Django group options list











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1
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Using Django, I have the following working example to make a list with group option:



self.fields["crop"].choices = [( "First", ( ('1','aaa'), ('2','bbb'), ) ), ( "Second", ( ('3','ccc'), ) ), ]


First Method: I tried to make it dynamic using the hard way:



    sub_item =''
grouped_items=''

for k in Field.objects.filter(farm=farm):
print (k.field_name )
for o in Crop.objects.filter(farming_year=farming_year, field=k ):
sub_item = sub_item + '('+ str(o.id) + ',"' +o.crop_name + '"),'
grouped_items= grouped_items + '("' + k.field_name + '", (' + sub_item + ')),'
sub_item=''
full_list_items= '[' + grouped_items + ']'
print (full_list_items)
self.fields["crop"].choices = full_list_items
print(full_list_items )


I always get the following error:
not enough values to unpack (expected 2, got 1)



Second method: To test my code I copied the print(full_list_items )'s results from the terminal and assigned it directly to the crop list as shown below, and it works again!!!



self.fields["crop"].choices = [( "First", ( ('1','aaa'), ('2','bbb'), ) ), ( "Second", ( ('3','ccc'), ) ), ] 


the question here why I cannot get the required results when I use the first method and I did when I use the second one!!










share|improve this question


























    up vote
    1
    down vote

    favorite












    Using Django, I have the following working example to make a list with group option:



    self.fields["crop"].choices = [( "First", ( ('1','aaa'), ('2','bbb'), ) ), ( "Second", ( ('3','ccc'), ) ), ]


    First Method: I tried to make it dynamic using the hard way:



        sub_item =''
    grouped_items=''

    for k in Field.objects.filter(farm=farm):
    print (k.field_name )
    for o in Crop.objects.filter(farming_year=farming_year, field=k ):
    sub_item = sub_item + '('+ str(o.id) + ',"' +o.crop_name + '"),'
    grouped_items= grouped_items + '("' + k.field_name + '", (' + sub_item + ')),'
    sub_item=''
    full_list_items= '[' + grouped_items + ']'
    print (full_list_items)
    self.fields["crop"].choices = full_list_items
    print(full_list_items )


    I always get the following error:
    not enough values to unpack (expected 2, got 1)



    Second method: To test my code I copied the print(full_list_items )'s results from the terminal and assigned it directly to the crop list as shown below, and it works again!!!



    self.fields["crop"].choices = [( "First", ( ('1','aaa'), ('2','bbb'), ) ), ( "Second", ( ('3','ccc'), ) ), ] 


    the question here why I cannot get the required results when I use the first method and I did when I use the second one!!










    share|improve this question
























      up vote
      1
      down vote

      favorite









      up vote
      1
      down vote

      favorite











      Using Django, I have the following working example to make a list with group option:



      self.fields["crop"].choices = [( "First", ( ('1','aaa'), ('2','bbb'), ) ), ( "Second", ( ('3','ccc'), ) ), ]


      First Method: I tried to make it dynamic using the hard way:



          sub_item =''
      grouped_items=''

      for k in Field.objects.filter(farm=farm):
      print (k.field_name )
      for o in Crop.objects.filter(farming_year=farming_year, field=k ):
      sub_item = sub_item + '('+ str(o.id) + ',"' +o.crop_name + '"),'
      grouped_items= grouped_items + '("' + k.field_name + '", (' + sub_item + ')),'
      sub_item=''
      full_list_items= '[' + grouped_items + ']'
      print (full_list_items)
      self.fields["crop"].choices = full_list_items
      print(full_list_items )


      I always get the following error:
      not enough values to unpack (expected 2, got 1)



      Second method: To test my code I copied the print(full_list_items )'s results from the terminal and assigned it directly to the crop list as shown below, and it works again!!!



      self.fields["crop"].choices = [( "First", ( ('1','aaa'), ('2','bbb'), ) ), ( "Second", ( ('3','ccc'), ) ), ] 


      the question here why I cannot get the required results when I use the first method and I did when I use the second one!!










      share|improve this question













      Using Django, I have the following working example to make a list with group option:



      self.fields["crop"].choices = [( "First", ( ('1','aaa'), ('2','bbb'), ) ), ( "Second", ( ('3','ccc'), ) ), ]


      First Method: I tried to make it dynamic using the hard way:



          sub_item =''
      grouped_items=''

      for k in Field.objects.filter(farm=farm):
      print (k.field_name )
      for o in Crop.objects.filter(farming_year=farming_year, field=k ):
      sub_item = sub_item + '('+ str(o.id) + ',"' +o.crop_name + '"),'
      grouped_items= grouped_items + '("' + k.field_name + '", (' + sub_item + ')),'
      sub_item=''
      full_list_items= '[' + grouped_items + ']'
      print (full_list_items)
      self.fields["crop"].choices = full_list_items
      print(full_list_items )


      I always get the following error:
      not enough values to unpack (expected 2, got 1)



      Second method: To test my code I copied the print(full_list_items )'s results from the terminal and assigned it directly to the crop list as shown below, and it works again!!!



      self.fields["crop"].choices = [( "First", ( ('1','aaa'), ('2','bbb'), ) ), ( "Second", ( ('3','ccc'), ) ), ] 


      the question here why I cannot get the required results when I use the first method and I did when I use the second one!!







