How to create a QGIS plugin in Python?

How to create a QGIS plugin in Python?

Since QGIS is using Python 2.7, subdirectories of these paths have to contain an __init__.py file to be considered Python packages that can be imported as plugins. By setting QGIS_PLUGINPATH to an existing directory path, you can add this path to the list of paths that are searched for plugins.

Is there a difference between QGIS and Python?

There is a confusion among QGIS, ArcGIS (or GRASS GIS, or..) users. These programs use Python for scripting but they are not Python. For example, QGIS uses Python in the console with the Python module qgis and plugins written in Python.

How to populate combo box with layers loaded in QGIS?

Let’s add some logic to the plugin that will populate the combo box with the layers loaded in QGIS. Go to the plugin directory and load the file save_attributes.py in a text editor. Scroll down and find the run (self) method. This method will be called when you click the toolbar button or select the plugin menu item.

How to ask your own question in pyqgis?

Asking for help, clarification, or responding to other answers. Making statements based on opinion; back them up with references or personal experience. To learn more, see our tips on writing great answers. Not the answer you’re looking for? Browse other questions tagged qgis pyqgis qgis-processing or ask your own question.

How to write new processing algorithms in QGIS?

Within QGIS, you can use Create new script in the Scripts menu at the top of the Processing Toolbox to open the Processing Script Editor where you can write your code. To simplify the task, you can start with a script template by using Create new script from template from the same menu.

Where do I Enter my Password to launch QGIS?

Click the Lock icon and enter your password. Click the Open Anyway button to launch QGIS. This step needs to be done only once. The next time, you can launch QGIS-LTR directly from the Applications folder. The code examples in this class use a variety of datasets.

How to print hello world in QGIS Python?

QGIS Comes with a built-in Python Console and a code editor where you can write and run Python code. Go to Plugins → Python Console to open the console. At the >>> prompt, type in the following command and press Enter. print(‘Hello World!’) Here you are running Python’s print () function with the text ‘Hello World’.

Why is QGIS 2.14 in a feature freeze?

Essen was the host city to our developer meet ups in October 2012 and 2014. This is a special release since it is designated an ‘LTR’ (Long Term Release). LTR releases will be supported with backported bug fixes for one year, and will be in permanent feature freeze (i.e. no new features will be added, only bug fixes and trivial updates).

Do you need to quit submenu in Python?

This worked and data created in the submenu (subchoice) can be used in the mainMenu options 3 & 4. You don´t need a “Quit” option in your submenu – you want to repeat the nested loop (the submenu) only in the case of wrong answer (other as 1, 2, 3 or 4).

What is the changelog for QGIS 2.14?

QGIS 2.14 has gained finer control over the placement of north arrows, scale bars and copyright notices on the main map canvas. You can now precisely set the position of these elements using a variety of units (including millimeters, pixels and percent).

Open QGIS. Go to Plugins ‣ Plugin Builder ‣ Plugin Builder. You will see the QGIS Plugin Builder dialog with a form. You can fill the form with details relating to our plugin. The Class name will be the name of the Python Class containing the logic of the plugin.

How to reload a processing plugin in QGIS?

Go to Plugin ‣ Plugin Reloader ‣ Choose a plugin to be reloaded. Select save_attributes_processing in the Configure Plugin reloader dialog. Click the Reload plugin button to load the latest version of the plugin. To test this new functionality, we must load some layers in QGIS.

How to set a breakpoint for a QGIS plugin?

So start QGIS in case you did not already and click the bug symbol. Now you can set a breakpoint and as soon as the code hits it, execution will stop and you can inspect the current state of your plugin.

Which is the best way to write a plugin in Python?

Some plugins are convenient when writing Python plugins. From Plugins ► Manage and Install plugins…, install: Plugin reloader: This will let you reload a plugin and pull new changes without restarting QGIS. First Aid: This will add a Python console and local debugger to inspect variables when an exception is raised from a plugin.

How to use custom expression functions in QGIS?

Download the simple (less columns) dataset Locate the ne_10m_populated_places_simple.zip file in the QGIS Browser and expand it. Select the ne_10m_populated_places_simple.shp file and drag it to the canvas. Go to Edit ‣ Select ‣ Select Features By Expression… or click the Select features using an expression button on the Attributes Toolbar.

How to create custom feature forms in QGIS?

Jump back into QGIS, load the properties dialog for the layer. Select the General tab and set Edit UI to the new form .ui file. Setting the edit form UI file. Save and exit the properties window. Enable the layer for editing (or not) and select an object with the Identify Feature tool.

How to access active layer of QGIS in Python?

Open it from Plugins > Python console or use the shortcut Ctrl+Alt+P on your keyboard. By default an iface object is imported, which allows the access to the currently active QGIS instance’s user interface. For example, we can easily retrieve the active (selected) layer, then access its type, name, and count its features: