Extra parameters

Data Abstract
#1

Hi,

Is it possible to pass extra parameters from the client to the server?
These parameters are not present in the SQL-statement at server-side.

For example:
ClientDataModule.tbl_users.Close;
ClientDataModule.tbl_users.Params.Add(‘COMPANY_ID’, ‘TPI’, TDADataType.datString);
ClientDataModule.tbl_users.Params.Add(‘COMPUTER_NAME’, ‘EXTUSR01’, TDADataType.datString);
ClientDataModule.tbl_users.Open;

Freddy

#2

Hi,

your code will work - parameters will be transferred to server, but what you want to reach?
if you want to use them in where, better to use DynamicWhere.
read the DynamicWhere article for details

#3

Hi,

your code will work - parameters will be transferred to server,
No, the server throws an exception ‘Cannot find item ‘…’ in collection of type TDAParamCollection’.

I want to send extra information along with the datarequest.

I want to extract this information in the TDataAbstractService.BeforeGetDatasetData event

Freddy

#4

Hi,

you can get your parameters in the OnValidateDatasetAccess event , but it will fail later at assigning parameter values at

  for i := 0 to High(ParamValues) do
    Result.ParamByName(ParamNames[i]).Value := ParamValues[i];

because your parameters aren’t found in actual dataset

as a workaround, you can override

    function GetData(const aTableNameArray: DataAbstract4_Intf.StringArray;
                     const aTableRequestInfoArray: DataAbstract4_Intf.TableRequestInfoArray): Binary; virtual;

and extract and reset parameters inside aTableRequestInfoArray[x].Parameters array

#5

Hi Evgeny,

I tried the following and at first instance it seems to work:

procedure TDataService.DataAbstractServiceValidateDatasetAccess(Sender: TObject; const aConnection: IDAConnection;
const aDatasetName: string; const aParamNames: array of string; const aParamValues: array of Variant; aSchema: TDASchema;
var Allowed: Boolean);
var
i: integer;
DataSet: TDADataSet;
begin
DataSet := Schema.FindDataset(aDatasetName);

for i := Low(aParamNames) to High(aParamNames) do
begin
DataSet.Params.Add(aParamNames[i], aParamValues[i], TDADataType.datUnknown);
end;
end;

Freddy

#6

Hi,

if you manually add parameters to schema, it will work as expected