TvPlanIt: Improved handling of Firebird AutoInc field in ZEOS datastore.

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@8258 8e941d3f-bd1b-0410-a28a-d453659cc2b4

components/tvplanit/examples/datastores/zeos/unit1.pas

@@ -4,8 +4,8 @@ unit Unit1;
 
 // Activate ONE of the following defines for the database system to be used:
 
-{$DEFINE sqlite3}
+{.$DEFINE sqlite3}
-{.$DEFINE firebird3}
+{$DEFINE firebird3}
 
 interface
 

components/tvplanit/source/addons/zeos/vpzeosds.pas

@@ -20,6 +20,7 @@ type
     FEventsTable: TZTable;
     FResourceTable: TZTable;
     FTasksTable: TZTable;
+    procedure CreateAutoInc_Firebird(ATableName, AIdFieldName: String);
     procedure SetConnection(const AValue: TZConnection);
     
   protected
@@ -126,8 +127,8 @@ begin
     protocol := Lowercase(FConnection.Protocol);
     if protocol = 'firebird' then
     begin
-      FIdFieldTypeNameInSQL := 'INTEGER GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY';    // This is for Firebird v3
+//      FIdFieldTypeNameInSQL := 'INTEGER GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY';    // This can be used in Firebird v3 to replace the trigger and generator
-//      FIdFieldTypeNameInSQL := 'INTEGER NOT NULL PRIMARY KEY';    // This might work for firebird v2.x
+      FIdFieldTypeNameInSQL := 'INTEGER NOT NULL PRIMARY KEY';    // This works for firebird v2.x and v3 when triggers & generators are provided
       FBoolFieldTypenameInSQL := 'BOOLEAN';
     end else
     if protocol = 'postgresql' then
@@ -166,6 +167,27 @@ begin
   end;
 end;
 
+{ Create generator and trigger for Firebird in order to autoincrement the values
+  in field AIdFieldName of table ATableName.
+  http://firebirdfaq.org/faq29/ }
+procedure TVpZeosDatastore.CreateAutoInc_Firebird(ATableName, AIdFieldName: String);
+begin
+  FConnection.ExecuteDirect(Format(
+    'CREATE GENERATOR gen_%s_id;', [ATableName]
+  ));
+  FConnection.ExecuteDirect(Format(
+    'SET GENERATOR gen_%s_id TO 0;', [ATableName]
+  ));
+  FConnection.ExecuteDirect(Format(
+    'CREATE TRIGGER %0:s_BI FOR %0:s ' +
+    'ACTIVE BEFORE INSERT POSITION 0 ' +
+    'AS ' +
+    'BEGIN ' +
+    'if (NEW.%1:s is NULL) then NEW.%1:s = GEN_ID(GEN_%0:s_ID, 1); ' +
+    'END', [ATableName, AIdFieldName]
+  ));
+end;
+
 procedure TVpZeosDatastore.CreateTable(const ATableName: String;
   CreateIndex: Boolean = true);
 var
@@ -249,6 +271,8 @@ begin
         'CREATE INDEX ContactsCompany_idx ON Contacts(Company)'
       );
     end;
+    if Lowercase(FConnection.Protocol) = 'firebird' then
+      CreateAutoInc_Firebird('Contacts', 'RecordID');
   end else
   if ATableName = EventsTableName then begin
     FConnection.ExecuteDirect(
@@ -292,6 +316,8 @@ begin
         'CREATE INDEX EventsEndTime_idx ON Events(EndTime)'
       );
     end;
+    if Lowercase(FConnection.Protocol) = 'firebird' then
+      CreateAutoInc_Firebird('Events', 'RecordID');
   end else
   if ATableName = ResourceTableName then begin
     FConnection.ExecuteDirect(
@@ -312,6 +338,8 @@ begin
          'UserField8 VARCHAR(100), '+
          'UserField9 VARCHAR(100) )'
     );
+    if Lowercase(FConnection.Protocol) = 'firebird' then
+      CreateAutoInc_Firebird('Resources', 'ResourceID');
   end else
   if ATableName = TasksTableName then begin
     FConnection.ExecuteDirect(
@@ -347,6 +375,8 @@ begin
       FConnection.ExecuteDirect(
         'CREATE INDEX TasksCompletedOn_idx ON Tasks(CompletedOn)'
       );
+      if Lowercase(FConnection.Protocol) = 'firebird' then
+        CreateAutoInc_Firebird('Tasks', 'RecordID');
     end;
   end;
 end;
@@ -463,12 +493,7 @@ end;
   autoincrement fields. }
 function TVpZeosDatastore.GetNextID(TableName: string): integer;
 begin
-  {
+  Result := -1;
-  if (FConnection.Protocol = 'firebird') then     // Optionally use this for firebird 2.x
-    Result := random(maxInt)
-  else
-  }
-    Result := -1;
 end;
 
 function TVpZeosDatastore.GetResourceTable : TDataset;