how to copy a ftBlob with firedac arrayDML

Question

I use Delphi Berlin.

I am trying to make a function/procedure to copy data from a FireDac query (connected to a database) to another FireDac query (connected to another database) using ArrayDML. first database is firebird and the other is MSSQL in the first care, but in another case both databases are Firebird.

So far so good and almost all datatype are working correct except ftBlob.

Here is the body of the function:

while not querySource.Eof do begin
  paramPosition := -1;
  Inc(mIndex);

  for i := 0 to querySource.FieldCount - 1 do begin
    Inc(paramPosition);
    // daca exista o valoare
    if querySource.FieldByName(querySource.Fields[i].FieldName).AsVariant <> Null then begin
      case querySource.Fields[i].DataType of
        ftDateTime, ftDate, ftTime, ftTimeStamp : queryInsert.Params[paramPosition].AsDateTimes[mIndex] := querySource.FieldByName(querySource.Fields[i].FieldName).AsDateTime;
        ftFloat, ftCurrency, ftBCD, ftFMTBcd    : queryInsert.Params[paramPosition].AsFloats[mIndex]    := querySource.FieldByName(querySource.Fields[i].FieldName).AsFloat;
        ftSmallint, ftInteger, ftLargeint       : queryInsert.Params[paramPosition].AsIntegers[mIndex]  := querySource.FieldByName(querySource.Fields[i].FieldName).AsInteger;
        ftString                                : queryInsert.Params[paramPosition].AsStrings[mIndex]   := querySource.FieldByName(querySource.Fields[i].FieldName).AsString;
        ftBlob, ftMemo, ftGraphic               : queryInsert.Params[paramPosition].AsBlobs[mIndex]     := querySource.FieldByName(querySource.Fields[i].FieldName).AsVariant;
      end;
    end;
  end;

the blob value is not copy the correct value from the source.

how to use the arrayDML in this case? any workaround?

Answer 1

I won't answer your question but suggest you to use the TFDBatchMove component because you are reinventing wheel here. TFDBatchMove is just for what you want to do, for moving data from one database to another (and not only that).

You simply setup the TFDBatchMoveSQLReader as Reader and Writer, write SQL queries for both and the component will automatically map the fields by matching names. If the queries won't have matching field names, you can fine tune this by the Mappings property. Then you just call Execute.