i read the documentation http://docs.wxwidgets.org/3.0/classwx_data_view_model.html several times but it hardly answers any questions. Maybe i'm confused as to the function of this class?
so i riddle you this:
Is this a View Model as we know from MVVM?
How do you implement a derivative?
How do you set data in the containing wxDataViewListCtrl?
Is this the right/recommended way to make a table?
As its name subtly hints, wxDataViewModel is indeed the model in the usual MVC design (while wxDataViewCtrl is both the view and the controller).
You can see a couple of examples of custom models in the dataview sample.
Notice that wxDataViewListCtrl is mostly a compatibility class made for transitioning the code using wxListCtrl to wxDataViewCtrl and it already defines its own trivial list model. I don't recommend using it unless this is exactly what you need.
Related
I'm looking for an easy way (I think there isn't) to serialize a QGraphicsView or QGraphicsScene into XML or JSON.
I don't know if I'm supposed to save the View or the Scene. XML or JSON are fine I only need one of them. I just want to save a scene in a file to save it/load it
I found few stuff on other websites but it's seems quite complicated, or not really functional.
First of all, check out this very useful tutorial for working with json. Secondly, I think I've read you're working with a model-view based project?
If so, all model info should be saved and then there are two possibilities (depending on your design). Let's say you have created a model class PlayerList and you are showing all players using a PlayerListLayout or PlayerListView, a derived class from QVBoxLayout. Now there are two possibilities:
In each of the view classes, you have a direct reference to the model class. Well, all you need is to ask the model using getters (these getters would exist already, else you don't want to visualize the information). You don't need the json file, as long as you initialize your model first. So, for the PlayerListLayout, all you need to do is ask each Player* of that PlayerList-member and call PlayerLayout::read(Player* player) on all PlayerLayout members of PlayerListLayout. PlayerLayout will initialize it's new player-reference and ask the name, the capital, etc. to visualize it.
In one of the view class, you have no reference to any model class. Then you shall have to pass either the model or the json file to that view class, so you can get/read the information (again). This is a less clean way, which I don't prefer. It happened to me that I was creating large functions to read; that's when I found out something had to change. Reading and writing should be easy (if you divide the responsibilities in multiple classes).
I've had a Monopoly project, where I used this serialization as well, and the tutorial was really helpful. Secondly, I opened the .json file outside the model class (so in the view class), which you might want to consider as well. The disadvantage is that "when you want wo re-use the model classes, but not the view classes", you shall have to reimplement the opening and closing of a file in your new gui.
However, this way you create parallelism throughout your code, because returning true/false will happen in the view class of the main model (MonopolyLayout in my case), so the methods Monopoly::read(...), Board::read(...) all behave in a similar way.
I had problem with saving relation to object with same class as parent.
You can check this problem here.
When I read that I can easily set the relationship after the promise has fulfilled here I created another example with that info in mind. But it doesn't work as I expect.
What I expect
Create array of Box instances with relation to previous Box instance in each.
And the question is if I'm doing something wrong or it's a bug. Let me know if you need any informations.
Your example isn't clear and simple enough. It needs to be isolated to EXACTLY what you're having an issue about and nothing else.
Having said that, I have had quite a bit of success saving relations to objects with the same class as parent, and so I don't think this is a problem with Ember Data or Ember.
Your code is quite convoluted and uses the sync library, which I'm not faimilar with.
It's a good idea to things as simply as possible at first, so try creating a jsbin with just the isolated functionality relating to saving relations that you're attempting, and then adding additional layers of functionality and testing after each add.
I am trying to implement a ProxyModel that takes a source Model that represents a flat, table like structure.
Then you can select one column of this model as a grouping value.
The proxy model should then create as many top nodes as there are distinct values of this column and sort the underlying rows into them.
But when doing this, is subclassing QAbstractProxyModel a viable option?
Since mapToSource(const QModelIndex& proxyIndex) will not always return a valid source index for a valid proxy index.
Does someone have a better solution, perhaps just using a QAbstractItemModel without the built in proxy functionality?
Here are two example projects which address this issue, for anyone's future reference. (One of them is mine, I do not mean to spam, it just seems relevant.)
GroupedItemsProxyModel (doc)
QGroupingProxyModel (doc)
Edit (response to comment): Both projects implement what, I believe, the question is asking about. I think examining the source provides the best examples and would obviously be too long to paste it all here. I've provided links directly to the source and to relevant documentation.
UPDATE: Sorry, understood this a little wrong. I never derived from abstract proxy model so I am not sure about that. However I would start using a QSortFilterProxyModel. It may happen that it has some functionality you do not need but this does not hurt. On the other hand implementing your on proxy model could hurt since it requires additional work and know-how.
If you should experience problems switching from the non-grouped structure to the grouped structure within the proxy model consider switching the model of the view (one showing grouped data, one showing original un-grouped data).
I've worked on multiple sites recently with similar content types but haven't gotten the design I'm looking to achieve.
I have multiple types of content article, interview, video, gallery, blog, etc. All of these models have very similar properties (title, slug, body, pub_date, etc). And since I'm using django and the admin, almost all the admin setting are identical as well. Most will only have one or two additional fields (ie. filename for video, author for blog).
Currents options are
Using single model "Post/Article" and then just have a type_of_content field. This gives me a single model which makes searches easier and faster and its easy to maintain one model. Managers could be used to pull certain types of content.
Have models 'Video, Interview, Audio' subclass a model called "Post/Article". Gains flexibility of working with different models without all the redundacy. Lots of joins though and all the admin code is still duplicated.
Be very redundant and create a separate model for each type of content even though they share the majority of fields. More stuff to maintain, not DRY at all but highest level of flexibility.
Any insight from someone with more experience would be great.
Thank you.
I don't have that much experience with Django, but it sounds like what you want to do is subclass off of an Abstract Base Class. This avoids creating a table for the abstract parent class, so you get the advantage of your option #2 without the need for joins.
I have a project with an FAQ app. The app has models for FAQ (written by the site authors) and UserFAQ (written by users-- not just a clever name). I want to return all entries, FAQ or UserFAQ that match certain conditions, but I also want to exclude any UserFAQs that don't match a certain criteria. Ideally, it would looks something like:
faqs = FAQ.objects.filter(question__icontains=search).exclude(show_on_site=False)
Where "show_on_site" is a property that only UserFAQ objects have. That doesn't work because the filter craps out on the parent class as it doesn't posses the property. What's the best way of doing this? I came across this snippet, but it seems like overkill for what I want to do.
In your position, absent a need to have two tables, I'd be tempted to have one FAQ model/table with is_user_faq and show_on_site fields.
Sometimes it helps when modeling data to organize it for simple and fast access. While model inheritance has some appeal, I've found it it's often easier to avoid using it.