The ModelView Architecture QT S MVC-Like Interface for Displaying Data in Views

The Running App is Shown Below.

TODO 4+

For several years I used this application on my iPad, my iPhone and my MacBookPro. If it continues to work perfectly on iOS, it seems that it has not fully followed the evolution of MacOS.
No problems installing it. But it is no longer possible to synchronize with Toodledo on MacOS, while it continues to be possible on iOS: the same identifiers are not recognized.
It therefore becomes unnecessary for me … and the assistance of Appigo does not seem to be in a hurry to provide an answer to my request. It is always unpleasant to note that the concept of customer loses a little more of its value every day.

Pisa D

Since this update I have lost all my lists in the number of 12 and with which I work daily in a professional manner. I manage approximately 200 spots permanently, this update has put on the ground months of ordeal ! All the tasks organized in list found themselves grouped in a single global list. It is certainly not this bug that will make me pass to the version saying professional of this software otherwise excellent. I will never be captive. It only remains for me to wait for the response of the support contacted this evening by email or then find the old version of this magnificent software. I really hope that it is a youthful beug of the new version and not a strategy to force to migrate to the paid pro version to find functionalities already acquired with the previous version. For info my sync is done with dropbox

surlepoint, 12/13/2011

The synchro is now nickel

I grabbed before the synchronization which was slow, walked badly, etc. But now with iCloud, it suits me perfectly.

Some possible improvements: more display settings.
– to display only what the user uses. For example I do not use contexts or labels (in any case not yet) and I would like to no longer display these options which “pollute” my todo. I would like to have only “date / priority / list / type” for my everyday notes and right click for the options that I rarely use
– And conversely I would like a simple PLSU display than a drop -down menu to choose the date, priority, list, … if I have only three lists, then three buttons would be enough to be displayed, and I could choose My list with one click instead of clicking on the drop -down menu, find the name, and click on it. (ditto for priority, especially that we go from a very visual drawing on the todo list to a choice of name in the options which is not very natural.

These are ergonomics details. I like the simplicity and the efficiency of Todo, so I would like that it can be even more configurable to be even simpler.

Privacy app

The Developer, Appigo, has not provided details about its private practices and handling of data to apple. For more information, see the development’s privacy policy.

The ModelView Architecture
QT’s MVC-Like Interface for Displaying Data in Views

As you start to build more complex applications with pyqt5 you’ll likely come across keeping widgets in sync with your data. Data Stored in Widgets (e.g. a simple qlistwidget) is not readily available to manipulate from python – changes require you to get an item, get the data, and then set it back. The Default Solution to this is to Keep an External Data Representation in Python, and then Eith Duplicate Updates to the Both the Data and the Widget, OR SIMPLY REWRITE THE WIHOLE WIDGET FROM THE DATA. This can get ugly Quickly, and results in a lot of Boilerplate Just for Fiddling the Data.

Thankfully Qt has a solution for this – ModelViews. ModelViews are a powerful alternative to the Standard Display Widgets, which Use A Regular Model Interface to Interact with Data Sources – From Simple Data Structures to External Databases. This isolates your data, Allowing it to be kept in any structure you like, while the view Takes Care of Presentation and Updates.

This tutorial introduces the key aspects of Qt’s ModelView Architecture and Uses It to Build Simple Desktop Todo Application in Pyqt5.

Model View Controller

Model – See – Controller (MVC) is an architectural pattern use for development user interfaces that divids an application into three interconnected parts. This Separates the Internal Representation of Data from How Information is presented to and accept from the User.

The MVC Design Pattenn Fets Three Major Components –

• Model Holds the data structure which the app is working with.
• View is any representation of information as shown to the user, where graphical or table. Multiple views of the same data model are allowed.
• Control Accepts input from the user, transforming it into commands to for the model or view.

It qt land the distinction between the view & controller Gets a Little Murky. Qt Accepts input events from the User (via the OS) and Delegates these to the widgets (controller) to handle. However, Widgets also handle presentation of the Current State to the User, Putting Them Squarely in the view. Rather Than Agonize Over Where To Draw the Line, in Qt-S-Speak the View and Controller Are Ilead Merged Togd Toged A Model/ViewController Architecture-Called “Model View” for Simplicity Sake.

Importantly, the distinction between the data and How it is presented is preserved.

