Load data from Flask/Python to HTML textarea

I am trying to send data from Python / Flask to an HTML form textarea but need some help.

responses.html is shown below.

{% extends "layout.html" %}

{% block title %}
    Responses
{% endblock %}

{% block main %}

<form action="/responses" method="post">
    <div class="mb-3">
        <label for="response">Enter response here:</label><br>
        <input class="form-control mx-auto w-auto" autocomplete="off" id="response" name="response" placeholder="Enter your response here" type="textarea">
    </div>
    <button class="btn btn-primary" type="submit">Submit</button>
</form>
{% endblock %}

A portion of app.py is shown below:

@app.route("/responses", methods=["GET", "POST"])
@login_required
def responses():
    """Continue student application"""
    if request.method == "GET":
        user_id = session["user_id"]
        # check for existing data to supply the template. 
        responses = db.execute(
            "select * from extended_responses where user_id = ?",
            user_id)
        return render_template("responses.html", responses)
    # User reached route via POST
    if request.method == "POST":
        user_id = session["user_id"]
        # get form data
        response = request.form.get("response")
        # check if this is an update or new entry
        responses = db.execute(
            "select * from extended_responses where user_id = ?",
            user_id)
        if len(responses) > 0:
            # update answers
            db.execute("update extended_responses set user_id = ?, response = ? where user_id = ?", user_id, response, user_id)

        else:
            # insert answers
            db.execute("INSERT INTO extended_responses (user_id, response) VALUES (?, ?)", user_id, response)

I would like to display any previously recorded responses in the response textarea of responses.html while preserving the placeholder when no previous response was received from the user.

Answer

I suggest you replace input tag with textarea tag. Then you can add responses in textarea like this (p.s. you need to format responses, this example will just display SQL result):

<form action="/responses" method="post">
    <div class="mb-3">
        <label for="response">Enter response here:</label><br>
        <textarea 
            class="form-control mx-auto w-auto" 
            autocomplete="off" 
            id="response" 
            name="response" placeholder="Enter your response here"
        >{{responses}}</textarea>
    </div>
    <button class="btn btn-primary" type="submit">Submit</button>
</form>

If you still want to use input tag (although input type='textarea' is not valid HTML tag, you should switch to type='text') then you should add value attribute, like this:

<input ... type="text" value="{{responses}}"/>

Both approaches will populate the input/textarea with responses if there is any response, otherwise, it will show a placeholder

Also, I’ve noticed that you have an error in SQL code, you always replace the answer with the newest one so you’ll have just one answer in DB.