I want to display hierarchical Data with a QML-Listview. This means that I have different Cpp datamodels, that have the following structure:
Section 1
Subsection 1
Item
Item
Subsection 2
Item
Section 2
The number of subsections is different in every model, so that I'm looking for a general solution to display that data in a flat list like that:
Section 1
Subsection 1
Item
Item
...
I'm using Qt 4.8.2 with Qt Quick 1.1.
What I figured out till now:
The QML ListView cannot display hierarchical listmodels
There are different solutions to display tree-structured extendable lists with multiple Listviews, but that's too complex for my models
I can make my model flat by using a Abstract-Class insert different Object types in a flat list, but that would be a lot of work, cause I had to insert lots of loops
Till now I found one solution provided by blackberry cascades, but I can't use it because I have to run my application on Embedded Linux:
Cascades Vegetables Data Model
At this moment I'm thinking about to write my own ListView with Cpp, but I would really like to avoid that because It will be a lot of work to implement that.
I'm new here at stackoverflow, so please let me know if I have to give you more informations.
Thank's in advance.
Quperman
EDIT 05.08.2014:
Temporary Solution:
Since It seems to be hard work for me to implement my own Cpp TreeView, I found another easier solution:
I created an abstract class AbstractItem with an attribute ItemType (enum), that has the following values:
Item
Section
Subsection
...
What I now do is the following:
I inherit my Section and Item classes from my new class AbstractItem. Now I put QList into my QAbstractListModel and appended the items, sections, subsections...
I can now provide different data in header and item by implementing the data() function with a switch over ItemType. depending on the ItemType I can do a reinterpret_cast to access the data.
Now I have a flat hierarchy that works for me. Sadly I can't use the class hierarchy, but at this moment it seems to be the fastest solution.
15th May 2015 We got beta version of Qt 5.5. See its features. Take a deep breath... Now you can use TreeView component in QML!
Take a look at snapshot for Qt 5.5 documentation.
Related
I am creating a Sitecore MVC site for a client and I need to create page that will list news articles for the company.
So far, I have created items that use a shared data template called “Article,” and I also have a sublayout (a view rendering) called “Article” that will display these items.
For the list itself, my plan was to create another component (a sublayout) call “News_List”, and to put a placeholder in it called “List”.
My question is this: can I allow the author to insert articles (e.g., N items of type “Article”) into this placeholder via the page editor?
Will SC allow you to insert multiple instances of the same component into a placeholder? Will this break anything?
I believe this is a pretty common question but I have not found a definitive answer. Thanks in advance…!
You can insert as many components (of the same type) in your placeholder as you want.. Just make sure to put the placeholder settings correctly and give it a decent name (not just "list" ;))
But are you sure you want to do this? Your editors will manually need to create a list of components for each article they want to add on the page. Doesn't sound to be very user (editor) friendly.. Maybe you should consider creating a list component that can get a list of articles as a datasource and show those. Or even select them automatically (but that might be not according to your business case)..
Yes, authors can add multiple instances of the same component into a single placeholder.
Assuming that the code of the component doesn't do any stupid things it's absolutely ok to do this.
Quite new to Sitecore and would like to understand the best way to access sitecore items. I've seen couple of ways:
Create Page ID field and get all items for given template and folder. Then do linq query on page ID.
Store all Page ID (Sitecore Item ID) on Constants file. Use this to query Sitecore using GetItem(itemID) API.
Could someone please suggest what's the best practice. Either way, I can see that there will be huge Constants file containing either custom Page ID or Sitecore Item ID.
My worry is do we really need to manage this Constants file or is there an elegant way to query CMS contents for given Page.
Thanks.
Approach 1 seems a bit odd. I don't really see why you would get a collection of items first when you already have the ID, but maybe I've misunderstood what you're saying.
I think a combination of 2 things you mention is best.
Constants classes are good for "landmark" items that will always definitely be there, so its fine for the GUID to be in code.