The Model View

The Model Acts as the interface between the data store and the viewcontroller. The Model Holds the Data (or a reference to it) and presents this data through a standardized api which views then consume and present to the user. Multiple views can share the same data, presenting it in completely different Ways.

You can use any “data store” for your model, included for example a standard python list or dictionary, or a database (via e.g. Sqlalchemy) – It’s entitirely up to you.

The two parts are essentially responsible for –

1. Tea model Stores the data, or a reference to it and returns individual or ranges of records, and associated metadata or display instructions.
2. Tea view Requests Data from the Model and Displays What is Returned on the Widget.

There is in-depth discussion of the qt architecture in the documentation.

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A simple model view – a todo list

To demonstrate How to Use the ModelViews in Practise, We’ll Put Together A very simple implementation of A Desktop Todo List. This will consist of a qlistview for the list of items, a qlineedit to enter new items, and a set of buttons to add, delete, or mark items as done.

The Ui

The simple ui was ugly outing qt creator and saved as mainwindow.ui . Tea .ui file and all the other parts can be downloaded below.

Designing a simple todo app in qt creator

The Running App is Shown Below.

The Running Todo Gui (Nothing Works Yet)

The widgets available in the interface we given the ids shown in the table below.

objeuch	Kind	Description
todview	Qlistview	The List of Current Todos
tododit	Qlineedit	The text input for creating a new todo item
addbutton	Qpushbutton	Create the New Todo, Adding It To The Todos List
deletebutton	Qpushbutton	Delete The Current Selected Todo, Removing It From the Todos List
Completebutton	Qpushbutton	Mark the Current Selected Todo As Done

We’ll use these identifiers to hook up the application logic later.

The Model

We define Our Custom Model by subclassing from Implementation, Allowing Us to Focus On The Parts Unique to Our Model. Qt Provids A Number of Different Model Bases, Including Lists, Trees and Tables (Ideal for Spreadsheets).

For this Example We Are Displaying The Result To A Qlistview . The matching base model for this is qabstractlistmodel . The Outline Definition for Our Model is Shown Below.

Class Todomodel (Qtcore.Qabstractlistmodel): Def __init __ (self, *args, todos = none, ** kwargs): super (todomodel, self).__init __ (*args, ** kwargs) Self.todos = todos or [] def data (self, index, role): if role == qt.Displayrole: # See Below for the Data Structure. status, text = self.Todos [Index.Row ()] # Return the Todo Text Only. Return Text Def Rowcount (self, index): Return Len (self.todos) 

Tea .Todos Variable is our data store and the Two Methods Rowcount () and Data () Are Standard Model Methods We must for a list Model. WE’LL go through these in turn below.

.Todos List

The Data Store for Our Model is .Todos, a simple python list in which we’ll store a tuple of values ​​in the format [(Bool, Str), (Bool, Str), (Bool, Str)] where Bool is the therefore state of a given entry, and str is the text of the todo.

We initialize self.TODO to an Empty List on Startup, Unless a List is Pass in via The Todos Keyword Argument.

self.todos = todos or [] will set self.todos to the provided todos value if it is truty (i.e. Anything Other Than An Empty List, the Boolean False or None The Default Value), otherwise it will be set to the empty list [] .

To create an insance of this model we can simple –

Model = Todomodel () # Create an Empty Todo List 

Or to pass in an existing list –

todos = [(false, 'an item'), (false, 'another item')] model = todomodel (todos) 

.Rowcount ()

Tea .ROWCOUNT () METHOD IS CALLADE BY THE VIEW TO GET THE NUMBER OF ROWS IN THE CURRENT DATA. This is required for the view to now the maximum index it can redo the data store (Row Count-1). Sale we using a python list as our data store, the Return Value for this is Simply the Len () of the list.

.Data ()

This is the Core of Your Model, Which Handles Requests for Data from the view and return the appropriate result. IT Receives Two Parameters Index and Role.

Index is the position/coordinates of the data that the view is requesting, accessible by Two Methods .Row () and .column () that give the position in each dimension.

For our qlistView the column is always 0 and can be ignored, but you would need to use this for 2d data in a spreadsheet view.

ROLE IS A FLAG INDICATING THE kind of data the view is requesting. This is because the .Data () METHOD ACTUALLY has more responsibility Than Just the Core Data. It also handles requests for style information, tooltips, status bars, etc. – Basalely Anything that could be informed by the data itself.

