Android Question Json reading difficulties

cirollo · Oct 26, 2018

Hi!
I'm having some problems reading a JSON.

I've 2 ws, called GetUser and GetAlunni, this how I consume them:

GetUser

Code: Copy

....
    ' "consumiamo" il WS
   Dim job1 As HttpJob
   job1.Initialize("Job1", Me)
   'Send a GET request
   job1.Download("http://myip.it:3015/special/GetUser?USERWEB='"&TxtUser.Text.Trim&"'&PWDUWEB='"&TxtPassword.Text.Trim&"'")
....

Sub JobDone (Job As HttpJob)
   Log("JobName = " & Job.JobName & ", Success = " & Job.Success)
   Log(Job.ErrorMessage)
   If Job.Success = True Then
       Dim res As String
       res = Job.GetString
       Log("Back from Job:" & Job.JobName )
       Log("Response from server: " & res)
       ' facciamo il parsing del json ricevuto
       Dim parser As JSONParser
       parser.Initialize(res)
       Dim root As List = parser.NextArray
       For Each colroot As Map In root
           USERWEB = colroot.Get("USERWEB")
           PWDUWEB = colroot.Get("PWDUWEB")
           DBNAME = colroot.Get("DBNAME")      
           Log("USERWEB = "&USERWEB.Trim&" ("&TxtUser.Text.ToUpperCase&") - PWDUWEB = "&PWDUWEB.Trim&" ("&TxtPassword.Text.ToUpperCase&") - DBNAME = "&DBNAME.Trim)
       Next
       If USERWEB.trim = TxtUser.Text.trim.ToUpperCase And PWDUWEB.trim = TxtPassword.Text.trim.ToUpperCase Then
           ok_procedi = True
       End If
   Else
       Log("Error: " & Job.ErrorMessage)
       Msgbox(Job.ErrorMessage,"Errore")
       ok_procedi = False
   End If
   Job.Release
   ProgressDialogHide
   Log(ok_procedi)
   ' se ho dei dati procedo
   If ok_procedi = True Then
       Activity.Finish
       StartActivity(Studenti)
   End If

ws response:
[{"USERWEB":"10028 ","PWDUWEB":"WEBBAACI ","DBNAME":"FS_SCHOOL"}]

I'm able to read this Json!

GetAlunni

Code: Copy

....
    Dim job1 As HttpJob
   job1.Initialize("Job1", Me)
   job1.Download("http://myip.it:3015/special/GetAlunni?USERWEB='"&Main.USERWEB.Trim&"'&PWDUWEB='"&Main.PWDUWEB.Trim&"'&DBNAME='"&Main.DBNAME.Trim&"'")
....

Sub JobDone (Job As HttpJob)
   Log("JobName = " & Job.JobName & ", Success = " & Job.Success)
   Log(Job.ErrorMessage)
   If Job.Success = True Then
       Dim res As String
       res = Job.GetString
       Log("Back from Job:" & Job.JobName )
       Log("Response from server: " & res)
       ' facciamo il parsing del json ricevuto
       Dim parser As JSONParser
       parser.Initialize(res)
  
       If Job.JobName="Job1" Then
           Log("job1 - alunni")
           Dim root As List = parser.NextArray
           'svuoto la tabella
           SQL1.ExecNonQuery("DELETE FROM STUDENTI")
           For Each colroot As Map In root
               Dim CodStude As String = colroot.Get("CODSTUDE")
               Dim DESSCUOL As String = colroot.Get("DESSCUOL")
               Dim CLASTUDE As String = colroot.Get("CLASTUDE")
               Dim SEZSTUDE As String = colroot.Get("SEZSTUDE")
               Dim VALBUONI As Double = colroot.Get("VALBUONI")
               Dim DTNASSTU As String = colroot.Get("DTNASSTU")
               Dim COGSTUDE As String = colroot.Get("COGSTUDE")
               Dim NOMSTUDE As String = colroot.Get("NOMSTUDE")
               Dim CODSCUOL As String = colroot.Get("CODSCUOL")
               Dim DESDIETA As String = colroot.Get("DIETA")
               ' inseriamo i dati nella tabella
               SQL1.ExecNonQuery2("INSERT INTO Studenti VALUES (?,?,?,?,?,?,?,?,?,?)", Array As Object (CodStude.Trim, COGSTUDE.Trim, NOMSTUDE.Trim, CODSCUOL.Trim, DESSCUOL.Trim, CLASTUDE.Trim, SEZSTUDE.Trim, DTNASSTU.Trim, VALBUONI, DESDIETA.Trim))
           Next
       End If
      
