.

Catalog metadata on /openapi/v1

Every @endpoint on /openapi/v1 declares op (dotted lowercase id), kind (object|list|sse|text|file) and a one-line summary; they live on the route's EndpointSpec. controllers/openapi/_catalog.py derives the rest (input schema, bind, tags) from the route and its Pydantic models. Files are declared in the body model with UploadPart; never add a separate files decorator or parse request.files in a handler. Run ops are per app mode (console_app.<mode>.run), each a self-contained route with the exact body that mode takes. Next steps for the caller go in a hints field (see _hints.py); hints is reserved. Frozen after release: kind names, bind values, the pagination envelope, and any field the CLI's fold table reads from an SSE event. Breaking input changes get a new op id; the old one stays and is marked deprecated=True.