      python django






      share|improve this question













      share|improve this question











      share|improve this question




      share|improve this question










      asked Nov 12 at 8:55









      Yousef

      604




      604
























          1 Answer
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          oldest

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          up vote
          1
          down vote



          accepted










          You're building up a single string, not a list of tuples. I don't know why you are doing that. Instead of all this string concatenation, you should keep things as Python data structures:



          grouped_items = 
          for k in Field.objects.filter(farm=farm):
          sub_item =
          for o in Crop.objects.filter(farming_year=farming_year, field=k):
          sub_item.append((str(o.id), o.crop_name))
          grouped_items.append((k.field_name, sub_item))
          self.fields["crop"].choices = grouped_items


          Note that the inner loop could be rewritten as a list comprehension, and simplified further by using the reverse relation:



          sub_item = [(str(o.id), o.crop_name) for o in k.crop_set.filter(farming_year = farming_year)]





          share|improve this answer





















          • I used a list of tuples before and it gave me the same error, for sure I did mistake. Your answer works for me, Thanks
            – Yousef
            Nov 12 at 9:18











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          1 Answer
          1






          active

          oldest

          votes








          1 Answer
          1






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes








          up vote
          1
          down vote



          accepted










          You're building up a single string, not a list of tuples. I don't know why you are doing that. Instead of all this string concatenation, you should keep things as Python data structures:



          grouped_items = 
          for k in Field.objects.filter(farm=farm):
          sub_item =
          for o in Crop.objects.filter(farming_year=farming_year, field=k):
          sub_item.append((str(o.id), o.crop_name))
          grouped_items.append((k.field_name, sub_item))
          self.fields["crop"].choices = grouped_items


          Note that the inner loop could be rewritten as a list comprehension, and simplified further by using the reverse relation:



          sub_item = [(str(o.id), o.crop_name) for o in k.crop_set.filter(farming_year = farming_year)]





          share|improve this answer





















          • I used a list of tuples before and it gave me the same error, for sure I did mistake. Your answer works for me, Thanks
            – Yousef
            Nov 12 at 9:18















          up vote
          1
          down vote



          accepted










          You're building up a single string, not a list of tuples. I don't know why you are doing that. Instead of all this string concatenation, you should keep things as Python data structures:



          grouped_items = 
          for k in Field.objects.filter(farm=farm):
          sub_item =
          for o in Crop.objects.filter(farming_year=farming_year, field=k):
          sub_item.append((str(o.id), o.crop_name))
          grouped_items.append((k.field_name, sub_item))
          self.fields["crop"].choices = grouped_items


          Note that the inner loop could be rewritten as a list comprehension, and simplified further by using the reverse relation:



          sub_item = [(str(o.id), o.crop_name) for o in k.crop_set.filter(farming_year = farming_year)]





          share|improve this answer





















          • I used a list of tuples before and it gave me the same error, for sure I did mistake. Your answer works for me, Thanks
            – Yousef
            Nov 12 at 9:18













          up vote
          1
          down vote



          accepted







          up vote
          1
          down vote



          accepted






          You're building up a single string, not a list of tuples. I don't know why you are doing that. Instead of all this string concatenation, you should keep things as Python data structures:



          grouped_items = 
          for k in Field.objects.filter(farm=farm):
          sub_item =
          for o in Crop.objects.filter(farming_year=farming_year, field=k):
          sub_item.append((str(o.id), o.crop_name))
          grouped_items.append((k.field_name, sub_item))
          self.fields["crop"].choices = grouped_items


          Note that the inner loop could be rewritten as a list comprehension, and simplified further by using the reverse relation:



          sub_item = [(str(o.id), o.crop_name) for o in k.crop_set.filter(farming_year = farming_year)]





          share|improve this answer












          You're building up a single string, not a list of tuples. I don't know why you are doing that. Instead of all this string concatenation, you should keep things as Python data structures:



          grouped_items = 
          for k in Field.objects.filter(farm=farm):
          sub_item =
          for o in Crop.objects.filter(farming_year=farming_year, field=k):
          sub_item.append((str(o.id), o.crop_name))
          grouped_items.append((k.field_name, sub_item))
          self.fields["crop"].choices = grouped_items


          Note that the inner loop could be rewritten as a list comprehension, and simplified further by using the reverse relation:



          sub_item = [(str(o.id), o.crop_name) for o in k.crop_set.filter(farming_year = farming_year)]






          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered Nov 12 at 8:59









          Daniel Roseman

          442k41573629




          442k41573629












          • I used a list of tuples before and it gave me the same error, for sure I did mistake. Your answer works for me, Thanks
            – Yousef
            Nov 12 at 9:18


















          • I used a list of tuples before and it gave me the same error, for sure I did mistake. Your answer works for me, Thanks
            – Yousef
            Nov 12 at 9:18
















          I used a list of tuples before and it gave me the same error, for sure I did mistake. Your answer works for me, Thanks
          – Yousef
          Nov 12 at 9:18




          I used a list of tuples before and it gave me the same error, for sure I did mistake. Your answer works for me, Thanks
          – Yousef
          Nov 12 at 9:18


















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