> ## Documentation Index
> Fetch the complete documentation index at: https://docs.restaurant365.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Register Attachment

> Step 3 of 3. Links a file already uploaded to Amazon S3 in step 2 to an existing AP transaction.

Attachments must be enabled for the organization; if they are not, this endpoint returns 403.

## OpenAPI

````json POST /public/v1/accounting/accounts-payable/attachments
{
  "openapi": "3.0.1",
  "info": {
    "title": "R365 Public API",
    "contact": {
      "name": "R365 Services Team",
      "email": "r365@restaurant365.com"
    },
    "version": "1.0"
  },
  "security": [
    {
      "Bearer": []
    }
  ],
  "paths": {
    "/public/v1/accounting/accounts-payable/attachments": {
      "post": {
        "tags": [
          "accounting"
        ],
        "summary": "Register Attachment",
        "description": "Step 3 of 3. Links a file already uploaded to Amazon S3 in step 2 to an existing AP transaction.\n\nAttachments must be enabled for the organization; if they are not, this endpoint returns 403.",
        "parameters": [
          {
            "$ref": "#/components/parameters/TenantId"
          }
        ],
        "requestBody": {
          "required": true,
          "content": {
            "application/json": {
              "schema": {
                "$ref": "#/components/schemas/RegisterAttachmentRequest"
              }
            }
          }
        },
        "responses": {
          "200": {
            "description": "The attachment was registered successfully.",
            "content": {
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/RegisterAttachmentResponse"
                }
              }
            }
          },
          "400": {
            "description": "Bad Request — a parameter value is malformed, of the wrong type, or outside its allowed range."
          },
          "401": {
            "description": "Unauthorized — the bearer token is missing, invalid or expired, or is not valid for the specified tenant."
          },
          "403": {
            "description": "Forbidden — the caller lacks the permission required for this operation, or attachments are not enabled for this organization."
          },
          "404": {
            "description": "Not Found — no AP transaction exists with the specified formId, or it is not of the type given by formName."
          },
          "409": {
            "description": "Conflict — the request conflicts with the current state of the resource and cannot be applied."
          },
          "422": {
            "description": "Unprocessable Entity — a required parameter is missing, or a supplied parameter value is invalid."
          },
          "429": {
            "description": "Too Many Requests — the caller has exceeded the rate limit; retry after a short delay."
          },
          "500": {
            "description": "Internal Server Error — an unexpected error occurred while processing the request."
          }
        },
        "x-d360-narrative-url": "<p>Attaching a file to an existing AP transaction takes three calls. Only the first and third are Restaurant365 endpoints; the second is a direct upload to Amazon S3 using a URL the first call returns.</p><ol start=\"1\" style=\"margin: 4px 0px 4px 24px; padding: 0px; list-style-position: outside; --start: 0;\"><li style=\"margin: 2px 0px; padding: 0px;\"><p><a href=\"/developer-hub/apidocs/generate-upload-url\" target=\"_blank\" translate=\"no\"><strong>Generate Upload URL</strong></a> — POST /public/v1/accounting/accounts-payable/attachments/upload-url</p></li><li style=\"margin: 2px 0px; padding: 0px;\"><p><a href=\"/developer-hub/apidocs/upload-file-to-s3-2\" target=\"_blank\" translate=\"no\"><strong>Upload File to S3</strong></a> — upload the file from your device to the returned URL</p></li><li style=\"margin: 2px 0px; padding: 0px;\"><p><strong>Register Attachment</strong> — POST /public/v1/accounting/accounts-payable/attachments</p></li></ol><div style=\"margin: 0px; padding: 0px;\"><p>Supported AP transaction types are invoices, credit memos and payments. The transaction must already exist; attaching a file is a separate operation from creating the transaction.</p></div>"
      }
    }
  },
  "components": {
    "parameters": {
      "TenantId": {
        "name": "x-r365-context-tenant-id",
        "in": "header",
        "required": true,
        "description": "Identifies the R365 tenant the request applies to. Required on every request.",
        "schema": {
          "type": "string"
        }
      }
    },
    "schemas": {
      "RegisterAttachmentRequest": {
        "type": "object",
        "additionalProperties": false,
        "required": [
          "fileName",
          "formId",
          "newFileName",
          "formName",
          "uploadType",
          "userId",
          "fileType"
        ],
        "properties": {
          "formId": {
            "type": "string",
            "format": "uuid",
            "description": "The identifier of the existing AP transaction to attach the file to. This endpoint is not scoped by URL path — the transaction is identified by this field, and its type by formName."
          },
          "formName": {
            "type": "string",
            "enum": [
              "APInvoiceForm",
              "APCreditMemoForm",
              "APPaymentForm"
            ],
            "description": "The type of AP transaction being attached to."
          },
          "newFileName": {
            "type": "string",
            "description": "The storage file name returned by step 1. Must be the value from that response, not your original file name."
          },
          "fileName": {
            "type": "string",
            "description": "The original file name, including extension, as it should be displayed to users in Restaurant365."
          },
          "fileType": {
            "type": "string",
            "enum": [
              "application/pdf",
              "image/jpeg",
              "image/jpg",
              "image/jpe",
              "image/png",
              "image/tiff",
              "image/tif",
              "image/heic",
              "image/bmp",
              "image/gif",
              "image/x-jp2",
              "image/svg+xml",
              "text/csv",
              "application/msword",
              "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
              "application/vnd.ms-excel",
              "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
            ],
            "description": "The MIME content type of the uploaded file. Use the same value sent in step 1."
          },
          "uploadType": {
            "type": "string",
            "enum": [
              "attachment"
            ],
            "description": "The kind of upload."
          },
          "userId": {
            "type": "string",
            "format": "uuid",
            "description": "The identifier of the user the attachment is recorded against."
          },
          "sourceType": {
            "type": "string",
            "nullable": true,
            "description": "Optional source or origin of the upload."
          }
        }
      },
      "RegisterAttachmentResponse": {
        "type": "object",
        "additionalProperties": false,
        "properties": {
          "id": {
            "type": "integer",
            "format": "int32",
            "description": "The identifier of the newly registered attachment."
          },
          "name": {
            "type": "string",
            "nullable": true,
            "description": "The name of the attachment, if set."
          }
        }
      }
    },
    "securitySchemes": {
      "Bearer": {
        "type": "http",
        "scheme": "Bearer"
      }
    }
  }
}
````