Delphi 2010: How to save a whole record to a file?

As promised here it is: https://github.com/KrystianBigaj/kblib

When you defined for example record as:

TTestRecord = record
  I: Integer;
  D: Double;
  U: UnicodeString;
  W: WideString;
  A: AnsiString;
  Options: TKBDynamicOptions;

  IA: array[0..2] of Integer;

  AI: TIntegerDynArray;
  AD: TDoubleDynArray;
  AU: array of UnicodeString;
  AW: TWideStringDynArray;
  AA: array of AnsiString;

  R: array of TTestRecord; // record contain dynamic array of itself (D2009+)
end;

You can save whole dynamic record to stream (as binary data) by :

TKBDynamic.WriteTo(lStream, lTestRecord, TypeInfo(TTestRecord));

To load it back:

TKBDynamic.ReadFrom(lStream, lTestRecord, TypeInfo(TTestRecord));

It not need to be a record, you can do same for any dynamic type like:

TKBDynamic.WriteTo(lStream, lStr, TypeInfo(UnicodeString));
TKBDynamic.WriteTo(lStream, lInts, TypeInfo(TIntegerDynArray));
TKBDynamic.WriteTo(lStream, lArrayOfTestRecord, TypeInfo(TArrayOfTestRecord)); // TArrayOfTestRecord = array of TTestRecord;

Tested on Delphi 2006/2009/XE. License: MPL 1.1/GPL 2.0/LGPL 3.0 See readme for information.

You can load and save the memory of a record directly to and from a stream, as long as you don't use dynamic arrays. So if you use strings, you need to make them fixed:

type TTestRecord = record 
  FMyString : string[20]; 
end; 

var 
  rTestRecord: TTestRecord;
  strm : TMemoryStream; 

strm.Write(rTestRecord, Sizeof(TTestRecord) );

You can even load or save an array of record at once!

type TRecordArray = array of TTestRecord;

var ra : TRecordArray; 

strm.Write(ra[0], SizeOf(TTestRecord) * Length(ra));

In case you want to write dynamic content:

iCount   := Length(aArray);
strm.Write(iCount, Sizeof(iCount) );      //first write our length
strm.Write(aArray[0], SizeOf * iCount);   //then write content

After that, you can read it back:

strm.Read(iCount, Sizeof(iCount) );       //first read the length
SetLength(aArray, iCount);                //then alloc mem
strm.Read(aArray[0], SizeOf * iCount);    //then read content