[Qt-interest] QDataWidgetMapper and Custom Widget

[Robert Escott]

You most likely have functions that can read and set the value of custom 
widget with the value from the data model. If the type is QString, then 
it'll probably look something like this:
/
class CustomWidget : public QWidget{
public:
     //....
     QString value() const;
     void setValue(QString const &);
     // ...
};/

You would probably already have the following connections made for the 
QDataWidgetMapper:
/
QDataWidgetMapper mapper;
mapper.setModel(myModel);
mapper.addMapping(myWidget, 1); // Where 1 is the column in your model 
that contains the value for your custom widget/

If you have this kind of connection, the QDataWidgetMapper will be 
looking through the QMetaProperty list for properties that have the USER 
flag set and then updating that property with the data model's value. To 
create this property, you give it a type, a name, list it's accessor 
methods and then mark it as a user-facing property.

/class CustomWidget : public QWidget{
     Q_OBJECT
     Q_PROPERTY(QString value READ value WRITE setValue USER true)
public:
     //....
     QString value() const;
     void setValue(QString const &);
     // ...
};/

If you wish to map a property that is not a USER property, you use the 
alternative mapping function that names the property.

/mapper.addMapping(myWidget, 1, "value");/

Read up on "The Property System" in the documentation if you want more 
information.

On 01/05/2011 12:18, NaGeL wrote:
> thank you for the answer, and i read Q_property... but i dont quite 
> understand it how it works...or more like i don't really understand 
> whats its use, pourpuse.
>
> Could you explain it to me?
>
> 2011/4/30 Robert Escott <robert at binarylogic.co.za 
> <mailto:robert at binarylogic.co.za>>
>
>     Have a look in the documentation about Q_PROPERTY
>
>     If I remember correctly, QDataWidgetMapper will try and use the
>     data it gets from the model and set it to whatever property is set
>     as the USER property.
>
>
>     On 30/04/2011 00:24, NaGeL wrote:
>>     Hello? would somebody nice enough to reply me that this has been
>>     asked already,  or its a dumb question because Qt does this
>>     automatically, or no one did understand me?
>>
>>     2011/4/28 NaGeL <nagel182 at gmail.com <mailto:nagel182 at gmail.com>>
>>
>>         Hello!
>>         Newbie here.Also English isn't my native language, so sorry
>>         for any hiccups.
>>
>>         I'm currently doing a program that loads data from an SQL
>>         database, present it to the user, an d the user have the
>>         option to edit it...
>>
>>         never mind that.  I used QDatawidgetmapper to  map simple
>>         QLineEdits, and a Qcheckbox.
>>         This is all good, but there is a text field which requires a
>>         bigger field of text and needs to be presented to the user
>>         styled.(bold, italic crossed text etc.)
>>
>>         I figured I make a Custom Widget with QTextEdit and a toolbar
>>         that makes the styles, like a bold button, etc.
>>         and put the Custom Widget into the editor.
>>
>>         My question is: How can I use QDataWidgetMapper to map my
>>         custom Widget, and in that QTextEdit?
>>
>>         Also I would ask that QTextEdit  uses Html tags as style
>>         right? Is there a way to change that? using custom tags to
>>         style the text? I want to use something database lighter.
>>
>>         Again sorry if this sounds gibberish, English isn't my firts
>>         language, if this not understandable i will try to explain
>>         the whole situation in my next post.
>>
>>
>>
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