[Qt-interest] display one database column as two in QTableView

[Israel Brewster]

On Mar 8, 2010, at 11:28 AM, André Somers wrote:

> Alternatively, you could create a proxy model that splits the date column
> into two separate columns. This would also work on databases that don't
> support editable queries.

I was thinking about something like that, but hadn't quite figured it out yet. If I'm thinking right, I would then need to override the data() and setData() functions to translate between the real model and proxy, and the columnCount function to return one additional column. Am I missing anything there? I'll give it a try here in a bit to see what happens. Thanks.

> 
> André
> 
> 
> -----Oorspronkelijk bericht-----
> Van: qt-interest-bounces at trolltech.com
> [mailto:qt-interest-bounces at trolltech.com] Namens Mark Brand
> Verzonden: maandag 8 maart 2010 20:32
> Aan: qt-interest at trolltech.com
> Onderwerp: Re: [Qt-interest] display one database column as two in
> QTableView
> 
> 
>> I have a database which contains a timestamp column. For editing
>> purposes, I want to display this as separate time and date columns. I
>> am using a QSqlTableModel, displayed with a QSqlTableView. How can I
>> make this happen?
>> 
>> My first thought was to subclass QSqlTableModel to expose the setQuery
>> function. I then passed a QSqlQuery like "SELECT
>> date(timestamp_column), time(timestamp_column) FROM table". This
>> worked to display the timestamp column as separate date and time
>> columns. However, when I edited the model and tried to save the
>> changes back to the database, I got a "syntax error around SET".
>> 
>> This might make sense, considering that the model now has two columns
>> whereas the database only has one, so I figured I'd simply override
>> the function that actually writes the data back to the database to
>> manually combine the date and time into a timestamp before submitting
>> the change to the database. It appears to me that the function I need
>> to override is updateRowInTable, but when I tried that it was
>> (apparently at least) never called. Is that the right function to be
>> using?
>> 
>> How can I display a timestamp column as separate date and time
>> columns, and keep it editable? Thanks.
>> 
> 
> I would make it easier on yourself.  One possibility is to use the
> QDateTimeEdit to edit the timestamp as a single column.
> 
> If you want to split it into 2 columns, I would recommend doing this in
> your database with a view (in the database sense, not the model/view
> sense) and a trigger to make the view updatable. If you do this right,
> you can treat the view like a plain old table in QSqlTableModel. There
> is one complication: You will almost certainly have to set the primary
> key in QSqlTableModel yourself since it won't be detected.
> 
> You're halfway there already:
> 
> CREATE VIEW my_view AS
>    SELECT date(timestamp_column) d, time(timestamp_column) t
>    FROM table
> 
> -Mark
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-----------------------------------------------
Israel Brewster
Computer Support Technician II
Era Alaska
5245 Airport Industrial Rd
Fairbanks, AK 99709
(907) 450-7250 x293
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