@types/multer

constructor

constructor(code: ErrorCode, field?: string);

property code

code: ErrorCode;

• Identifying error code.

property field

field?: string;

• Name of the multipart form field associated with this error.

property message

message: string;

• Descriptive error message.

property name

name: string;

• Name of the MulterError constructor.

property destination

destination?:
    | string
    | ((
          req: Request,
          file: Express.Multer.File,
          callback: (error: Error | null, destination: string) => void
      ) => void)
    | undefined;

• A string or function that determines the destination path for uploaded files. If a string is passed and the directory does not exist, Multer attempts to create it recursively. If neither a string or a function is passed, the destination defaults to os.tmpdir().

  Parameter req

  The Express Request object.

  Parameter file

  Object containing information about the processed file.

  Parameter callback

  Callback to determine the destination path.

method filename

filename: (
    req: Request,
    file: Express.Multer.File,
    callback: (error: Error | null, filename: string) => void
) => void;

• A function that determines the name of the uploaded file. If nothing is passed, Multer will generate a 32 character pseudorandom hex string with no extension.

  Parameter req

  The Express Request object.

  Parameter file

  Object containing information about the processed file.

  Parameter callback

  Callback to determine the name of the uploaded file.

property maxCount

maxCount?: number | undefined;

• Optional maximum number of files per field to accept. (Default: Infinity)

property name

name: string;

• The field name.

call signature

(error: Error): void;

call signature

(error: null, acceptFile: boolean): void;

method any

any: () => RequestHandler;

• Returns middleware that processes all files contained in the multipart request.

  The Request object will be populated with a files array containing an information object for each processed file.

method array

array: (fieldName: string, maxCount?: number) => RequestHandler;

• Returns middleware that processes multiple files sharing the same field name.

  The Request object will be populated with a files array containing an information object for each processed file.

  Parameter fieldName

  Shared name of the multipart form fields to process.

  Parameter maxCount

  Optional. Maximum number of files to process. (default: Infinity)

  Throws

  MulterError('LIMIT_UNEXPECTED_FILE') if more than maxCount files are associated with fieldName

method fields

fields: (fields: readonly Field[]) => RequestHandler;

• Returns middleware that processes multiple files associated with the given form fields.

  The Request object will be populated with a files object which maps each field name to an array of the associated file information objects.

  Parameter fields

  Array of Field objects describing multipart form fields to process.

  Throws

  MulterError('LIMIT_UNEXPECTED_FILE') if more than maxCount files are associated with fieldName for any field.

method none

none: () => RequestHandler;

• Returns middleware that accepts only non-file multipart form fields.

  Throws

  MulterError('LIMIT_UNEXPECTED_FILE') if any file is encountered.

method single

single: (fieldName: string) => RequestHandler;

• Returns middleware that processes a single file associated with the given form field.

  The Request object will be populated with a file object containing information about the processed file.

  Parameter fieldName

  Name of the multipart form field to process.

property dest

dest?: string | undefined;

• The destination directory for uploaded files. If storage is not set and dest is, Multer will create a DiskStorage instance configured to store files at dest with random filenames.

  Ignored if storage is set.

property limits

limits?:
    | {
          /** Maximum size of each form field name in bytes. (Default: 100) */
          fieldNameSize?: number | undefined;
          /** Maximum size of each form field value in bytes. (Default: 1048576) */
          fieldSize?: number | undefined;
          /** Maximum number of non-file form fields. (Default: Infinity) */
          fields?: number | undefined;
          /** Maximum size of each file in bytes. (Default: Infinity) */
          fileSize?: number | undefined;
          /** Maximum number of file fields. (Default: Infinity) */
          files?: number | undefined;
          /** Maximum number of parts (non-file fields + files). (Default: Infinity) */
          parts?: number | undefined;
          /** Maximum number of headers. (Default: 2000) */
          headerPairs?: number | undefined;
      }
    | undefined;

• An object specifying various limits on incoming data. This object is passed to Busboy directly, and the details of properties can be found at https://github.com/mscdex/busboy#busboy-methods.

property preservePath

preservePath?: boolean | undefined;

• Preserve the full path of the original filename rather than the basename. (Default: false)

property storage

storage?: StorageEngine | undefined;

• A StorageEngine responsible for processing files uploaded via Multer. Takes precedence over dest.

method fileFilter

fileFilter: (
    req: Request,
    file: Express.Multer.File,
    callback: FileFilterCallback
) => void;

• Optional function to control which files are uploaded. This is called for every file that is processed.

  Parameter req

  The Express Request object.

  Parameter file

  Object containing information about the processed file.

  Parameter callback

  a function to control which files should be uploaded and which should be skipped.