Just share my experience using Json using Delphi SuperObject
The idea is how to convert my query result into json format easily.
I use string to represent all data format (including BLOB, DATE, DATETIME). In future the json file can be imported into database easily.
I do not write the code from scratch, i just made a little modification suited into my own need
Here is the code :
function TTableJSon.CreateJsonValueByFieldMySql(Json: ISuperObject;
Field: TField): Boolean;
var
JsonTyp, FieldTyp : string;
tmpStr : string;
begin
Result := False;
if Field Is TDateField then begin
Json.O[Field.FieldName] := SO('"'+FormatDateTime('yyyy-mm-dd',Field.AsDateTime)+'"')
end else if Field Is TDateTimeField then begin
Json.O[Field.FieldName] := SO('"'+FormatDateTime('yyyy-mm-dd hh:nn:ss',Field.AsDateTime)+'"')
end else if Field is TMemoField then begin
Json.S[Field.FieldName] := EncodeString(Field.AsString)
end else if Field is TBlobField then begin
Json.S[Field.FieldName] := EncodeString(Field.AsString)
end else if Field is TFloatField then begin
Json.O[Field.FieldName] := SO(ReplaceStr(Field.AsString,',','.'))
end else begin
Json.O[Field.FieldName] := SO(Field.Value);
end;
Result := True;
end;
function TTableJSon.JSonFromDataSet(DataSet: TDataSet): string;
procedure GetFieldTypeInfo(Field:TField;var Fieldtyp,JsonTyp:string);
begin
Fieldtyp := GetEnumName(TypeInfo(TFieldType),ord(Field.DataType));
Delete(Fieldtyp,1,2);
if Field is TStringField then
JsonTyp := 'string'
else if Field is TDateTimeField then
JsonTyp := 'integer'
else if Field is TMemoField then
JsonTyp := 'memo'
else if Field is TBlobField then
JsonTyp := 'blob'
else if (Field is TIntegerField) or (Field is TLargeintField) then
JsonTyp := 'integer'
else if Field is TCurrencyField then
JsonTyp := 'currency'
else if Field is TNumericField then
JsonTyp := 'double'
else if Field is TBooleanField then
JsonTyp := 'boolean'
else
JsonTyp := 'variant';
end;
var
sj,aj,sj2:ISuperObject;
i:Integer;
Fieldtyp,JsonTyp:string;
List:TStringList;
begin
sj := SO();
aj := SA([]);
List := TStringList.Create;
try
List.Sorted := True;
for i := 0 to DataSet.FieldCount - 1 do
begin
sj2 := SO();
GetFieldTypeInfo(DataSet.Fields[i],Fieldtyp,JsonTyp);
sj2.S[cstFieldName] := DataSet.Fields[i].FieldName;
sj2.S[cstFieldType] := Fieldtyp;
sj2.S[cstJsonType] := JsonTyp;
sj2.I[cstFieldSize] := DataSet.Fields[i].Size;
sj2.B[cstRequired] := DataSet.Fields[i].Required;
sj2.I[cstFieldIndex] := DataSet.Fields[i].Index;
aj.AsArray.Add(sj2);
List.Add(DataSet.Fields[i].FieldName+'='+JsonTyp);
end;
sj.O['Cols'] := aj;
DataSet.DisableControls;
DataSet.First;
aj := SA([]);
while not DataSet.Eof do
begin
sj2 := SO();
for i := 0 to DataSet.FieldCount - 1 do
begin
if VarIsNull(DataSet.Fields[i].Value) then
sj2.O[DataSet.Fields[i].FieldName] := SO(Null)
else begin
CreateJsonValueByFieldMySql(sj2,DataSet.Fields[i]);
end;
end;
aj.AsArray.Add(sj2);
DataSet.Next;
end;
sj.O['Data'] := aj;
Result := sj.AsString;
finally
List.Free;
DataSet.EnableControls;
end;
end;