  
  @ArrayField.register_lookup
  class ArrayLenTransform(Transform):
      lookup_name = 'len'
  
      @property
      def output_field(self):
          return IntegerField()
  
      def as_sql(self, compiler, connection):
          lhs, params = compiler.compile(self.lhs)
          return 'array_length(%s, 1)' % lhs, params
  
 
</s> remove     def as_sql(self, compiler, connection):
        lhs, lhs_params = self.process_lhs(compiler, connection)
        rhs, rhs_params = self.process_rhs(compiler, connection)
        params = lhs_params + rhs_params
        return '%s && %s' % (lhs, rhs), params
 </s> add ArrayField.register_lookup(lookups.ContainedBy)
ArrayField.register_lookup(lookups.Overlap) </s> remove 
    def as_sql(self, compiler, connection):
        lhs, params = compiler.compile(self.lhs)
        return 'avals(%s)' % lhs, params
 </s> add  </s> remove class ValuesTransform(Transform):
 </s> add class ValuesTransform(lookups.FunctionTransform): </s> remove     def as_sql(self, compiler, connection):
        lhs, params = compiler.compile(self.lhs)
        return 'akeys(%s)' % lhs, params

 </s> add  </s> remove 
    def as_postgresql(self, compiler, connection):
        lhs, params = compiler.compile(self.lhs)
        return "UNACCENT(%s)" % lhs, params
 </s> add     function = 'UNACCENT'
    output_field = IntegerField()
  
  @ArrayField.register_lookup
  class ArrayLenTransform(Transform):
      lookup_name = 'len'
    output_field = IntegerField()
    output_field = IntegerField()
    output_field = IntegerField()
    output_field = IntegerField()
  
      def as_sql(self, compiler, connection):
          lhs, params = compiler.compile(self.lhs)
          return 'array_length(%s, 1)' % lhs, params
  
keep keep keep keep replace replace replace replace keep keep keep keep keep
 Move % addition to lookups, refactor postgres lookups.

These refactorings making overriding some text based lookup names on
other fields (specifically `contains`) much cleaner. It also removes a
bunch of duplication in the contrib.postgres lookups. 
django/contrib/postgres/fields/array.py