The Naming of Qt.Displayrole is a bit weird, but this indicates that the view is asking us “please give me data for display”. There are other roles Which the data can receive for styling Requests or Requesting Data in “Edit-Ready” Format.

Role	Value	Description
Qt.Display	0	The Key Data to Be Rendred in the Form of Text. (Qstring)
Qt.DecorationRole	1	The data to be rendered as a decoration in the form of an icon. (Qcolor, qicon or qpixmap)
Qt.Editorial	2	The data in a formal follow for editing in an editor. (Qstring)
Qt.TOOLTIPROLE	3	The Data Displayed in the item’s TOOLTIP. (Qstring)
Qt.Statustiprole	4	The Data Displayed in the Status Bar. (Qstring)
Qt.Whatsthisrole	5	The Data Displayed for the Item in “What’s this?” fashion. (Qstring)
Qt.Sizehintrole	13	The size hint for the item that will be supplied to views. (Qsize)

For a full list of available roles that you can receive see the qt itmdatarole documentation. Our todo list will only be using qt.Displayrole and qt.DecorationRole .

Basic implementation

Below is the basic stub application Needed to load the ui and display it. We’ll add our model code and application logic to this base.

Import Sys from Pyqt5 Import Qtcore, Qtgui, Qtwidgets, UIC from Pyqt5.Qtcore Import qt_creator_file = "Mainwindow.ui "ui_mainwindow, qtbaseclass = uic.LoaduDuype (qt_creator_file) class todomodel (qtcore.Qabstractlistmodel): Def __init __ (self, *args, todos = none, ** kwargs): super (todomodel, self).__init __ (*args, ** kwargs) Self.todos = todos or [] def data (self, index, role): if role == qt.Displayrole: status, text = self.Todos [Index.Row ()] Return Text Def Rowcount (Self, Index): Return Len (Self.Todos) Class Mainwindow (Qtwidgets.Qmainwindow, ui_mainwindow): def __init __ (self): Qtwidgets.Qumainwindow.__init __ (self) ui_mainwindow.__init __ (self) Self.Setupui (self) Self.Model = Todomodel () Self.todview.Setmodel (self.Model) App = Qtwidgets.Qapplication (sys.Argv) Window = Mainwindow () Window.Show () App.Exec_ () 

We define our todomodel as before, and initialize the Mainwindow Object. In the __init__ for the mainwindow we create an instance of our todo model and set this model on the todo_view . Save this file as todo.Py and run it with –

python3 todo.pace 

While there isn’t much to see yet, the qlistView and our model are actually working – if you add some default data you’ll see it appear in the list.

self.model = todomodel (todos = [(false, 'my first todo')]))) 

Qlistview showing hard-coded todo item

You can Keep Adding Items Manually Like this and they will show up in order in the qlistview . Next we’ll make it possible to add itms from within the application.

First Create a New Method on the Mainwindow Named Add . This is Our Callback Which Will Take Care of Adding the Current Text from the input as a new todo. Connect this method to the addbutton.Pressed Signal at the end of the __init__ block.

Class Mainwindow (Qtwidgets.Qmainwindow, ui_mainwindow): def __init __ (self): Qtwidgets.Qumainwindow.__init __ (self) ui_mainwindow.__init __ (self) Self.Setupui (self) Self.Model = Todomodel () Self.todview.Setmodel (self.Model) # Connect the Button. self.addbutton.press.Connect (self.Add) Def Add (self): "" Add an item to our todo list, getting the text from the qlineedit .TODOEDIT AND THERE CLEARING IT. "" "text = self.tododit.Text () If Text: # Don't Add Empty Strings. # Access the list via The Model. self.model.todos.Append ((false, text)) # trigger refresh. self.model.layoutchanged.Emit () # Empty the Input Self.tododit.Settext ("") 

In the Add Block Notice The Line Self.model.layoutchanged.Emit () . Here we emitting a model signal .layoutchanged to let the view Know that the shape of the data has been altered. This triggers a refresh of the entity of the view. If you omit this line, the todo will still be added but the qlistview won’t update.

If just the data is altered, but the number of rows/columns are unaffected you can use the .Datachanged () Signal INSTEAD. This also defines an altered region in the data using a top-left and bottom-right rental to avoid redrawing the whole view view.

