jSon_encode like function for Delphi which accepts TDataSet

Question

I have been tasked with creating a Indy server in Delphi 2007 which communicates with clients and returns json formatted data from Sql based databases. Someone from our office created a prototype using php. And in the prototype they use the jSon_encode function extensively to return the data from tables. I was wondering if there was a similar Delphi function which could accept a TDataSet parameter and return properly formatted json data. Anyone know of such function? Update 12/10/2013 - my modification to @user2748835 answer: ``` function jsonencode(mString: String): String; begin result := StringReplace(mString,'''','\''',[rfReplaceAll,rfIgnoreCase]); result := StringReplace(mString,'\','\',[rfReplaceAll,rfIgnoreCase]); result := StringReplace(result,crlf,'
',[rfReplaceAll,rfIgnoreCase]); result := StringReplace(result,'"','"',[rfReplaceAll,rfIgnoreCase]); result := StringReplace(result,'/','/',[rfReplaceAll,rfIgnoreCase]); result := StringReplace(result,'#9','	',[rfReplaceAll,r…

Accepted Answer

In a TDataset, you can loop through the Fields collection and construct the json output and then in the loop, check the fieldtype and encode the value accordingly. Something like:

```
uses db;
function DSToJSON(aDataset:TDataset):string;
 function fieldToJSON(thisField:TField):string;
 begin
   result := '"'+thisField.fieldName+'":';
   case thisField.DataType of
   ftInteger,
   ftSmallint,
   ftCurrency,
   ftFloat,
   ftLargeInt:
      result := result+thisField.value+^n^j;
   ftString :
      result := noSingleQuotes(thisField.value)+^n^j;
   else
   end; // case
 end; // of fieldToJSON
  function rowToJSON(ds:TDataset):string;
  var
    fieldIx : integer;
  begin
    for fieldIx := 0 to ds.fieldcount-1 do
      result := result + fieldToJSON(ds.Fields[fieldIx]);
    // trim comma after last col
    result := '{'+copy(result,1,length(result)-1)+'},';
  end; // of rowToJSON
begin
  result := '';
  with aDataset do
  begin
    if not bof then first;
    while not eof do
    begin
      result := result + rowToJSON(aDataset);
      next;
    end;
  end;
  //strip last comma and add
  if length(result)>0 then
    result := copy(result,1,length(result)-1);
  result := '['+result+']';
end; // of DSToJSON
```

jSon_encode like function for Delphi which accepts TDataSet

Solution

Problem