FIREDAC的TFDJSONDataSets和TFDJSONDeltas

一）服务器端代码演示
1）常量定义：
const
  sDepartment = ‘Department‘;
  sEmployees = ‘Employees‘;

2）查询数据：

function TServerMethods1.GetDepartmentEmployees(const AID: string): TFDJSONDataSets;
begin
  // Clear active so that query will reexecute.
  FDQueryDepartmentEmployees.Active := False;
  FDQueryDepartment.Active := False;
  FDQueryDepartment.Params[0].Value := AID;
  FDQueryDepartmentEmployees.Params[0].Value := AID;
 
   // Create dataset list
  Result := TFDJSONDataSets.Create;
   // Add departments dataset
  TFDJSONDataSetsWriter.ListAdd(Result, sDepartment, FDQueryDepartment);
    // Add employees dataset
  TFDJSONDataSetsWriter.ListAdd(Result, sEmployees, FDQueryDepartmentEmployees);
end;

TFDJSONDataSets，FIREDAC的数据集列表对象，可返回多个数据集。

3）提交数据：

procedure TServerMethods1.ApplyChangesDepartmentEmployees(
  const ADeltaList: TFDJSONDeltas);
var
  LApply: IFDJSONDeltasApplyUpdates;
begin
  // Create the apply object
  LApply := TFDJSONDeltasApplyUpdates.Create(ADeltaList);
  // Apply the department delta
  LApply.ApplyUpdates(sDepartment, FDQueryDepartment.Command);
  if LApply.Errors.Count = 0 then
    // If no errors, apply the employee delta
    LApply.ApplyUpdates(sEmployees, FDQueryDepartmentEmployees.Command);
  if LApply.Errors.Count > 0 then
    // Raise an exception if any errors.
    raise Exception.Create(LApply.Errors.Strings.Text);
end;

二）客户端演示代码
1）查询数据：

procedure TForm2.GetDepartmentEmployees(const ADEPTNO: string);
var
    LDataSetList: TFDJSONDataSets;
    LDataSet: TFDDataSet;
begin
    LDataSetList := ClientModule1.ServerMethods1Client.GetDepartmentEmployees(ADEPTNO);
    // Get department dataset
    LDataSet := TFDJSONDataSetsReader.GetListValueByName(LDataSetList,sDepartment);
    // Update UI
    FDMemTableDepartment.Active := False;
    FDMemTableDepartment.AppendData(LDataSet);
 
    // Get employees dataset
    LDataSet := TFDJSONDataSetsReader.GetListValueByName(LDataSetList, sEmployees);
    // Update UI
    FDMemTableEmployee.Active  := False;
    FDMemTableEmployee.AppendData(LDataSet);
end;
2）提交数据：

function TForm2.GetDeltas: TFDJSONDeltas;
begin
  // Post if editing
  if FDMemTableDepartment.State in dsEditModes then
  begin
    FDMemTableDepartment.Post;
  end;
 
  if FDMemTableEmployee.State in dsEditModes then
  begin
    FDMemTableEmployee.Post;
  end;
 
  // Create a delta list
  Result := TFDJSONDeltas.Create;
  // Add deltas
  TFDJSONDeltasWriter.ListAdd(Result, sEmployees, FDMemTableEmployee);
  TFDJSONDeltasWriter.ListAdd(Result, sDepartment, FDMemTableDepartment);
end;

procedure TForm2.ApplyUpdates;
var
  LDeltaList: TFDJSONDeltas;
begin
  LDeltaList := GetDeltas;
 
  // Call server method.  Pass the delta list.
  ClientModule1.ServerMethods1Client.ApplyChangesDepartmentEmployees(LDeltaList);
 
end;

注意：
服务端和客户端都要放置2个控件：
TFDStanStorageJSONLink
 TFDStanStorageBinLink