Hooking up the other actions

We can now connect the rest of the button’s signals and add helpctions for performance delete and complete operations. We add the button signals to the __init__ block as before.

 self.addbutton.press.Connect (self.Add) Self.deletebutton.press.Connect (self.Delete) Self.Completebutton.press.Connect (self.Complete) 

Then Define a New Delete Method as follows –

 Def Delete (Self): Indexes = Self.todview.selectedDindexes () If indexes: # Indexes is a list of a single item in single-select. Index = Indexes [0] # Remove the item and refresh. Del Self.model.Todos [Index.Row ()] Self.model.layoutchanged.Emit () # Clear the selection (as it is no long valid). self.todview.CLARSELECTION () 

We use self.todview.selectedDindexes to get the Indexes (Actually a list of a single item, as we in single-selection mode) and then the .ROW () as an index Into our list of todos on our model. We Delete the Indexed Item Using Python’s Del Operator, and then Trigger A Layoutchanged Signal Because the Shape of the Data Has Been Modified.

Finallly, we clear the active selection since the item it relates to may now out of bounds (if you had selected the last item).

You could try make this smartter, and select the last item in the list instead

The Complete Method Likes Like This –

 Def Complete (self): Indexes = self.todview.selectredindexes () If indexes: index = indexes [0] ROW = index.Row () status, text = self.model.Todos [Row] Self.model.Todos [Row] = (True, Text) # .Datachanged Takes Top-Left and Bottom right, which are equal # for a single selection. self.model.datachanged.Emit (index, index) # Clear the selection (as it is no long valid). self.todview.CLARSELECTION () 

This Uses the Same Indexing As For Delete, But this Time We Fetch the Item from the Model .todos list and then replace the status with true .

We have to do this fetch-and-replacement, as our data is stored as python tuples which cannot be modified.

The Key Different here vs. Standard Qt widgets is that we make change directly to our data, and simplely need to notify Qt that changes haasurd – Updating the Widget State is handled automatically.

USING QT.DecorationRole

If you run the Application Now You Should Find That Adding and Deleting Both Work, But While Completing Items is working, there is no indication of it in the view. We need to update Our Model to Provide The View With An Indicator To Display when an item is complete. The Updated Model is Shown Below.

tick = qtgui.Qimage ('tick.png ') Class todomodel (qtcore.Qabstractlistmodel): Def __init __ (self, *args, todos = none, ** kwargs): super (todomodel, self).__init __ (*args, ** kwargs) Self.todos = todos or [] def data (self, index, role): if role == qt.Displayrole: _, text = self.Todos [Index.Row ()] Return text if role == qt.DecorationRole: status, _ = self.Todos [Index.Row ()] If status: Return Tick Def Rowcount (Self, Index): Return Len (Self.todos) 

Were using a tick icon tick.PNG to indicate complete items, which we load into a qimage object named tick . In the model we implemeted a handler for the qt.Decorationrole which Returns the Tick Icon for Rows Who’s Status is True (For Complete).

The icon i’m using is taken from the fugue set by p.yusukekamiyamane

INTOSTAD OF AN I icon you can also return to color, e.g. Qtgui.Qcolor (‘green’) which will be drawn as solid square.

Running the app you should now be able to mark items as complete.

Todos Marked Complete

A persist Data Store

Our todo app works nicely, but it has one fatal flaw-it forgets your todos as soon as you close the application While thinking you have Nothing to do when you do may to contribute to short-term feelings of zen, long term it’s probably a bad idea.

The solution is to implement some outing of persist data store. The Simplest Approach is a simple File Store, where we load items from a json or pickle file at startup, and write back on change.

To do this we define Two New Methods on our hand . These load data from a json file name data.JSON (if it exists, ignoring the error if it doesn’t) to self.model.Todos and Write the Current Self.model.Todos out to the same file, respectively.

 Def Load (self): Try: with open ('data.json ',' r ') as f: self.model.Todos = JSON.LOAD (F) Exception exception: PASS DEF SAVE (Self): With Open ('Data.json ',' w ') as f: data = json.DUMP (Self.model.todos, f) 

To persist the changes to the data we need to add the .Save () Handler to the End of Any Method that modifies the data, and the .Load () Handler to the __init__ block After the Model has been creating.

