Delphi-如何在SQLite数据库中将位图保存到BLOB字段 [英] Delphi - How to save bitmap to BLOB field in SQLite database

问题描述

我试图将TBitmap图像数组添加到ClientDataSet的不同记录中(在ftBlob字段中)，然后将这些记录保存到SQLite数据库中. BLOB字段(DocImage)是数据库中的必填字段.

I am trying to add an array of TBitmap images to different records of a ClientDataSet (in a ftBlob field) and then save those records to a SQLite database. The BLOB field (DocImage) is a required field in the database.

但是，我的代码似乎根本没有将位图保存到ClientDataSet中的blob字段中.因此，当我调用BdmMain.cdsTrxDoc.ApplyUpdates(0)时，出现错误:字段'DocImage'必须具有一个值."

However, my code does not seem to save the bitmaps to the blob field in the ClientDataSet at all... So when I call BdmMain.cdsTrxDoc.ApplyUpdates(0), I get the error: "Field 'DocImage' must have a value."

在调用FTrxPhotoValue[i].SaveToStream(BlobStream)之前和之后，我已经检查了BlobStream(BlobStream.Size)的大小，并且确实增加了大小，但是BlobField的数据大小仍然为0.

I have checked the size of my BlobStream (BlobStream.Size) before and after calling FTrxPhotoValue[i].SaveToStream(BlobStream) and it does increase in size, but BlobField's data size remains 0.

以下是代码段:

FTrxIDValue: Integer;
FTrxDocIDValue: array of Integer;
FTrxPhotoValue: array of TBitmap;
// ...
for i := 0 to Length(FTrxPhotoValue) do
begin
  BdmMain.cdsTrxDoc.Insert;
  BdmMain.cdsTrxDoc['TrxID'] := FTrxIDValue;
  BdmMain.cdsTrxDoc['DocID'] := FTrxDocIDValue[i];
  BlobField := BdmMain.cdsTrxDoc.FieldByName('DocImage');
  BlobStream := BdmMain.cdsTrxDoc.CreateBlobStream(BlobField, bmWrite);
  FTrxPhotoValue[i].SaveToStream(BlobStream);
end;
// ...
BdmMain.cdsTrxDoc.ApplyUpdates(0);

推荐答案

调用SaveToStream后，应Free该流.该流仅在Destroy期间更新基础字段.

You should Free the stream after the call to SaveToStream. The stream will update the underlying field only during Destroy.

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