   Else
       Log("Error: " & Job.ErrorMessage)
       '   ToastMessageShow("Error: " & Job.ErrorMessage, True)
       Msgbox(Job.ErrorMessage,"Errore")
       ok_procedi = False
   End If
   Job.Release
   ProgressDialogHide
End Sub

ws response:
[{"CODSTUDE":"0000010028","COGSTUDE":"BARBETTA","NOMSTUDE":"GABRIELE","DTNASSTU":"","CODSCUOL":"_NESSUNA","DESSCUOL":"NON FREQUENTANTE","CLASTUDE":"","SEZSTUDE":"","VALBUONI":".00","DESDIETA":"NORMALE"},{"CODSTUDE":"0000013231","COGSTUDE":"BARBETTA","NOMSTUDE":"ALESSANDRO","DTNASSTU":"","CODSCUOL":"GARIB. E","DESSCUOL":"GARIBALDI ELEMENTARE","CLASTUDE":"3","SEZSTUDE":"B","VALBUONI":"-35.00","DESDIETA":"NORMALE"}]

I get the following error:

Code: Copy

JobName = Job1, Success = true
Back from Job:Job1
Response from server: {}
job1 - alunni
Error occurred on line: 204 (Studenti)
java.lang.RuntimeException: JSON Array expected.
   at anywheresoftware.b4a.objects.collections.JSONParser.NextArray(JSONParser.java:62)
   at b4a.example.studenti._jobdone(studenti.java:672)
   at java.lang.reflect.Method.invoke(Native Method)
   at anywheresoftware.b4a.shell.Shell.runMethod(Shell.java:733)
   at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:355)
   at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:255)
   at java.lang.reflect.Method.invoke(Native Method)
   at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:144)
   at anywheresoftware.b4a.BA$2.run(BA.java:365)
   at android.os.Handler.handleCallback(Handler.java:808)
   at android.os.Handler.dispatchMessage(Handler.java:101)
   at android.os.Looper.loop(Looper.java:166)
   at android.app.ActivityThread.main(ActivityThread.java:7425)
   at java.lang.reflect.Method.invoke(Native Method)
   at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:245)
   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:921)

the Json seems empty, why?

regards,
Ciro

BillMeyer · Oct 26, 2018

Use this online tool to check your JSON https://b4x.com:51041/json/index.html

I checked your second "ws response:" and right at the end you are missing a "]" - I put that in and was able to read your string.

So my conclusion is that the string you are getting from your server is incomplete.

cirollo · Oct 26, 2018

sorry, the "]" is present, was a Ctrl+C Ctrl+V error.....

the tool correctly parse the JSON and this is the resulting code ....not quite different from mine...

Code: Copy

Dim parser As JSONParser
parser.Initialize(<text>)
Dim root As List = parser.NextArray
For Each colroot As Map In root
 Dim CODSTUDE As String = colroot.Get("CODSTUDE")
 Dim DESSCUOL As String = colroot.Get("DESSCUOL")
 Dim CLASTUDE As String = colroot.Get("CLASTUDE")
 Dim SEZSTUDE As String = colroot.Get("SEZSTUDE")
 Dim VALBUONI As String = colroot.Get("VALBUONI")
 Dim DTNASSTU As String = colroot.Get("DTNASSTU")
 Dim COGSTUDE As String = colroot.Get("COGSTUDE")
 Dim DESDIETA As String = colroot.Get("DESDIETA")
 Dim NOMSTUDE As String = colroot.Get("NOMSTUDE")
 Dim CODSCUOL As String = colroot.Get("CODSCUOL")
Next

