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;