Why this Django error "Too Many Values to Unpack"?

Question

I have a Django view that I'm calling via an Ajax function in a template. My template has a 'Country' pulldown and a 'Region' (or State) pulldown. When the user clicks on a Country, I want to use an Ajax function to fetch all the regions (or states) in that country and populate a 'Region' dropdown with that data. However, when my view executes and tries to return the query set, I'm getting this error:

ValueError: too many values to unpack

Here is the template tag and Ajax function:

# demo.html
<select id="id_country" name="country" onchange="getState(this.value);">
  <option value="" selected="selected">Please choose...</option>
  <option value="US">United States</option>
  <option value="GB">United Kingdom</option>
  <option value="CA">Canada</option>
</select>

<script>
function getState(val) {
    $.ajax({
    type: "GET",
    url: "/demo/get_region",
    data:'country_id='+val,
    success: function(data){
         $("#id_region").html(data);
    }
    });
}
</script>

Here is the view:

# views.py
from location.models import CountryRegion
def get_region(request):
    country_id = request.GET.get('country_id', None)
    country_region = CountryRegion.objects.filter(country_cd=country_id)
    # Error occurs here on the return
    return country_region

The model (which I realize isn't normalized) looks like this:

class CountryRegion(models.Model):
    country_cd = models.CharField(max_length=2)
    country_name = models.CharField(max_length=50)
    region_cd = models.CharField(max_length=3)
    region_name = models.CharField(max_length=50)

A database record looks like this:

id    country_cd    country_name    region_cd   region_name
59    US            United States   NY          New York

Why is this error occurring? If the country code is 'US', I would be returning 50 instances, one for each state. Is there some limit to the amount of data a Django view can return?

Possible duplicate of [Django view returning json without using template](http://stackoverflow.com/questions/9262278/django-view-returning-json-without-using-template) — Jed Fox, Jan 06 '17 at 22:28
You should return a `Response` object not a `CountryRegion` object. See https://docs.djangoproject.com/en/1.10/topics/http/views/ — Gocht, Jan 06 '17 at 22:35

score 0 · Answer 1 · answered Jan 09 '17 at 05:23

0

you have to import json first,
import json
then
return HttpResponse( json.dumps(country_region), content_type="application/json" )

answered Jan 09 '17 at 05:23

rsb

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Why this Django error "Too Many Values to Unpack"?

1 Answers1