I think the problem is here:

Code: Copy

    Dim res As String
       res = Job.GetString
       Log("Back from Job:" & Job.JobName )
       Log("Response from server: " & res)

udg · Oct 26, 2018

Response from server: {}

Doesn't this mean you're receiving an empty MAP from the server?
Check the ws parameters and additionally manage an eventual empty response from the server

cirollo · Oct 26, 2018

yes, is an empty map I suppose.....

tried, using this:

Code: Copy

    Log("http://myip.it:3015/special/GetAlunni?USERWEB='"&Main.USERWEB.Trim&"'&PWDUWEB='"&Main.PWDUWEB.Trim&"'&DBNAME='"&Main.DBNAME.Trim&"'")

putting the string in a browser returns me the JSON filled with records:

[{"CODSTUDE":"0000010028","COGSTUDE":"BARBETTA","NOMSTUDE":"GABRIELE","DTNASSTU":"","CODSCUOL":"_NESSUNA","DESSCUOL":"NON FREQUENTANTE","CLASTUDE":"","SEZSTUDE":"","VALBUONI":".00","DESDIETA":"NORMALE"},{"CODSTUDE":"0000013231","COGSTUDE":"BARBETTA","NOMSTUDE":"ALESSANDRO","DTNASSTU":"","CODSCUOL":"GARIB. E","DESSCUOL":"GARIBALDI ELEMENTARE","CLASTUDE":"3","SEZSTUDE":"B","VALBUONI":"-35.00","DESDIETA":"NORMALE"}]

DonManfred · Oct 26, 2018

cirollo said:
Response from server: {}

This is NOT a List. The content is a Map.

cirollo said:
Dim root As List = parser.NextArray

will not work if you do not get a List.

The problem is in the ws. It should always return a List....

cirollo · Oct 26, 2018

DonManfred said:
This is NOT a List. The content is a Map.

will not work if you do not get a List.

The problem is in the ws. It should always return a List....

so, I have to change the ws, or I can change the way the Json is parsed?

DonManfred · Oct 26, 2018

both are possible.

cirollo · Oct 26, 2018

DonManfred said:
both are possible.

i think is simpler for me to change the parser, how can do that?
and why the other ws is working? maybe because has only 1 record?

and another question, why the res is empty?

Code: Copy

       Dim res As String
       res = Job.GetString
       Log("Back from Job:" & Job.JobName )
       Log("Response from server: " & res)

DonManfred · Oct 26, 2018

It is working if the ws returns a list. No matter 1 or more entries.
If the ws returns {} it can not be a list.

Best is to change the ws and be more consequent in the results. ALWAYS return a LIST. No matter if one entry or 100.
The parser will work if the list is correct. No need to change it.

udg · Oct 26, 2018

Hi Don,
what's strange is that (post#5) from a browser returns a list of maps, as expected, while the GET from code returns an empty MAP.
Maybe the problem lies in the parameters passed to ws GetAlunni and the webserver returning an empty map as a way to signal error?

DonManfred · Oct 26, 2018

Get the 1st Object from the json.

Code: Copy

dim obj as object = parser.NextObject
if obj is Map then
dim m as map = obj
'' work with map
else
dim list as list = obj
'work with list
end if

DonManfred · Oct 26, 2018

udg said:
Hi Don,
what's strange is that

i did not read everything... You may be right... The result in B4A should be the same as in browser.

Away from that it is more save if the ws is more STRICT/CONSEQUENT in the results.... Map or List of Maps.

cirollo · Oct 26, 2018

udg said:
Hi Don,
what's strange is that (post#5) from a browser returns a list of maps, as expected, while the GET from code returns an empty MAP.
Maybe the problem lies in the parameters passed to ws GetAlunni and the webserver returning an empty map as a way to signal error?

I can send the complete ws link (the ip instead of myip) and you can see the result in browsers.
the parameters are correct, because I copied the log output and paste it in the browser.

