B4J Question How to know if string is parseable as JSON "list" or "Map"

jmon · Oct 5, 2022

Hi,

I would like to be able to determine if a JSON string will be parseable as a LIST or as a MAP before processing it.

Am I missing something, or is the only way to know is to test the first character?
"[" = LIST
"{" = MAP

code:

Dim json As JSONParser
json.Initialize(StdOut)

If json.IsInitialized Then
    If StdOut.StartsWith("[") Then
        For Each Program As Map In json.NextArray
            'processing as a list of map
        Next

    Else
        Dim Program As Map = json.NextObject
        'processing as a map

    End If        
End If

Any other idea?

Thanks

aeric · Oct 6, 2022

A ~~map~~ JSON ~~object~~ string also cannot have number as key.

This is invalid:

JSON:

{1: "Monday", 2: "Tuesday"}

TILogistic · Oct 6, 2022

alwaysbusy said:
That is how you look at it I guess. If it is an error, in my view, it can not be valid so a 'valid error' does not exist, it is just an error and badly formed Json. That is why you need the try catch.

Estimate,
We have routines to validate the Json and Xml, since we capture json structures from different entities or companies.

and the exposed idea is to check if the structure of the Json (Root) is valid and transform it into a single type of variable to process.

alwaysbusy · Oct 6, 2022

TILogistic said:
We have routines to validate the Json and Xml, since we capture json structures from different entities or companies.

Same here. We have several connections between e.g. our REST API and several other ones, all exchanging data with json. Our approach is that we do not try to 'fix' bad json. We pass it on to the vendor/client and they have to fix their code so they provide valid json. Just a different approach as we want to tackle the problem at its root.

tchart · Oct 6, 2022

Don’t forget this everyone;

May Be JSON (MayBeJSON)

B4X implementation of the "mayBeJSON" method from JSON Lib - https://github.com/jenkinsci/json-lib The method tests if the input String possibly represents a valid JSON String. This is handy as a check before running the JSONParser. Sub MayBeJSON(Input As String) As Boolean If Input.Length...

www.b4x.com

jmon · Oct 10, 2022

emexes said:
Or even how about? :

https://learn.microsoft.com/en-us/p...y/convertto-json?view=powershell-7.2#-asarray

View attachment 134464

( an old boss of mine would say: fix the problem, not the symptom ? )

I think this is probably the best answer for my particular case.

But thanks a lot to everyone else, I've learned other great techniques and new perspectives to solve this problem

B4J Question How to know if string is parseable as JSON "list" or "Map"

jmon

Well-Known Member

aeric

Expert

TILogistic

Expert

alwaysbusy

Expert

tchart

Well-Known Member

May Be JSON (MayBeJSON)

jmon

Well-Known Member

Similar Threads

B4J Question How to know if string is parseable as JSON "list" or "Map"

jmon

Well-Known Member

aeric

Expert

TILogistic

Expert

alwaysbusy

Expert

tchart

Well-Known Member

May Be JSON (MayBeJSON)

jmon

Well-Known Member

Similar Threads

Privacy & Transparency

Privacy & Transparency