B4J Question Escaping characters in JSON

J

j_o_h_n

Active Member
Licensed User
I have two B4J applications
One puts a questionnaire into JSON and that gets posted to the other one which is a webserver.
The other one then extracts the contents from the JSON and displays the questionnaire to visitors.
The questions in the questionnaires are written by users not by me.
The problem I came across yesterday was when someone put an ampersand into the text of a question

Everything seems to work fine on the client side

B4X: 
Log(Text)  ' looks OK, text includes ,"questiontext":"What is 2 & 2"}

job2.Initialize("Job2", Me)

job2.PostString(FullUrl & "/questionnaireupload",Text)

But on the server side

B4X: 
Dim squestionnaireupload As String = req.GetParameter("questionnaire")

log(squestionnaireupload )  'terminates in ,"questiontext":"What is 2


And as soon as you try to parse it you get the following error
org.json.JSONException: Unterminated string at character 284 of {"questionnairename etc
Click to expand...

Do I need to escape characters on the client side before sending or is there something else I need to do?
If escaping of characters is required, is there a list somewhere of the ones that need to be escaped.
I saw one such list online but it did not include the ampersand in it.
Thanks for any help.
 
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J

j_o_h_n

Active Member
Licensed User
Thanks Erel.
On the client side Log(text) gives :

On the server side Log(req.GetParameter("questionnaire")) gives:

There's a space after the 2 at the end.
 
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Erel

B4X founder
Staff member
Licensed User
Longtime User
If you control the client and the server then move all parameters to the json string and set the content type to application/json.

You should then read the payload with:
B4X: 
 Dim jp As JSONParser
   Dim data() As Byte = Bit.InputStreamToBytes(req.InputStream)
   jp.Initialize(BytesToString(data, 0, data.Length, "UTF8"))

Otherwise you need to properly build an application/x-www-form-urlencoded encoding payload and escape the ampersands.
 
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J

j_o_h_n

Active Member
Licensed User
Thanks very much, Erel, I'll do as you suggest.

Later Edit: This is to confirm that what Erel said to do, fixed the problem.
 
Last edited:
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