The final code looks like this –

Import Sys Import Json from Pyqt5 Import Qtcore, Qtgui, Qtwidgets, UIC from Pyqt5.Qtcore Import qt_creator_file = "Mainwindow.ui "ui_mainwindow, qtbaseclass = uic.LOADUDUSEYPE (qt_creator_file) tick = qtgui.Qimage ('tick.png ') Class todomodel (qtcore.Qabstractlistmodel): Def __init __ (self, *args, todos = none, ** kwargs): super (todomodel, self).__init __ (*args, ** kwargs) Self.todos = todos or [] def data (self, index, role): if role == qt.Displayrole: _, text = self.Todos [Index.Row ()] Return text if role == qt.DecorationRole: status, _ = self.Todos [Index.Row ()] If status: Return Tick Def Rowcount (Self, Index): Return Len (Self.Todos) Class Mainwindow (Qtwidgets.Qmainwindow, ui_mainwindow): Def __init __ (self): Super (Mainwindow, Self).__Init __ () Self.Setupui (self) Self.Model = Todomodel () Self.LOAD () Self.todview.Setmodel (self.Model) Self.addbutton.press.Connect (self.Add) Self.deletebutton.press.Connect (self.Delete) Self.Completebutton.press.Connect (self.Complete) Def Add (self): "" "Add an item to our todo list, Getting the text from the qlineedit .TODOEDIT AND THERE CLEARING IT. "" "text = self.tododit.Text () If Text: # Don't Add Empty Strings. # Access the list via The Model. self.model.todos.Append ((false, text)) # trigger refresh. self.model.layoutchanged.Emit () # Empty the Input Self.tododit.Settext ("") Self.Save () Def Delete (Self): Indexes = Self.todview.selectedDindexes () If indexes: # Indexes is a list of a single item in single-select. Index = Indexes [0] # Remove the item and refresh. Del Self.model.Todos [Index.Row ()] Self.model.layoutchanged.Emit () # Clear the selection (as it is no long valid). self.todview.CLARSELECTION () SELF.Save () Def Complete (Self): Indexes = Self.todview.selectredindexes () If indexes: index = indexes [0] ROW = index.Row () status, text = self.model.Todos [Row] Self.model.Todos [Row] = (True, Text) # .Datachanged Takes Top-Left and Bottom right, which are equal # for a single selection. self.model.datachanged.Emit (index, index) # Clear the selection (as it is no long valid). self.todview.CLARSELECTION () SELF.Save () Def Load (Self): Try: With Open ('Data.db ',' r ') as f: self.model.Todos = JSON.LOAD (F) Exception exception: PASS DEF SAVE (Self): With Open ('Data.db ',' w ') as f: data = json.DUMP (Self.model.todos, f) app = qtwidgets.Qapplication (sys.Argv) Window = Mainwindow () Window.Show () App.Exec_ () 

If the data in your application has the potential to get large or more complex, you may prefe to use an actual database to store it. In This Case The Model Will Wrap the Interface to the Database and Query It Directly for Data to Display. The l’ll cover How to do this in an upcoming tutorial.

For Another interesting Example of A Qlistview See this Example Media Player Application. It uses the qt building qmediaplaylist as the datastore, with the contents display to a qlistview .

About bcr.CX:

Bcr.CX is a Brazilian Technology Startup, Specialized in Both Both Business Outsourcing Processs (BPO) and Business Environment Outsourcing (BEO), Mainly Focused On Demand Generation, Customer Experience, Communication, User Support and Satisfaction.

Description:

The todo app was developed as a quick, safe, and user-friendly way to store the agent’s notes during the workdays.

Be Able to Create and Manage Your Own Tasks, Based on Each Individual Ticket or Customer.

Create Trails and Customize Your Workflow

Productivity enhance! Using todo app you can create customized workflows to standardize repeative processes. Try now and Start Controling Your Progress, as your todos and dones.

Resources:

1. CREATE TASKS FOR EACH TICKET
2. Progress bar to follow up deliverable
3. CREATE Standardized Workflows to Enhance Productivity.
4. Manage Your Task List, in order to keep it up with your Daily Routine.

1. Stack Both Todo and Zendesk Sunshine to obtain Full Access Over the App Features
2. Improve Productivity by Creating or Editing Tasks Automations, and Save Your Personalized Presets.