How to convert a Django QuerySet to a list

Question

I have the following   answers   Answer objects filter id  in  answer id for answer in answer set answers all       then later   for i in range len answers          iterate through all existing QuestionAnswer objects     for existing question answer in existing question answers            if an answer is already associated  remove it from the           list of answers to save         if answers i  id    existing question answer answer id              answers remove answers i               doesn t work             existing question answers remove existing question answer    I get an error    QuerySet  object has no attribute  remove    I ve tried all sorts to convert the QuerySet to a standard set or list  Nothing works   How can I remove an item from the QuerySet so it doesn t delete it from the database  and doesn t return a new QuerySet  since it s in a loop that won t work

User · Answer

Try this values list  column name   flat True     answers   Answer objects filter id  in  answer id for answer in answer set answers all     values list  column name   flat True    It will return you a list with specified column values

User · Answer

It is a little hard to follow what you are really trying to do   Your first statement looks like you may be fetching the same exact QuerySet of Answer objects twice   First via answer set answers all   and then again via  filter id  in        Double check in the shell and see if this will give you the list of answers you are looking for   answers   answer set answers all     Once you have that cleaned up so it is a little easier for you  and others working on the code  to read you might want to look into  exclude   and the   in field lookup     existing question answers   QuestionAnswer objects filter       new answers   answers exclude question answer  in existing question answers    The above lookup might not sync up with your model definitions but it will probably get you close enough to finish the job yourself   If you still need to get a list of id values then you want to play with  values list     In your case you will probably want to add the optional flat True   answers values list  id   flat True

User · Answer

instead of remove   you can use exclude   function to remove an object from the queryset  it s syntax is similar to filter   eg   - qs   qs exclude id  1   in above code it removes all objects from qs with id  1  additional info  - filter   used to select specific objects but exclude   used to remove

User · Answer

You could do this   import itertools  ids   set existing answer answer id for existing answer in existing question answers  answers   itertools ifilter lambda x  x id not in ids  answers    Read when QuerySets are evaluated and note that it is not good to load the whole result into memory  e g  via list      Reference  itertools ifilter  Update with regard to the comment   There are various ways to do this  One  which is probably not the best one in terms of memory and time  is to do exactly the same    answer ids   set answer id for answer in answers  existing question answers   filter lambda x  x answer id not in answers id  existing question answers

User · Answer

Why not just call   values  reqColumn1   reqColumn2   or  values list  reqColumn1   reqColumn2   on the queryset   answers list   models objects values  reqColumn1   reqColumn2    result      reqColumn1  value1  reqColumn2  value2    OR  answers list   models objects values list  reqColumn1   reqColumn2    result     value1 value2    You can able to do all the operation on this QuerySet  which you do for list

User · Answer

Why not just call list   on the Queryset   answers list   list answers    This will also evaluate the QuerySet run the query  You can then remove add from that list

User · Answer

By the use of slice operator with step parameter which would cause evaluation of the queryset and create a list   list of answers   answers   1    or initially you could have done   answers   Answer objects filter id  in  answer id for answer in         answer set answers all       1

User · Answer

def querySet to list qs               this will return python list lt dict gt              return  dict q  for q in qs   def get answer by something request       ss   Answer objects filter something  values       querySet to list ss    python list return  json-able    this code convert django queryset to python list

User · Answer

You can directly convert using the list keyword  For example   obj emp objects all   list1 list obj       Using the above code you can directly convert a query set result into a list    Here list is keyword and obj is result of query set and list1 is variable in that variable we are storing the converted result which in list

[django] How to convert a Django QuerySet to a list

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