Why is this many-to-many relation changing whitout me asking for it, using the Django ORM? -


i have recursive m2m relationship indicator class. indicator int, or calculated value 2 indicators:

class indicator(models.model):       params = models.manytomanyfield('self',                                  verbose_name=__(u'parameters'),                                 related_name='params_of',                                  blank=true, null=true)      type = models.charfield(max_length=64, verbose_name=__(u'type'))      def get_value(self, record):          # etc

according type, get_value doesn't same things. can return numerical value or calculate value numerical value of each parameters params attribute. can see params recursive m2m relationship.

now problem that, have follwoing indicators:

  • men
  • women
  • total pop
  • men ratio

if add men , women parameters of total pop, fine, , total pop dynamically calculated. if add men , total pop parameters men ratio, then total pop automatically men ratio parameter. breaks everything.

why that? how can avoid it?

m2m relations in django symmetric default ie in m2m, if related b b related a. stop this, use symmetrical=false

your params become:

params = models.manytomanyfield('self',                                  verbose_name=__(u'parameters'),                                 related_name='params_of',                                  blank=true, null=true,                                 symmetrical=false)

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