At 5pm on Thursday afternoon, I completed the migration of the OP's management program with 354 units from ANSI Hebrew and dbExpress components to Unicode and FireDAC. When I write "completed", I mean that I had gone over every form and unit and replaced the dbExpress components with those of FireDAC. I also had briefly tested each form, but there was no guarantee that the program was free of bugs - in fact, I was fairly sure that the units that were first converted probably would not work correctly.
But before that, there was a topic that I had purposely not worked on, leaving it for the end. Almost all the forms that add data to the database have an autoincrement primary key; this is achieved by having a generator (something that returns a sequence of numbers, such as 1, 2, 3, ... 2001, 2002, etc) and a trigger that gets the next value from a generator and inserts it where needed. I didn't want functional generators when I was populating the new database from the old, but now that the translation had completed, I did need the generators and triggers for testing purposes.
What I really needed was to drop all the generators and triggers before transferring any data, then to recreate them after all the data had been transferred. CoPilot got the dropping code partially correct - it would work if there was a trigger but wouldn't if there was no trigger. Eventually CP developed some complicated SQL code for a conditional delete. This also had to be done in the correct order: first delete the trigger then the generator; this is because the trigger refers to the generate. Recreating the generators and triggers was easy, at least when done in the correct order. Then the generators had to be seeded with their new starting value. Originally I wrote a small query that would return the maximum value in the key field and used this, but then I noticed that the migrator calculates how many rows are in a table (for a progress bar) so I used this - and shortly discovered that the number of rows is not necessarily the highest value of the key; there might have been deletions from the table. Eventually that was fixed and I migrated the database once more.
On Saturday morning, I started working through the program and found some simple problems to fix, for example queries that weren't attached to the database connection. I found more queries whose fields needed to be redefined, and I found some that were wrong because the columns to which they were connected were not defined correctly. This required a fix to the database and remigration of a single table.
But there were some significant problems each of which took a few hours to fix. In what is probably the entire program's main form, the 'restore grid widths' routine wasn't working, although in fact, the correct values were returned but the grid 'ignored' them. The solution was to update the grid when all screen painting had finished, and so I added an OnPaint handler that sent a message to another procedure that would load the grid widths. This worked.
Another familiar problem occurred with a query called qSentReports: when certain reports are run, their HTML output is stored in a table so they can be retrieved at any stage. I had had problems when saving new reports in the table then restoring, so I assumed that retrieving reports that had been created in the previous version could be restored in a similar manner. But this was not so. According to CP, I was dealing with double or even triple encoding, involving WIN1255, WIN1252, UTF-16 and UTF-8. Then it struck me that the original data was already in UTF8 format, so the migrator shouldn't encode it and my code shouldn't decode it. After this epiphany, I once again transferred the data for this one table and finally it displayed correctly.
I am sure that there are further traps awaiting me, but I suspect that they will be minor. Now I don't know what to do with myself and all the free time that has suddenly opened up. 😉
| Title | Tags | ||
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| 1597 | Passover night, 2023 | Jewish holidays, Kibbutz | |
| 1920 | Slow cooked leg of lamb | Cooking, Slow cooker |
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