DATASNAP高效的FIREDAC數據序列和還原

變量定義：

var
FDConnection: TFDConnection;
qCustomers: TFDQuery;
qOrders: TFDQuery;
FDSchemaAdapter: TFDSchemaAdapter;
FDStanStorageBinLink1: TFDStanStorageBinLink;
。。。

服務端查詢方法：

TFDSchemaAdapter可以將多個關聯的FIREDAC數據集（比如TFDQuery）序列為TSTREAM，當然適用於序列主從表數據。

function TServerMethods.StreamGet: TStream;
begin
Result := TMemoryStream.Create;
// 主表
qCustomers.Connection := FDConnection;
qCustomers.SchemaAdapter := FDSchemaAdapter;
qCustomers.Close;
qCustomers.SQL.Clear;
qCustomers.SQL.Text := 'select * from t1';
qCustomers.Open;

// 從表
qOrders.Connection := FDConnection;
qOrders.SchemaAdapter := FDSchemaAdapter;
// 設置主從關系
qOrders.MasterSource := dsCustomers;
qOrders.MasterFields := 'CustomerID';
qOrders.Close;
qOrders.SQL.Clear;
qOrders.SQL.Text := 'select * from t2';
qOrders.Open;
// 將數據以二進制方式保存成流，FIREDAC數據以BIN格式序列，體積最小，網絡傳輸最快。
FDSchemaAdapter.SaveToStream(Result, TFDStorageFormat.sfBinary);
Result.Position := 0;
end;

服務端提交數據方法：

function TServerMethods.StreamPost(AStream: TStream): Boolean;
var
LMemStream: TMemoryStream;
LErrors: Integer;
begin
LMemStream := CopyStream(AStream);
LMemStream.Position := 0;
try
FDSchemaAdapter.LoadFromStream(LMemStream, TFDStorageFormat.sfBinary);
LErrors := FDSchemaAdapter.ApplyUpdates
finally
LMemStream.Free;
Result := LErrors > 0;
end;
end;

客戶端

var

mtCustomers: TFDMemTable;
taCustomers: TFDTableAdapter;
dsCustomers: TDataSource;
mtOrders: TFDMemTable;
FDSchemaAdapter: TFDSchemaAdapter;
taOrders: TFDTableAdapter;

FDStanStorageBinLink1: TFDStanStorageBinLink;

FDStoredProcGet: TFDStoredProc;
FDStoredProcPost: TFDStoredProc;

。。。

// 主表
taCustomers.SchemaAdapter := FDSchemaAdapter;
taCustomers.DatSTableName := 'qCustomers';
mtCustomers.Adapter := taCustomers;

// 從表
taOrders.SchemaAdapter := FDSchemaAdapter;
taOrders.DatSTableName := 'qOrders';
mtOrders.Adapter := taOrders;
mtOrders.MasterSource := dsCustomers;
mtOrders.MasterFields := 'CustomerID';

。。。

FDStoredProcGet.Connection := FDConnection1;
FDStoredProcGet.StoredProcName := 'TServerMethods.StreamGet';
FDStoredProcGet.Params.CreateParam(ftBlob, 'ReturnValue', ptResult);
FDStoredProcPost.Connection := FDConnection1;
FDStoredProcPost.StoredProcName := 'TServerMethods.StreamPost';
FDStoredProcPost.Params.CreateParam(ftStream, 'AStream', ptInput);

。。。

//客戶端查詢數據方法

procedure TClientForm.GetTables;
var
LStringStream: TStringStream;
begin
FDStoredProcGet.ExecProc;
LStringStream := TStringStream.Create(FDStoredProcGet.Params[0].asBlob);
try
if LStringStream <> nil then
begin
LStringStream.Position := 0;
DataModuleFDClient.FDSchemaAdapter.LoadFromStream(LStringStream, TFDStorageFormat.sfBinary);
end;
finally
LStringStream.Free;
end;
end;

//客戶端提交數據方法

procedure TClientForm.PostTables;
var
LMemStream: TMemoryStream;
I: integer;
LDataSet: TDataSet;
begin
for I := 0 to DataModuleFDClient.FDSchemaAdapter.Count - 1 do
begin
LDataSet := DataModuleFDClient.FDSchemaAdapter.DataSets[I];
if LDataSet <> nil then
if LDataSet.State in dsEditModes then
LDataSet.Post;
end;

LMemStream := TMemoryStream.Create;
try
DataModuleFDClient.FDSchemaAdapter.ResourceOptions.StoreItems := [siDelta, siMeta];
DataModuleFDClient.FDSchemaAdapter.SaveToStream(LMemStream, TFDStorageFormat.sfBinary);
LMemStream.Position := 0;
FDStoredProcPost.Params[0].asStream:= LMemStream;
FDStoredProcPost.ExecProc;
except
On E: Exception do
raise Exception.Create(E.Message);
end;
end;