Some of these landmark items can be "configuraton items" that have fields containing the IDs of other items (These fields might have names like "Templates allowed in search"). This approach allows some flexibility for change by Sitecore users as the site evolves.
If you're concerned about the management of a constants file, I have to wonder how many items you need to access by ID. Sitecore items have properties like Parent and Children. You can also find items by template type etc.
This approach works well for me. I certainly don't think there is a more elegant way of getting strongly typed references to Sitecore items.
Personally, I prefer not to use constants files. What happens if your client or one of your developers deletes one of those items and creates a new one? One of the fundamental principles of Sitecore is that items can be added and removed by users who are not necessarily "technical" personnel.
Sitecore provides "Insert Options" so that you can specify what types of items can be added to each folder, and also grants the ability to protect certain items from deletion, via Roles and User Permissions. What does this mean conceptually? It means that Sitecore is set up such that the system architects/developers can create a structure that is not to be violated, while the content editors can add or remove content within that structure. In other words, Sitecore is designed to provide a framework in which the items can change but the location of each type of item is pre-determined.
As such, I suggest that you use the Custom Item Generator module available in the Sitecore Marketplace (free). CIG generates C# class representations (models) of your templates, and makes all fields into properties (I don't want to get too off-topic, but this is an awesome feature of CIG, especially when working with newer developers). You can add your own methods to your CIG classes for getting children of a particular type. For example, on a site in which the Profile Page is a direct child of the Homepage the following method could be added to the CIG HomepageItem.instance.cs file's HomepageItem partial class:
...
public partial class HomepageItem
{
public ProfilePageItem GetProfilePage()
{
//note that .IsOfType(...) is pseudo-code and not a real method, but I do
// suggest that you define an extension for it
return InnerItem.Children.FirstOrDefault(i => i.IsOfType(ProfilePageItem.TemplateId));
}
}
Be sure that you are assigning Insert Options to restrict the types of items that can be added as children to each item you make (add them on the Standard Values and not on the individual content items). I also suggest that you make a separate Template that inherits from Common/Folder for every folder that you use in the content tree. This way you can use CIG for your entire structure, via:
...in your Globals Item's CIG class...
public partial class GlobalsItem
{
public SlidesFolderItem GetSlidesFolder()
{
return InnerItem.Children.FirstOrDefault(i => i.IsOfType(SlidesFolderItem.TemplateId));
}
}
...in your Slides Folder Item's CIG class...
public partial class SlidesFolderItem
{
public IEnumerable<SlideItem> GetSlides()
{
return InnerItem.Children.Where(i => i.IsOfType(SlideItem.TemplateId));
}
}
and then you can get your Slide items via:
...
var slidesFolder = globals.GetSlidesFolder();
var slides = slidesFolder != null ? slidesFolder.GetSlides() : null;
Remember that CIG, Insert Options, and templates for each type of folder will enable you to create an iron-clad structure for your site that will not break if content editors make unexpected changes like replacing items.
Let me know if you have any questions on this. Good luck, and Happy Coding! :)
I'm currently working with the QCalendarWidget and I need some ideas to accomplish the following.
What would be the best way to add the selecteDate from a QCalendarWidget and a number to some sort of table. What I want is basically to have a list of dates with a number attached to each date, these numbers will be added together and the result will be displayed in a QLabel, I also want to be able to delete rows and again update the QLabel every time a row is deleted.
I also want to be able to save the list to an external file.
Should I use a QStringListModel or a QTableView?
How would you accomplish this?
I'm not expecting any code just a general procedure.
Please see the attached image for more details.
Should I use a QStringListModel or a QTableView?
You may want to familiarize yourself with the model/view framework. To put it simply, a model is the actual data that you have and it is independent of how it should be displayed. A view is a particular display implementation of a model. So you could use a model like the QStandarItemModel to store your String+number data and display the model in a QTableView.
Model/View Tutorial from Qt website here
QStandardItemModel class here. Has a simple example inside there.
