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sener · Guest

How can I pass the Blob field (BlobField.AsString) to
client by using CDS.DataRequest and Provider's OnDataRequest on
AppSrvr.

Clent
var Data: OleVariant;
Data := CDS.Request(..);
// the length of result string is wrong
// Cutted at first #0

AppSrvr
ProviderOnDataRequest(..): OleVariant;
// read somthing from SQLDataSet having BLOB field
Result := SQLdsBLOB_FIELD.AsString;
// Length is OK

thanks
Sener

Jaroslav Demin · Guest

Good morning/Evening!

I'm not sure if that's what you need.

1. Save value of blob field to stream;
TblobField(aField).SaveToStream(MemoryStream);

2. Convert Stream to Variant
procedure edllVarArrayToStream(const Data: OleVariant; Stream: TStream);
var
p: Pointer;
begin
p := variants.VarArrayLock(Data);
try
Stream.Write(p^, VarArrayHighBound(Data,1) + 1); //assuming low bound =
0
finally
VarArrayUnlock(Data);
end;
end;

function edllStreamToVarArray(Stream: TStream): OleVariant;
var
p: Pointer;
begin
Result := VarArrayCreate([0, Stream.Size - 1], varByte);
p := VarArrayLock(Result);
try
Stream.Position := 0; //start from beginning of stream
Stream.Read(p^, Stream.Size);
finally
VarArrayUnlock(Result);
end;
end;

3. Send it To client;

Hope, it was usefull

"sener" <sdemiral (AT) netscape (DOT) net> wrote