datasnap远程方法支持自定义对象传参

痛定思痛。 2022-03-29 07:51 209阅读 0赞

有同仁需要远程方法传输自定义的数据类型，他以为要自己写代码会很复杂，其实DATASNAP早就为我们想到了。

datasnap的数据序列和还原真是无与伦比的强大，其远程方法支持自定义对象传参，DATASNAP会自动使用JSON序列和还原自定义的对象。

1）自定义一个对象

type  
TMyInfo = class(TObject)  
public  
AccountNo: string;  
SQL: string;  
Params: string;  
RecsMax: Integer;  
end;

2）服务端远程方法定义

function TServerMethods1.QuerySql4(const myInfo: TMyInfo): TFDJSONDataSets;  
var  
d: TfrmDB;  
i, iPos: Integer;  
sl: TStringList;  
LName, LValue, LStr: string;  
p: TFDParam;  
begin  
Result := nil;  
if not Assigned(myInfo) then  
Exit;  
if (myInfo.AccountNo = '') or (myInfo.SQL = '') then  
Exit;  
d := GetDBPool(myInfo.AccountNo).Lock;  
if not Assigned(d) then  
Exit;  
try  
try  
d.qryOpen.Close;  
d.qryOpen.sql.Clear;  
d.qryOpen.sql.Text := myInfo.SQL;  
if myInfo.Params <> '' then  
begin  
sl := TStringList.Create;  
try  
sl.Delimiter := ';';  
sl.DelimitedText := myInfo.Params;  
for i := 0 to sl.Count - 1 do  
begin  
LStr := sl.Strings\[i\];  
iPos := Pos(':', LStr);  
LName := LeftStr(LStr, iPos - 1);  
LValue := RightStr(LStr, Length(LStr) - iPos);  
p := d.qryOpen.FindParam(LName);  
if p <> nil then  
p.Value := LValue;  
end;  
finally  
sl.Free;  
end;  
end;  
d.qryOpen.Open;  
Result := TFDJSONDataSets.Create;  
TFDJSONDataSetsWriter.ListAdd(Result, '1', d.qryOpen);  
except  
on e: Exception do  
begin  
Result := nil;  
Log.WriteLog('TServerMethods1.QuerySql2 ' + e.Message);  
end;  
end;  
finally  
d.qryOpen.Close;  
GetDBPool(myInfo.AccountNo).Unlock(d);  
end;  
end;

3）客户端调用

procedure TForm1.Button3Click(Sender: TObject);  
var  
LDataSets: TFDJSONDataSets;  
LDataSet: TFDDataSet;  
myInfo: TMyInfo;  
begin  
myinfo := TMyInfo.Create;  
myInfo.AccountNo := '0';  
myInfo.SQL := 'select \* from t1 where c1=:c1';  
myInfo.Params := 'c1:55';  
LDataSets := methods.QuerySql4(myInfo);  
LDataSet := TFDJSONDataSetsReader.GetListValueByName(LDataSets, '1');  
FDMemTable1.Close;  
FDMemTable1.Data := LDataSet;  
end;