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148 lines
3.1 KiB
Markdown
148 lines
3.1 KiB
Markdown
# Flask
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```python
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from flask import Flask, render_template
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app = Flask(__name__, template_folder="path_to_folder") # create app
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# template folder contains html pages
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@app.route("/") # define URLs
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def index():
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return render_template("index.html") # parse HTML page and return it
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if __name__ == "__main__":
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# run server if server is single file
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app.run(debug=True, host="0.0.0.0")
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```
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`@app.route("/page/")` enables to access the page with `url/page` and `url/page/`. The same is possible using `app.add_url_rule("/", "page", function)`.
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## Variable Rules
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You can add variable sections to a URL by marking sections with `<variable_name>`.
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Your function then receives the `<variable_name>` as a keyword argument.
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Optionally, you can use a converter to specify the type of the argument like `<converter:variable_name>`.
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Converter Type | Accepts
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---------------|------------------------------
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`string` | any text without a slash (default option)
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`int` | positive integers
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`float` | positive floating point values
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`path` | strings with slashes
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`uuid` | UUID strings
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```python
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@app.route("/user/<string:username>") # handle URL at runtime
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def profile(username):
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return f"{escape(username)}'s profile'"
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```
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## Redirection
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`url_for(endpoint, **values)` is used to redirect passing keyworded arguments. It can be used in combination with `@app.route("/<value>")` to accept the passed arguments.
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```py
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from flask import Flask, redirect, url_for
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@app.route("/url")
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def func():
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return redirect(url_for("html_file/function")) # redirect to other page
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```
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## Jinja Template Rendering (Parsing Python Code in HTML, CSS)
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* `{% ... %}` for **Statements**
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* `{{ ... }}` for **Expressions** to print to the template output
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* `{# ... #}` for **Comments** not included in the template output
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* `# ... ##` for **Line Statements**
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Use `{% block block_code %}` to put a line python code inside HTML.
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Use `{% end<block> %}` to end a block of code.
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In `page.html`;
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```py
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<html>
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{% for item in content %}
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<p>{{item}}</p>
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{% endfor %}
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</html>
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```
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In `file.py`:
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```py
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@app.route("/page/)
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def func():
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return render_template("page.html", content=["A", "B", "C"])
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```
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### Hyperlinks
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In `file.py`:
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```py
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@app.route('/linked_page/')
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def cool_form():
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return render_template('linked_page.html')
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```
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In `page.html`:
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```html
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<!doctype html>
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<html>
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<head>
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</head>
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<body>
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<a href="{{ url_for('linked_page') }}">link text</a>
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</body>
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</html>
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```
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### CSS
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Put `style.css` inside `/static/style`.
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In `page.html`:
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```html
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<!doctype html>
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<html>
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<head>
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</head>
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<link rel="stylesheet" href="{{ url_for('static', filename='style/style.css') }}">
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<body>
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</body>
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</html>
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```
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## Template Inheritance
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In `parent_template.html`:
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```html
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<html>
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<!-- html content -->
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{% block block_name %}
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{% endblock %}
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<!-- html content -->
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</html>
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```
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The content of the block will be filled by the child class.
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In `child_template.html`:
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```html
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{% extends "parent_template.html" %}
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{% block block_name}
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{{ super() }} <!-- use parent's contents -->
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<!-- block content -->
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{% endblock %}
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```
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