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How to use a blob field to hold a record structure (Views: 101)


Problem/Question/Abstract:

I want to use a blob field to hold a record structure. ErrsTblErrs_Data has a blobType of "ftBlob"

type
  LogiRec = record
    LOGI_REG_NUM: array[1..9] of Char;
    LOGI_ENT_DATE: array[1..10] of Char;
    LOGI_Batch_num: array[1..6] of Char;
    LOGI_Trac_num: array[1..6] of Char;
    {...}
  end;

var
  Buffer: array[0..600] of char;
  Logi: LogiRec absolute Buffer;
  {...}
  {This works to get the data in}
  ErrsTblErrs_Data.asstring := Buffer;
  {This doesn't works to get the data out}
  Buffer := ErrsTblErrs_Data.asstring;

Is there a more elegant way of doing this?

Answer:

Try something like this to record the data:

var
  b: TBlobStream;
begin
  Table1.Append;
  b := TBlobStream.Create(Table1MyBlobField, bmWrite);
  try
    b.Write(MyRecord, sizeof(MyRecord));
  finally
    b.Free;
  end;
  Table1.Post;
end;

To read back:

var
  b: TBlobStream;
begin
  Table1.First;
  repeat
    begin
      b := TBlobStream.Create(Table1MyBlobField, bmRead);
      try
        b.seek(0, 0);
        b.Read(MyRecord, sizeof(MyRecord));
      finally
        b.Free;
      end;
    end;
  until Table1.EOF;
end;

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