Flask is a lightweight WSGI web application framework. It is designed to make getting started quick and easy, with the ability to scale up to complex applications. Classified as a microframework, Flask is written in Python and it does not require particular tools or libraries. Let’s set up Postgres. NOTE: If you’re on a Mac, check out Postgres app. Once the local Postgres server is running, create two new databases from psql that share the same name as your project name. Step 3 — Create a Flask App. Now we are ready to move on to create a flask app. You can enter the following command to set up the project folder & the project environment.
Flask project in intended for productive development of the Flask applications. PyCharm takes care of creating the specific directory structure, and settings.
To create a Flask project, follow these steps
- From the main menu, choose File | New Project.., or click the New Project button in the Welcome screen. New Project dialog opens.
- In the New Project dialog, do the following:
- Specify project type Flask.
- Specify project location.
- Next, click to expand the Python Interpreter node, and select the new environment or existing interpreter, by clicking the corresponding radio-button.The following steps depend on your choice:
- New environment using: if this option has been selected, choose the tool to be used to create a virtual environment. To do that, click the list and choose Virtualenv , Pipenv , or Conda .Next, specify the Location and Base interpreter of the new virtual environment. If necessary, click the Inherit global site-packages and Make available to all projects check boxes.When configuring the base interpreter, you need to specify the path to the Python executable. If PyCharm detects no Python on your machine, it provides two options: to download the latest Python versions from python.org or to specify a path to the Python executable (in case of non-standard installation).
- Existing interpreter: if this option has been selected, choose the desired interpreter from the list, or (if the desired interpreter is not found), click and choose the interpreter. See Configure a Python interpreter for details.When PyCharm stops supporting any of the outdated Python versions, the corresponding Python interpreter is marked as unsupported.
- Click (More Settings), and specify the following:
- From the Template language list, select the language to be used.
- In the Templates folder field, specify the directory where the templates will be stored, and where they will be loaded from. You can specify the name of the directory that doesn't yet exist; in this case, the directory will be created.
- Click Create.
PyCharm creates an application and produces specific directory structure, which you can explore in the Project tool window. Besides that, PyCharm creates a stub Python script with the name app.py, which provides a simple 'Hello, World!' example.
You can run the created application by pressing Shift+F10 Preview the run results. Download saavn app for mac.
Note that the application was run with the following Flask specific variables:
![Set Flask App Mac Set Flask App Mac](/uploads/1/3/3/4/133401773/462561376.png)
FLASK_APP=app.py
– Defines an entry point of the Flask application - the target instance of theFlask
class. When extending your Flask application and adding more modules and files, you might need to pass some non-defaultFLASK_APP
values. You can pass a module name, a path to the target Python file, or any combination of modules, scripts, andFlask
class instances, for example,FLASK_APP=access_management.access:app2
, where:access_management
– the module nameaccess
– the target file in the moduleapp2
– theFlask
class instance inaccess
.
For more information about theFLASK_APP
variable, refer to Flask CLI documentation.FLASK_ENV=development
– Sets one of possible environments.FLASK_DEBUG=0
– Controls the built-in Flask debug mode. With this mode enabledFLASK_DEBUG=1
, the development server will be automatically reloaded on any code change enabling continuous debugging. For more information about Flask debugger, refer to Flask Debug Mode.
You can change Flask specific variables by editing the corresponding parameters of the Flask Server Run/Debug configuration.
When you've enabled Flask support in your project, the Python console starts acting as a Flask console. Use code completion to enter and execute Flask-specific commands.
- Flask Tutorial
- Flask Useful Resources
- Selected Reading
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In order to test Flask installation, type the following code in the editor as Hello.py
Importing flask module in the project is mandatory. An object of Flask class is our WSGI application.
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Flask constructor takes the name of current module (__name__) as argument.
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The route() function of the Flask class is a decorator, which tells the application which URL should call the associated function.
- The rule parameter represents URL binding with the function.
- The options is a list of parameters to be forwarded to the underlying Rule object.
![App App](/uploads/1/3/3/4/133401773/562549993.png)
In the above example, ‘/’ URL is bound with hello_world() function. Hence, when the home page of web server is opened in browser, the output of this function will be rendered.
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Finally the run() method of Flask class runs the application on the local development server.
All parameters are optional
Sr.No. | Parameters & Description |
---|---|
1 | host Hostname to listen on. Defaults to 127.0.0.1 (localhost). Set to ‘0.0.0.0’ to have server available externally |
2 | Defaults to 5000 |
3 | debug Defaults to false. If set to true, provides a debug information |
4 | options To be forwarded to underlying Werkzeug server. |
The above given Python script is executed from Python shell.
A message in Python shell informs you that
Mx simulator mac free download. Open the above URL (localhost:5000) in the browser. ‘Hello World’ message will be displayed on it.
Debug mode
A Flask application is started by calling the run() method. However, while the application is under development, it should be restarted manually for each change in the code. To avoid this inconvenience, enable debug support. The server will then reload itself if the code changes. It will also provide a useful debugger to track the errors if any, in the application.
The Debug mode is enabled by setting the debug property of the application object to True before running or passing the debug parameter to the run() method.