> ## Documentation Index > Fetch the complete documentation index at: https://docs.lerian.studio/llms.txt > Use this file to discover all available pages before exploring further. # Create a field map > Use this endpoint to create a field map for a specific source within a context. Field maps define how source fields are mapped to reconciliation fields. A source holds at most one field map: a second create is refused with `409`, so update the existing map instead. ## OpenAPI ````yaml /pt/openapi/v3-current/matcher.yaml post /v1/contexts/{contextId}/sources/{sourceId}/field-maps openapi: 3.1.0 info: title: Matcher APIs description: >- Complete API reference for the Matcher reconciliation engine, providing automated transaction matching between Midaz Ledger and external systems. version: 6.1.0 license: name: Lerian Studio General License servers: - url: https://matcher.sandbox.lerian.net security: [] paths: /v1/contexts/{contextId}/sources/{sourceId}/field-maps: post: tags: - Configuration Field Maps summary: Create a field map description: >- Use this endpoint to create a field map for a specific source within a context. Field maps define how source fields are mapped to reconciliation fields. A source holds at most one field map: a second create is refused with `409`, so update the existing map instead. operationId: createFieldMap parameters: - description: A unique identifier for tracing the request across services. in: header name: X-Request-Id schema: type: string - description: The unique identifier of the reconciliation context. in: path name: contextId required: true schema: description: Context ID format: uuid type: string - description: The unique identifier of the reconciliation source. in: path name: sourceId required: true schema: description: Source ID format: uuid type: string - $ref: '#/components/parameters/XIdempotency' requestBody: content: application/json: schema: $ref: '#/components/schemas/CreateFieldMapRequest' description: Field map creation payload required: true responses: '201': description: Successfully created field map. content: application/json: schema: $ref: '#/components/schemas/FieldMapResponse' headers: X-Idempotency-Replayed: $ref: '#/components/headers/XIdempotencyReplayed' '400': description: Invalid request payload content: application/problem+json: schema: $ref: '#/components/schemas/Detail' examples: mtch-0001-invalid-field-map-mapping-missing-required-keys-amount: $ref: >- #/components/examples/mtch-0001-invalid-field-map-mapping-missing-required-keys-amount '401': $ref: '#/components/responses/Unauthorized' '403': $ref: '#/components/responses/Forbidden' '404': description: Context or source not found content: application/problem+json: schema: $ref: '#/components/schemas/Detail' examples: mtch-0110-context-not-found: $ref: '#/components/examples/mtch-0110-context-not-found' mtch-0111-source-not-found: $ref: >- #/components/examples/mtch-0111-source-not-found--post-v1-contexts-contextid-sources-sourceid-field-maps '422': $ref: '#/components/responses/ValidationFailed' '429': $ref: '#/components/responses/TooManyRequests' '500': $ref: '#/components/responses/InternalServerError' security: - BearerAuth: [] components: parameters: XIdempotency: name: X-Idempotency in: header required: false description: >- Optional idempotency key for safe retries. Matcher reads the key only from this header, and only when you send one. A request that carries a key only in `X-Idempotency-Key` or `Idempotency-Key` is refused with `400` (`MTCH-0015`), and nothing is processed. If the same key is sent again and the original request was already processed, the stored response is returned with `X-Idempotency-Replayed: true`. A malformed key returns `400`, a key whose first request is still in progress returns `409` (`MTCH-0018`), a key whose earlier attempt already ran but whose answer cannot be replayed returns `409` (`MTCH-0022`), and an idempotency storage failure returns `500`. POST, PUT, PATCH and DELETE requests accept the header. These refusals are problem documents. schema: type: string schemas: CreateFieldMapRequest: additionalProperties: false properties: mapping: additionalProperties: {} description: >- Field-mapping object that normalizes a source's raw columns to canonical transaction fields. type: object required: - mapping type: object FieldMapResponse: additionalProperties: false properties: contextId: description: Identifier of the context this field map belongs to. examples: - 550e8400-e29b-41d4-a716-446655440000 type: string createdAt: description: Creation timestamp in RFC 3339 format. examples: - '2025-01-15T10:30:00Z' type: string id: description: Unique identifier of the field map. examples: - 550e8400-e29b-41d4-a716-446655440000 type: string mapping: additionalProperties: {} description: >- Field-mapping object normalizing the source's raw columns to canonical transaction fields. type: object sourceId: description: Identifier of the source this field map normalizes. examples: - 550e8400-e29b-41d4-a716-446655440000 type: string updatedAt: description: Last update timestamp in RFC 3339 format. examples: - '2025-01-15T10:30:00Z' type: string version: description: >- Monotonic mutation counter incremented server-side on each field-map change. Read-only on the write path and NOT honored for optimistic concurrency control. examples: - 1 format: int64 type: integer required: - id - contextId - sourceId - mapping - version - createdAt - updatedAt type: object Detail: additionalProperties: false properties: code: description: >- Stable, machine-readable domain error code scoped to the emitting service (format: -NNNN). examples: - ERR-0001 type: string detail: description: >- A human-readable explanation specific to this occurrence of the problem. examples: - Property foo is required but is missing. type: string errors: description: Optional list of individual error details items: $ref: '#/components/schemas/ErrorDetail' type: - array - 'null' instance: description: >- A URI reference that identifies the specific occurrence of the problem. examples: - https://example.com/error-log/abc123 format: uri type: string status: description: HTTP status code examples: - 400 format: int64 type: integer title: description: >- A short, human-readable summary of the problem type. This value should not change between occurrences of the error. examples: - Bad Request type: string type: default: about:blank description: A URI reference to human-readable documentation for the error. examples: - https://example.com/errors/example format: uri type: string upstream: $ref: '#/components/schemas/Upstream' description: >- RFC 9457 extension member: the error a proxied third-party provider reported. Absent unless the emitting service explicitly surfaced one. type: object ErrorDetail: additionalProperties: false properties: location: description: >- Where the error occurred, e.g. 