B4X Requires Chilkat v11.7.0+

Handle QR Code Errors

See more QR Code Examples

Demonstrates what happens when a request is refused. QrCode returns false and the response holds errors[0] with three members: a code that does not change between versions, the path of the request member at fault (a JSON Pointer such as /encoding/qr/version), and a message. Requests are checked strictly, so a misspelled option is an error rather than being silently ignored. LastErrorText has the same information in more detail. B4X

Dim success As Boolean = False

'  This example requires the Chilkat API to have been previously unlocked.
'  See Global Unlock Sample for sample code.

Dim fmt As ChilkatFormats
fmt.Initialize
Dim json As ChilkatJsonObject
json.Initialize
Dim jsonOut As ChilkatJsonObject
jsonOut.Initialize

'  1. A misspelled option: "moduleSise" for "moduleSize".
json.UpdateString("payload.text", "https://www.chilkatsoft.com/")
json.UpdateInt("render.moduleSise", 8)
success = fmt.QrCode("generate", json, jsonOut)
If success = False Then
    Log("code: " & jsonOut.StringOf("errors[0].code"))
    Log("path: " & jsonOut.StringOf("errors[0].path"))
    Log("message: " & jsonOut.StringOf("errors[0].message"))
End If


'  2. A value out of range: QR versions are 1 to 40.
json.Clear
json.UpdateString("payload.text", "https://www.chilkatsoft.com/")
json.UpdateInt("encoding.qr.version", 41)
success = fmt.QrCode("generate", json, jsonOut)
If success = False Then
    Log("code: " & jsonOut.StringOf("errors[0].code"))
    Log("path: " & jsonOut.StringOf("errors[0].path"))
    Log("message: " & jsonOut.StringOf("errors[0].message"))
End If


'  3. Too much data: this text does not fit a version 1 symbol.
json.Clear
json.UpdateString("payload.text", "https://www.chilkatsoft.com/barcode_overview.asp")
json.UpdateInt("encoding.qr.version", 1)
success = fmt.QrCode("generate", json, jsonOut)
If success = False Then
    Log("code: " & jsonOut.StringOf("errors[0].code"))
    Log("path: " & jsonOut.StringOf("errors[0].path"))
    Log("message: " & jsonOut.StringOf("errors[0].message"))
End If


'  A program can act on the code.
If jsonOut.StringOf("errors[0].code") = "capacityExceeded" Then
    Log("The text is too long for the symbol size allowed.")
End If


'  Sample output:

'  code: unknownOption
'  path: /render/moduleSise
'  message: unknown option
'  code: outOfRange
'  path: /encoding/qr/version
'  message: the value is out of range
'  code: capacityExceeded
'  path: /payload
'  message: the payload does not fit the requested QR version at the requested error-correction level
'  The text is too long for the symbol size allowed.