How to create a global variable for render

I have a simple task: to pass the same variable for different routes in the render_template() function. This value is in the base template and I need to pass it on every render_template() function. Can I set this value as a global value so that I don't have to set it in every function for different routes?

@app.route('/hello')
def hello(name=None):
    return render_template('hello.html', value=value)

@app.route('/bye')
def bye(name=None):
    return render_template('bye.html', value=value)```

CodePudding user response：

To make variables available to templates without having to burden your routes with passing those variables, use Flask context processors. See https://flask.palletsprojects.com/en/2.1.x/templating/#context-processors for details an an example.

Here's one that I use to 'cache bust' CSS so that browsers won't accidentally use stale versions.

style_css_path = os.path.join(os.path.dirname(__file__), 'static', 'style.css')
style_css_mtime = int(os.stat(style_css_path).st_mtime)

@app.context_processor
def cache_busters():
    return {
        'style_css_mtime': style_css_mtime,
    }

The base template can then do

<link rel="stylesheet"
      href="{{ url_for('static', filename='style.css') }}?v={{ style_css_mtime }}" />

Any template that uses base.html inherits this behavior without routes that use that template having to pass style_css_time.

CodePudding user response：

You could use a partial from functools like this:

from functools import partial

# Define a function that takes 2 parameters
def someFunc(a,b):
   print(f'Called with a:{a} and b:{b}')

# Define a "partial" where the parameters are partially pre-filled in
p1 = partial(someFunc, b="I was added for free")

# Now call the already partially defined function "p1"
p1("Hello")

Result

Called with a:Hello and b:I was added for free