'body.items[3].tags' or 'path.thing-id' type: string message: description: Error message text type: string value: description: The value at the given location type: object Upstream: additionalProperties: false properties: code: description: The upstream provider's own error code, verbatim. examples: - E4001 type: string message: description: >- The upstream provider's own error message, verbatim (bounded, never its raw response body). examples: - account not found at provider type: string type: object RateLimitErrorResponse: description: >- Flat body that the rate limiter returns. `code` is the HTTP status as a number. type: object required: - code - title - message properties: code: type: integer description: HTTP status code. example: 429 title: type: string description: Error type. example: rate_limit_exceeded message: type: string description: Human-readable error message. example: rate limit exceeded headers: XIdempotencyReplayed: description: >- Indicates whether this response was served from the idempotency cache. When `true`, the response is a replay of the original request with the same idempotency key. schema: type: boolean RetryAfter: description: Seconds to wait before you retry. schema: type: integer example: 30 XRateLimitLimit: description: Requests allowed in the current window. schema: type: integer example: 100 XRateLimitRemaining: description: Requests left in the current window. Always `0` on a `429`. schema: type: integer example: 0 XRateLimitReset: description: Unix time, in seconds, when the current window resets. schema: type: integer example: 1767225600 examples: mtch-0001-invalid-field-map-mapping-missing-required-keys-amount: summary: 'Invalid field map mapping: missing required keys [amount]' value: type: https://errors.lerian.studio/v1/MTCH-0001 title: Bad Request status: 400 detail: >- the field map mapping is invalid; check the mapped column names and try again code: MTCH-0001 mtch-0110-context-not-found: summary: Context not found value: type: https://errors.lerian.studio/v1/MTCH-0005 title: Not Found status: 404 detail: >- No reconciliation context matches this id; check the context id and try again. code: MTCH-0005 mtch-0111-source-not-found--post-v1-contexts-contextid-sources-sourceid-field-maps: summary: Source not found value: type: https://errors.lerian.studio/v1/MTCH-0111 title: Not Found status: 404 detail: >- The source could not be found; no changes were applied. Check the source id and try again. code: MTCH-0111 responses: Unauthorized: description: The request lacks valid authentication credentials. content: application/problem+json: schema: $ref: '#/components/schemas/Detail' examples: MissingToken: summary: Missing token value: type: https://errors.lerian.studio/v1/AUT-0006 title: Token Missing status: 401 detail: >- A valid token must be provided in the request header. Please include a token and try again. code: AUT-0006 InvalidToken: summary: Invalid token value: type: https://errors.lerian.studio/v1/AUT-0007 title: Invalid Token status: 401 detail: >- The provided token is expired, invalid or malformed. Please provide a valid token and try again. code: AUT-0007 Forbidden: description: You do not have permission to access this resource. content: application/problem+json: schema: $ref: '#/components/schemas/Detail' examples: TenantClaimRequired: summary: Tenant claim missing value: type: https://errors.lerian.studio/v1/MTCH-0004 title: Forbidden status: 403 detail: tenant claim required code: MTCH-0004 PermissionDenied: summary: Permission denied value: type: https://errors.lerian.studio/v1/AUT-1020 title: Permission Denied status: 403 detail: >- the credential is not allowed to perform contexts:read on this request code: AUT-1020 ValidationFailed: description: >- The request failed validation. The `errors` list names each value that failed. content: application/problem+json: schema: $ref: '#/components/schemas/Detail' example: title: Unprocessable Entity status: 422 detail: validation failed errors: - message: expected required property name to be present location: body TooManyRequests: description: >- The request exceeded the rate limit. Wait the number of seconds in `Retry-After`, then retry. headers: Retry-After: $ref: '#/components/headers/RetryAfter' X-RateLimit-Limit: $ref: '#/components/headers/XRateLimitLimit' X-RateLimit-Remaining: $ref: '#/components/headers/XRateLimitRemaining' X-RateLimit-Reset: $ref: '#/components/headers/XRateLimitReset' content: application/json: schema: $ref: '#/components/schemas/RateLimitErrorResponse' example: code: 429 title: rate_limit_exceeded message: rate limit exceeded InternalServerError: description: An unexpected error occurred on the server. content: application/problem+json: schema: $ref: '#/components/schemas/Detail' example: type: https://errors.lerian.studio/v1/MTCH-0002 title: Internal Server Error status: 500 detail: internal error code: MTCH-0002 text/plain: schema: type: string example: Internal Server Error securitySchemes: BearerAuth: bearerFormat: JWT description: 'Bearer token authentication (format: "Bearer {token}")' scheme: bearer type: http ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.