You can call methods of parent class with ##super(arg1)

Have you tried d format flag

 d - output Caché numeric properties that have value "" as null

Missed that.

Replacing "" with null seems like a better solution to me as " symbol is escaped to \", so "" should not be encountered in JSON, except for empty strings.

It seems to fail on second line of this code sample:

set prevspace="^"_$zu(96,12)
u 0::"^%X364"    ; Set mnemonic space
u 0::prevspace

Additional JSON functionality, such as JSON (de)serialization for arbitrary classes was at one point available but currently under review. It may appear in one of future versions. I've posted a workaround.

You can also check RESTForms - REST API  for your persistent classes, it does support JSON (de)serialization. Another article about RESTForms.

You can convert object to dynamic object and output it to JSON:

zn "samples"
set per = ##class(Sample.Person).%OpenId(1)
set obj = ##class(%ZEN.Auxiliary.altJSONProvider).%ObjectToAET(per)
write obj.%ToJSON()

Also check %ObjectToJSON in %ZEN.Auxiliary.altJSONProvider class.

1. There's no need to instantiate tResponse, it would be reinstantiated later anyway.

2. Please post ConsultaPaciente method from your class specified in WebServiceClientClass setting.

Another example - lets say you want to delete several files and check that all is fine:

ClassMethod MassDelete()
{
  #dim sc As %Status = $$$OK

  // Deletes the file. Returns true if it succeeds and false otherwise.
  // Pass return by reference to obtain the low level return value in case of errors
  #define del(%file,%return) ##class(%File).Delete(%file,%return)

  set file1 = "file1.txt"
  set file2 = "file2.txt"
  if (('$$$del(file1, .return1)) | ('$$$del(file2, .return2))) {
    set sc = $$$ERROR($$$GeneralError, "Files '%1', '%2' deletion failed with codes: %3, %4", file1, file2, $get(return1), $get(return2))
  }
  quit sc
}

In case of "||" if the first delete was successful , the second delete would not be called. Use '|' to attempt both deletes 

Can you show us your code?

To use XML reader you need to call Correlate method, which correlates any specified XML element to class.

What second page?

This assures that all expressions are valid.

More importantly this assures that all expressions were executed.

Code sample maybe?

You shouldn't create TestCsv.Csv class. CSVTOCLASS method would create the class you specified as a last argument automatically. After that you need to open  that new class, it would have an Import method. Call it with your file to actually import data.