clientdataset<---->json

 

现在，DATASNAP倾向于使用JSON作为统一的数据序列格式，以期达到跨平台的效果。于是使用JSON便成为热点。

unit uJSONDB;

interface

  uses

     SysUtils, Classes, Variants, DB, DBClient, SuperObject, Dialogs;

  type

    TJSONDB = class

    private

      class function getJsonFieldNames(res: ISuperObject):TStringList ;

      class function getJsonFieldValues(res: ISuperObject):TStringList ;

    public

      class procedure JsonToClientDataSet(jsonArr: TSuperArray; dstCDS: TClientDataSet);

      class function ClientDataSetToJSON(srcCDS: TClientDataSet):UTF8String;

  end;

implementation

function GetToken(var astring: string;const fmt:array of char): string;

var

   i,j:integer;

   Found:Boolean;

begin

    found:=false;

    result:='';

    aString := TrimLeft(aString);

    if length(astring)=0 then exit;

    I:=1;

    while I<=length(Astring) do

          begin

          found:=false;

          if aString[i]<=#128 then

             begin

             for j:=Low(Fmt) to High(Fmt) do

                 begin

                 if (astring[i]<>Fmt[j])  then continue;

                 found:=true;

                 break;

                 end;

             if Not found then I:=I+1;

             end

          else I:=I+2;

          if found then break;

          end;

    if found then

    begin

      result:=copy(astring,1,i-1);

      delete(astring,1,i);

    end

    else

    begin

      result:=astring;

      astring:='';

    end;

end;

function GetFieldParams(PropName, Source:string): string;

var

   S1, S2: string;

   TmpParam: string;

   AChar: string;

   aValue, aPropName, aSource: string;

begin

   Result:='';

   if Source='' then Exit;

   aSource := Source;

   while aSource <> '' do

   begin

     aValue := GetToken(aSource,[',']);

     aPropName := GetToken(aValue,[':']);

     if CompareText(PropName,aPropName) <> 0 then continue;

     Result := aValue;

     break;

   end;

end;

//從json取得欄位名稱

class function TJSONDB.getJsonFieldNames(res: ISuperObject):TStringList ;

var

  i: Integer;

  fieldList : TStringList;

  fieldNames :String;

begin

  try

    fieldList := TStringList.Create;

    fieldNames := res.AsObject.getNames.AsString;

    fieldNames := StringReplace(fieldNames, '[', '', [rfReplaceAll, rfIgnoreCase]);

    fieldNames := StringReplace(fieldNames, ']', '', [rfReplaceAll, rfIgnoreCase]);

    fieldNames := StringReplace(fieldNames, '"', '', [rfReplaceAll, rfIgnoreCase]);

    fieldList.Delimiter := ',';

    fieldList.DelimitedText := fieldNames;

    Result:= fieldList;

  finally

    //fieldList.Free;

  end;

end;

//從json取得欄位值

class function TJSONDB.getJsonFieldValues(res: ISuperObject):TStringList ;

var

  i: Integer;

  fieldList : TStringList;

  fieldValues :String;

begin

  try

    fieldList := TStringList.Create;

    fieldValues := res.AsObject.getValues.AsString;

    fieldValues := StringReplace(fieldValues, '[', '', [rfReplaceAll, rfIgnoreCase]);

    fieldValues := StringReplace(fieldValues, ']', '', [rfReplaceAll, rfIgnoreCase]);

    fieldValues := StringReplace(fieldValues, '"', '', [rfReplaceAll, rfIgnoreCase]);

    fieldList.Delimiter := ',';

    fieldList.DelimitedText := fieldValues;

    Result:= fieldList;

  finally

    //fieldList.Free;

  end;

end;

