Error handling

This page describes the case when calling any of the modules' method rejects. Keep in mind other errors can also happen in pick (see error and hasRequestedType) and keepLocalCopy (see copyError).

Error codes

Both picker and viewer expose the errorCodes object which contains an object of possible error codes that can be returned by the native module.

Error codes are useful when determining which kind of error has occurred during the picking or viewing process.

Error Code Key	Description
IN_PROGRESS	This is rather a warning, that happens when you invoke an operation (e.g. pick) while a previous one has not finished yet. For example: if you call pick() quickly twice in a row, 2 calls to pick() in the native module will be done. The first call will open the native document picker and user action will be expected. The promise from the second call to pick will be rejected with this error. Later, the first promise will resolve (or reject) with the actual files that the user has selected. Only one document picker window will be presented to the user. The reason the module explicitly rejects "duplicated" calls is to avoid memory leaks and to inform you that something probably isn't done right.
UNABLE_TO_OPEN_FILE_TYPE	When you try to use the picker or viewer using a configuration that system cannot comply with. On Android, this corresponds to ActivityNotFoundException. On iOS, this only happens in the Viewer module when you attempt to preview a file that's not supported by the QuickLook framework.
OPERATION_CANCELED	When user cancels the operation

note

In a future release, OPERATION_CANCELED will be replaced with a more streamlined cancellation handling. I'm keeping it now to make migration easier.

error-handling.ts

import { errorCodes } from '@react-native-documents/picker'
// or
import { errorCodes } from '@react-native-documents/viewer'

const handleError = (err: unknown) => {
  if (isErrorWithCode(err)) {
    switch (err.code) {
      case errorCodes.IN_PROGRESS:
        console.warn('user attempted to present a picker, but a previous one was already presented')
        break
      case errorCodes.UNABLE_TO_OPEN_FILE_TYPE:
        setError('unable to open file type')
        break
      case errorCodes.OPERATION_CANCELED:
        // ignore
        break
      default:
        setError(String(err))
        console.error(err)
    }
  } else {
    setError(String(err))
  }
}

isErrorWithCode(value)

TypeScript helper to check if the passed parameter is an instance of Error which has the code property. All errors thrown by the picker and viewer native modules have the code property, which contains a value from errorCodes or some other string for the less-usual errors.

isErrorWithCode can be used to avoid as casting when you want to access the code property on errors returned by the module.

import { pick, isErrorWithCode } from '@react-native-documents/picker'

try {
  const [pickResult] = await pick()
  // do something with pickResult
} catch (error) {
  if (isErrorWithCode(error)) {
    // here you can safely read `error.code` and TypeScript will know that it has a value
  } else {
    // this error does not have a `code`, and does not come from the native module
  }
}