From 742c590a3a23f2d55ad9d70e1c6dd7685c57dbee Mon Sep 17 00:00:00 2001
From: lacak <lacak@idefix.freepascal.org>
Date: Tue, 11 Mar 2014 09:46:46 +0000
Subject: [PATCH] fcl-db: bufdataset: when data are written to BLOB field
 (using TBufBlobStream) then unset field null flag when blob stream is
 created. When writting finishes (on destroy of blob stream) set null flag if
 blob is empty. + updated test TestChangeBlob. Bug #15376

git-svn-id: trunk@27089 -
---
 packages/fcl-db/src/base/bufdataset.pas  | 30 ++++++++++--------------
 packages/fcl-db/tests/testfieldtypes.pas |  9 +++++--
 2 files changed, 20 insertions(+), 19 deletions(-)

diff --git a/packages/fcl-db/src/base/bufdataset.pas b/packages/fcl-db/src/base/bufdataset.pas
index 88321107d9..cc4edf01bf 100644
--- a/packages/fcl-db/src/base/bufdataset.pas
+++ b/packages/fcl-db/src/base/bufdataset.pas
@@ -2422,7 +2422,7 @@ procedure TCustomBufDataset.InternalCancel;
 Var i            : integer;
 
 begin
-  if assigned(FUpdateBlobBuffers) then for i:=0 to length(FUpdateBlobBuffers)-1 do
+  if assigned(FUpdateBlobBuffers) then for i:=0 to high(FUpdateBlobBuffers) do
     if assigned(FUpdateBlobBuffers[i]) and (FUpdateBlobBuffers[i]^.FieldNo>0) then
       FreeBlobBuffer(FUpdateBlobBuffers[i]);
 end;
@@ -2431,26 +2431,14 @@ procedure TCustomBufDataset.InternalPost;
 
 Var ABuff        : TRecordBuffer;
     i            : integer;
-    bufblob      : TBufBlobField;
-    NullMask     : pbyte;
     ABookmark    : PBufBookmark;
 
 begin
   inherited InternalPost;
 
-  if assigned(FUpdateBlobBuffers) then for i:=0 to length(FUpdateBlobBuffers)-1 do
+  if assigned(FUpdateBlobBuffers) then for i:=0 to high(FUpdateBlobBuffers) do
    if assigned(FUpdateBlobBuffers[i]) and (FUpdateBlobBuffers[i]^.FieldNo>0) then
-    begin
-    bufblob.BlobBuffer := FUpdateBlobBuffers[i];
-    NullMask := PByte(ActiveBuffer);
-
-    if bufblob.BlobBuffer^.Size = 0 then
-      SetFieldIsNull(NullMask, bufblob.BlobBuffer^.FieldNo-1)
-    else
-      unSetFieldIsNull(NullMask, bufblob.BlobBuffer^.FieldNo-1);
-
-    bufblob.BlobBuffer^.FieldNo := -1;
-    end;
+    FUpdateBlobBuffers[i]^.FieldNo := -1;
 
   if State = dsInsert then
     begin
@@ -2764,8 +2752,11 @@ begin
       else
         FBlobBuffer^.OrgBufID := -1;
       bufblob.BlobBuffer := FBlobBuffer;
-      // redirect pointer in current record buffer to new write blob buffer
+
       CurrBuff := GetCurrentBuffer;
+      // unset null flag for blob field
+      unSetFieldIsNull(PByte(CurrBuff), Field.FieldNo-1);
+      // redirect pointer in current record buffer to new write blob buffer
       inc(CurrBuff, FDataSet.FFieldBufPositions[Field.FieldNo-1]);
       Move(bufblob, CurrBuff^, FDataSet.GetFieldSize(FDataSet.FieldDefs[Field.FieldNo-1]));
       FModified := True;
@@ -2777,11 +2768,16 @@ begin
   if FModified then
     begin
     // if TBufBlobStream was requested, but no data was written, then Size = 0;
-    //  used by TBlobField.Clear, so in this case set Field to null in InternalPost
+    //  used by TBlobField.Clear, so in this case set Field to null
     //FField.Modified := True; // should be set to True, but TBlobField.Modified is never reset
 
     if not (FDataSet.State in [dsFilter, dsCalcFields, dsNewValue]) then
+      begin
+      if FBlobBuffer^.Size = 0 then // empty blob = IsNull
+        // blob stream should be destroyed while DataSet is in write state
+        SetFieldIsNull(PByte(FDataSet.GetCurrentBuffer), FField.FieldNo-1);
       FDataSet.DataEvent(deFieldChange, PtrInt(FField));
+      end;
     end;
   inherited Destroy;
 end;
diff --git a/packages/fcl-db/tests/testfieldtypes.pas b/packages/fcl-db/tests/testfieldtypes.pas
index 1cd421c22b..e17546a0f3 100644
--- a/packages/fcl-db/tests/testfieldtypes.pas
+++ b/packages/fcl-db/tests/testfieldtypes.pas
@@ -608,9 +608,7 @@ begin
 end;
 
 procedure TTestFieldTypes.TestChangeBlob;
-
 var s : string;
-
 begin
   TSQLDBConnector(DBConnector).Connection.ExecuteDirect('create table FPDEV2 (ID int,FT '+FieldtypeDefinitions[ftblob]+')');
   TSQLDBConnector(DBConnector).CommitDDL;
@@ -633,6 +631,13 @@ begin
     Cancel;
     AssertEquals('After Cancel', 'Test this blob', Fields[1].AsString); // original value
 
+    Append; // Blob is null
+    Fields[1].AsString := s; // Null flag must be unset
+    AssertEquals(s, Fields[1].AsString);
+    Fields[1].Clear;
+    AssertTrue('Clear', Fields[1].IsNull);
+    Cancel;
+
     Edit;
     With CreateBlobStream(Fields[1], bmWrite) do
       begin