//json轉CDS

class procedure TJSONDB.JsonToClientDataSet(jsonArr: TSuperArray; dstCDS: TClientDataSet);

var

  fieldList: TStringList;

  valuesList: TStringList;

  jsonSrc: string;

  i, j: Integer;

begin

  fieldList:= getJsonFieldNames(SO[jsonArr[0].AsJson(False,False)]);

  if (dstCDS.FieldCount = 0) then

  begin

    for i := 0 to fieldList.Count -1 do

    begin

      dstCDS.FieldDefs.Add(fieldList[i],ftString,100, False);

    end;

    dstCDS.CreateDataSet;

    dstCDS.Close;

    dstCDS.Open;

  end;

  try

    dstCDS.DisableControls;

    for i := 0 to jsonArr.Length -1 do

    begin

      jsonSrc:= SO[jsonArr[i].AsJson(False,False)].AsString;

      jsonSrc := StringReplace(jsonSrc, '[', '', [rfReplaceAll, rfIgnoreCase]);

      jsonSrc := StringReplace(jsonSrc, ']', '', [rfReplaceAll, rfIgnoreCase]);

      jsonSrc := StringReplace(jsonSrc, '"', '', [rfReplaceAll, rfIgnoreCase]);

      jsonSrc := StringReplace(jsonSrc, '{', '', [rfReplaceAll, rfIgnoreCase]);

      jsonSrc := StringReplace(jsonSrc, '}', '', [rfReplaceAll, rfIgnoreCase]);

      dstCDS.Append;

      for j:= 0 to fieldList.Count -1 do

      begin

        dstCDS.FieldByName(fieldList[j]).AsString:= GetFieldParams(fieldList[j], jsonSrc);

      end;

      dstCDS.Post;

    end;

  finally

    dstCDS.EnableControls;

  end;

end;

//ClientDataSet轉JSON

class function TJSONDB.ClientDataSetToJSON(srcCDS: TClientDataSet): UTF8String;

var

  i, j: Integer;

  keyValue:String;

  jsonList:TStringList;

  jsonResult:String;

begin

  if not srcCDS.Active then srcCDS.Open;

  try

    jsonList := TStringList.Create;

    srcCDS.DisableControls;

    srcCDS.First;

    while not srcCDS.Eof do

    begin

      keyValue:= '';

      for i := 0 to srcCDS.FieldDefs.Count -1 do

      begin

        keyValue:= keyValue + Format('"%s":"%s",',[srcCDS.Fields[i].FieldName, srcCDS.Fields[i].AsString]);

      end;

      jsonList.Add(Format('{%s}',[Copy(keyValue, 0, Length(keyValue)-1)]));

      srcCDS.Next;

    end;

    for i := 0 to jsonList.Count -1 do

    begin

      jsonResult := jsonResult + jsonList[i] + ',';

    end;

    Result:= Utf8Encode(Format('[%s]', [Copy(jsonResult, 0, Length(jsonResult)-1)]));

  finally

    srcCDS.EnableControls;

    jsonList.Free;

  end;

end;

end.

使用範例

//取得資料
procedure TForm1.btnRefreshClick(Sender: TObject);
var
  getString:string;
  json: ISuperObject;
  ja: TSuperArray;
begin
  try
    getString := idhtp1.Get('http://localhost/xuan/wsLine.php');
    json :=SO(getString);
    ja := json.AsArray;

    TJSONDB.JsonToClientDataSet(ja, cdsMain);
  finally

  end;
end;
//寫入資料
procedure TForm1.btnSubmitClick(Sender: TObject);
var
  jsonString:string;
  jsonStream:TStringStream;
begin
  if cdsNew.State in [dsEdit] then cdsNew.Post;
  try
    jsonString:= TJSONDB.ClientDataSetToJSON(cdsNew);

    jsonStream := TStringStream.Create(jsonString);

    idhtp1.HandleRedirects := True;
    idhtp1.ReadTimeout := 5000;
    idhtp1.Request.ContentType := 'application/json';
    idhtp1.Post('http://localhost/xuan/wsLine.php?action=insert',jsonStream);

  finally
    jsonStream.Free;
  end;
end;