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Qt-interest Archive, March 2008
QTableView not allowing updates of records with NULL fields

Message 1 in thread

Hi,

I have a small application which is using a QTableView and a 
QSqlTableModel. On the backend I have a sqlite database.

The QSqlTableModel is created by doing the following SQL: create table 
IF NOT EXISTS foodlist (food text, units text, calories text)

Then, I insert a row into the table: insert into foodlist values  
('fooddata','100g', '100')

All pretty standard. I'm not connecting any slots or signals. Just 
creating the QSqlTableModel and passing it to the QTableView. I can see 
the data in the table without any problems.

But, suppose I do this instead: insert into foodlist values  
('fooddata',NULL,NULL)

The query succeeds, and the row is inserted. I can see the data in the 
QTableView. BUT when I edit the data, to change any or all of the three 
columns, the changes do not stick. The data in the database is not 
updated, and the table does show that.

I've tried connecting my own slot to the beforeUpdate signal on 
QSqlTableModel. Inside of that slot, I read the QSqlRecord and I can 
verify that the data I want written in the update is indeed present. 
But, it never gets updated on the disk.

Am I doing something obviously wrong?

Thanks.




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Message 2 in thread

You need to have a primary key column.


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Message 3 in thread

Acenes wrote:
> You need to have a primary key column.
>
>   
That's led me to another problem. I added a column to the table, of type 
"id integer primary key autoincrement". I am also hiding that column so 
it's not displayed.

When I try to edit the table, it says "QSqlQuery::value: not positioned 
on a valid record"

If I were executing a query, I'd do a next() to get to a result record. 
But, I'm updating by editing the QTableView attached to the model. Isn't 
the model supposed to take care of this?

Thanks,


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Message 4 in thread

> "id integer primary key autoincrement". I am also hiding that column so 
> it's not displayed.

> When I try to edit the table, it says "QSqlQuery::value: not positioned 
> on a valid record"

Hiding the primary key column from the view should work.
But I suppose you removed the column from the model instead.

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Message 5 in thread

Acenes wrote:
> Hiding the primary key column from the view should work.
> But I suppose you removed the column from the model instead.
>   

Wow you're good. Both of your replies were exactly right. Thank you for 
helping me out.


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