And, for writing and reading the data to a file, I suggest you could use the QXmlStreamWriter/Reader classes. Refer to Qt xmlWriter/xmlReader
I've been reading about Qt's Model/View framework. I find it really helpful on working with tabled data like tables from a database. My question is: will it be useful for non-table data like property list or just some bunch of data of various types? If so, how should I approach it?
The goal is to come up with an editor for some property list like data. The list is constructed at runtime and the elements are of various types (numbers, strings, booleans, and file paths, to name a few). Each element is basically a name-value pair. The name, type, and restrains (limits for example) for each element are defined at compile time. They will be assembled at runtime into different lists depending on user input. And the list of elements can change during the edit session.
The UI will most likely be combination of various pre-designed widgets assembled according to user input. They may not be list or table views.
Some pointer to design pattern or examples are also much appreciated. Thanks.
I don't see a problem with MVC framework in QT for doing that.
Basically the difference between a standard table display and this is that you create a list dynamically akin to a map of:
QMap<QString, QVariant> property_map;
You can do a:
QList<std::pair<QString, QVariant>> property_list;
which you can then use to display in a table the property. The best way would probably be:
struct {
QString prop_name;
int prop_type;
QVariant prop_value;
};
QVariant basically will provide you with a single abstraction class for data storage and it is actually what's being returned by the data() function inside the QAbstractItemModel which you might be reimplementing.
So basically you will take a property list and boil it down to the same table like data as the database.
AMENDED
If you have a Widget that you want to have this widget populated with other predefined widgets you are quite likely to have multiple problems unless widgets are of same or well defined size.
What you can do is in you Display widget define a layout like: QGridLayout or other possible layouts and then add your other widgets to it using some set of parameters, which could be done but can be somewhat of a pain.
The other approach that you may take is to place all property widgets up front on the display UI and simply turn the ones you need on and the rest off, but this only applicable if you have a well defined limited number of pre-designed widgets.
I've been using Model/View framework for quite some time now and I usually implement my own models with a backend based on Qt containers (vectors, list, etc). Even if data eventually comes from a database, working with (e.g.) a vector of database ids can dramatically improve performance (and sometimes is the only way you can do).
This trivial example from Qt docs (see "Creating a Custom Model) is the point where I started and shows how to use a QStringList as a backend for a custom model.
Once defined your model you can define your custom Views, which will draw arranged widgets based on the content of the model underneath.
When the model change, your view will change accordingly rearranging widgets when necessary.
Leveraging QVariant capabilities you should be able to render the proper widget for every datatype (e.g. a QSpinBox for a float a QComboBox for a QStringList, and so on...)
First what I want: The ability to display a grid with multiple columns, each cell having a custom render callback. So you might use such a control to display your inventory in a game, or something like the behaviour in Google Chrome where it shows a grid of popular pages you visit.
I've been playing with CListCtrl and while I can get custom rendering ability on each item, I can't get it work with columns - having say 3 items per row. The control has column-related methods but I think these are specifically for the built-in functionality where different attributes of an item are shown automatically in each column... not for providing a generic grid control.
So, does such functionality exist in MFC? If not then I wonder if the easiest approach is for me to actually insert each of the rows as an Item... and then the custom rendering draws the multiple cells in the row, I could also do custom UI to support clicking on the cells.
But what I really want is to be able to create a custom control, and add this as an item to a list - like in Flex for instance - so I/O etc is automatically handled.
Any advice/information welcome...
Dundas has thrown some of its (excellent) components in the public domain. Their Ultimate Grid is available on CodeProject.
I'm not aware of a built-in control, but I think you should take a look at this.
The article is describing in detail the functionality of a fully featured MFC grid control, derived from CWnd, for displaying tabular data.
YOUR_LIST_CONTROL.SetExtendedStyle(LVS_EX_FULLROWSELECT|LVS_EX_INFOTIP|LVS_EX_GRIDLINES);
I think it will help you (SetExtendedStyle).
I suggest this one:
https://code.google.com/p/cgridlistctrlex/
very complete