Django check for any exists for a query

Question

In django how to check whether any entry exists for a query   sc scorm objects filter Header  id qp id    This was how it was done in php  if mysql num rows  resultn            True condition       else          False condition

User · Answer

As of Django 1 2  you can use exists     https   docs djangoproject com en dev ref models querysets  exists  if some queryset filter pk entity id  exists        print  Entry contained in queryset

User · Answer

this worked for me   if some queryset objects all   exists    print  quot this table is not empty quot

User · Answer

Use count     sc scorm objects filter Header  id qp id   if sc count    gt  0           The advantage over e g  len   is  that the QuerySet is not yet evaluated      count   performs a SELECT COUNT    behind the scenes  so you should always use count    rather than loading all of the record into Python objects and calling len    on the result    Having this in mind  When QuerySets are evaluated can be worth reading     If you use get    e g  scorm objects get pk someid   and the object does not exists  an ObjectDoesNotExist exception is raised   from django core exceptions import ObjectDoesNotExist try      sc   scorm objects get pk someid  except ObjectDoesNotExist      print       Update  it s also possible to use exists     if scorm objects filter Header  id qp id  exists                  Returns True if the QuerySet contains any results  and False if not  This tries to perform the query in the simplest and fastest way possible  but it does execute nearly the same query as a normal QuerySet query

[python] Django check for any exists for a query

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