keep selected value in an html form, after submit

问题:

I have a simple form with a couple of select options. To illustrate it:

<form action="" method=GET>
    <select name="sort">
        <option value="name">name
        <option value="age">age
        <option value="gender">gender
        <option value="location">location
    </select>
    <input type="submit" value="sort">
</form>

Say that the user uses the form, selects gender and hits the submit button.

I sort the records based on user input ( in Django by the way ) and then I render the same page, but sorted as the user wanted.

My question: can I, somehow, keep in the form the selected value gender and not name, which is the first one?

回答1:

Pass the current sort field back to the template, then mark that option as selected as per the option docs: https://developer.mozilla.org/en/HTML/Element/option

<option value="name" {% if sort == 'name' %}selected{% endif %}>name</option>
<option value="age" {% if sort == 'age' %}selected{% endif %}>age</option>
<option value="gender" {% if sort == 'gender' %}selected{% endif %}>gender</option>
<option value="location" {% if sort == 'location' %}selected{% endif %}>location</option>

This would all be easier if you used the django forms framework.

class SortForm(forms.Form):
    sort = forms.ChoiceField(choices=[(x, x) for x in ['name', 'age', 'gender', 'location']])

def myview(request):
    form = SortForm(request.GET or None)
    # apply sort
    return render(request, "mytemplate.html", {'form': form})

{{ form.as_p }} # this would auto select whatever the form is bound with.