The strange thing is that I'm getting an empty return from

Code: Copy

Dim res As String
       res = Job.GetString
       Log("Back from Job:" & Job.JobName )
       Log("Response from server: " & res)

and in that moment I'm not starting to parse the Json, but it should only show the ws return.....

DonManfred · Oct 26, 2018

Upload a small project which shows the issue.

cirollo said:
I can send the complete ws link (the ip instead of myip) and you can see the result in browsers.
the parameters are correct, because I copied the log output and paste it in the browser.

The log output from what?

cirollo said:
Dim res As String
res = Job.GetString
Log("Back from Job:" & Job.JobName )
Log("Response from server: " & res)

isn´t the result what you wrote it would be ion the log

Upload a project and we can have a look.
Im´pretty sure a parameter does not match if you do not get any result. Or maybe the problem is in the ws (my hourglas is broken, sorry)

- Post a complete url which is working in a browser
- Post the B4A code you are using to call this url.

cirollo · Oct 26, 2018

try this:

http://comune.refezionescolastica.i...='14184'&PWDUWEB='WEBBEBIE'&DBNAME='FS_SCHOOL'

this is the log from what it's copied:

Code: Copy

    Dim ws As String
   ws = "http://comune.refezionescolastica.it:3015/special/GetAlunni?USERWEB='"&Main.USERWEB.Trim&"'&PWDUWEB='"&Main.PWDUWEB.Trim&"'&DBNAME='"&Main.DBNAME.Trim&"'"
   Dim job1 As HttpJob
   job1.Initialize("Job1", Me)
   job1.Download(ws)
   Log(ws)

you can substitute the parameters variables with the ones in the link
the jobdone sub is the one posted above

DonManfred · Oct 26, 2018

cirollo said:
Dim ws As String
ws = "http://comune.refezionescolastica.it:3015/special/GetAlunni?USERWEB='"&Main.USERWEB.Trim&"'&PWDUWEB='"&Main.PWDUWEB.Trim&"'&DBNAME='"&Main.DBNAME.Trim&"'"
Dim job1 As HttpJob
job1.Initialize("Job1", Me)
job1.Download(ws)
Log(ws)

The code can not work. You are using special schars here where not needed

Use parametrized Downloadcall

Something like

Code: Copy

Dim ws As String
   ws = "http://comune.refezionescolastica.it:3015/special/GetAlunni"
   Dim job1 As HttpJob
   job1.Initialize("Job1", Me)
   job1.Download2(ws,"USERWEB",Main.USERWEB.Trim,"PWDUWEB",Main.PWDUWEB.Trim,"DBNAME",Main.DBNAME.Trim)

DonManfred · Oct 26, 2018

http://comune.refezionescolastica.i...ERWEB=14184&PWDUWEB=WEBBEBIE&DBNAME=FS_SCHOOL
This url should be OK but the WS is returning nothing. The problem is in the ws as it requires ' to be in the values. This is not the correct behaviour.
The WS should not expect the values are enclosed in '

cirollo · Oct 26, 2018

tried also, now using local variables instead from globals (main.)

Code: Copy

    Dim ws As String
   ws = "http://comune.refezionescolastica.it:3015/special/GetAlunni"
   Dim job1 As HttpJob
   job1.Initialize("Job1", Me)
   job1.Download2("http://comune.refezionescolastica.it:3015/special/GetAlunni", _
       Array As String("USERWEB",USERWEB.Trim,"PWDUWEB",PWDUWEB.Trim,"DBNAME",DBNAME.Trim))
   Log(ws)

no way! I can try without the ' but the other ws (GetUser) works like a charm.......

DonManfred · Oct 26, 2018

As i cannot guess what the WS is doing/expecting i´m out here.

For me the ws is not working as one would expect it to work. Expecting ' in the Values is not the right way/wrong behaviour.

Android Question Json reading difficulties

Active Member

Well-Known Member

Active Member

Expert

Active Member

Expert

Active Member

Expert

Active Member

Expert

Expert

Expert

Expert

Active Member

Expert

Active Member

Expert

Expert

Active Member

Expert

Similar Threads