About variable scope. .. ..

Launch a local server using flask Output the ToDo task web application.

After that, when I arranged the template and executed flask run, the following error occurred.

app.py


UnboundLocalError: local variable 'count' referenced before assignment

Below is an excerpt of the part that caused the error

app.py


count = 0
@app.route("/updatedone/<int:item_id>")
def update_todoitemdone(item_id):
    todolist.update(item_id)
    count = count + 1
    return render_template("showtodo.html", todolist=todolist.get_all(), result=count)

The variable count declared outside the function If you want to use it in a function, you have to declare it globally.

Below, after correction.

app.py(Revised)


count = 0
@app.route("/updatedone/<int:item_id>")
def update_todoitemdone(item_id):
    todolist.update(item_id)
    global count
    count = count + 1
    return render_template("showtodo.html", todolist=todolist.get_all(), result=count)

Every time you press done, the number will be added! (('ω') ノ


↓ Reference article ↓ ToDo list app created with VS Code and Flask


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