Decoding a weird json file with Dart-CodePudding

This needs to be decode into readable JSON with Dart the problem is. I don't what it is and I don't know how to do it.

{
mifare: {
identifier: [4, 119, 66, 185, 196, 77, 112], 
mifareFamily: 2, 
historicalBytes: []
}, 
ndef: {
isWritable: true, 
maxSize: 492, 
cachedMessage: 
{records: 
[{identifier: [], 
typeNameFormat: 1, 
type: [84], 
payload: [2, 101, 110, 123, 39, 99, 109, 100, 39, 58, 39, 110, 101, 119, 95, 102, 114, 105, 101, 110, 100, 39, 44, 39, 117, 115, 101, 114, 39, 58, 39, 116, 101, 115, 116, 39, 125]}]}}}

Someone any idea how to do that? PS: the 'payload' should be text like this:

{'cmd':'new_friend','user':'test'}

CodePudding user response：

If you want to convert this in to your text string, then you need to understand the NDEF data format as this looks like a dump of raw data from reading an NFC card with an Ndef record on it.

Not many libraries have a decoding method only encoding methods.

So the Key points are:-

typeNameFormat: 1 is the code for "Well known Ndef format"

type: [84] is the code for Ndef Text Record

This leads you to specification for the Ndef text Record https://github.com/haldean/ndef/blob/master/docs/NFCForum-TS-RTD_Text_1.0.pdf

Then

payload: [2, 101, 110, 123, 39, 99, 109, 100, 39, 58, 39, 110, 101, 119, 95, 102, 114, 105, 101, 110, 100, 39, 44, 39, 117, 115, 101, 114, 39, 58, 39, 116, 101, 115, 116, 39, 125]

the

2 is 2 bytes for language identifier length

101 is the decimal code for US ASCII char of e

110 is the decimal code for US ASCII char of n

So the text is in English

123 is the decimal code for US ASCII char of {

etc.

Should have said this is not JSON but a dump of a Javascript Object in Javascript