CS50x threads to aide as a supplementary resource Forums CS50’s Introduction to Computer Science by Harvard University on Edx Week 9: Flask Understanding Flask routing and template rendering with query parameters

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    def index():
        name = request.args["name"]
        return render_template("index.html", placeholder=name)


    Understanding Flask Routing and Template Rendering with Query Parameters

    While I could perhaps understand that on the third line of the above code, name is a newly defined variable, not sure about [“name”] as part of request.args[“name”]. Does [“name”] refers to the name of a key named “name” that when will be put on the browser url after ? will lead to storing of the value of the key in a Python dictionary?

    So how does it relate to placeholder=name in the fourth and the last line? Whatever entered as part of {{placeholder}} in index.html gets allocated to name variable of the 3rd line that will next consider the same as value of the key named [“name”]?


    Yes, you’re on the right track! Let’s break it down:

    1. request.args is a dictionary-like object in Flask that contains the parsed contents of the query string in the URL. So, when you access request.args["name"], you’re indeed retrieving the value associated with the key “name” in the query string of the URL.
    2. In the URL, parameters are usually passed in the format ?key1=value1&key2=value2. For example, if your URL is http://example.com/?name=John`, thenrequest.args[“name”]` would return “John”.

    3. Now, let’s look at the render_template function. In Flask, this function is used to render HTML templates. When you call render_template("index.html", placeholder=name), you’re telling Flask to render the “index.html” template and pass the value of the name variable to it, which will be available in the template as {{ placeholder }}.

    4. In the “index.html” template, wherever you have {{ placeholder }}, it will be replaced with the value of the name variable. So, if name is “John”, then {{ placeholder }} will be “John”.

    So, essentially, whatever value is passed in the “name” parameter of the URL will be displayed in the HTML template at the placeholder position.

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