Source code for linode_api4.objects.filtering

"""
.. module:: linode

Collections returned by the :any:`LinodeClient` can be filtered using a
SQLAlchemy-like syntax.  When calling any "get" method of the :any:`LinodeClient`
class of one of its groups, any number of filters may be passed in as boolean
comparisons between attributes of the model returned by the collection.

For example, calling :any:`instances` returns a list of :any:`Instance`
objects, so we can use properties of :any:`Instance` to filter the results::

   # returns all Instances in the "prod" group
   client.linode.instances(Instance.group == "prod")

You can use any boolean comparisons when filtering collections::

   # returns all Instances _not_ in us-east-1a
   client.linode.instances(Instance.region != "us-east-1a")

You can combine filters to be even more specific - by default all filters are
considered::

   # returns all Instances in the "prod" group that are in us-east-1a
   client.linode.instances(Instance.group == "prod",
                               Instance.region == "us-east-1a")

If you need to combine the results of two filters, you can use :any:`or_` to define
this relationship::

   # returns all Instance in either the "prod" or "staging" groups
   client.linode.instances(or_(Instance.group == "prod",
                                   Instance.group == "staging"))

:any:`and_` is also available in case you need to do deeply-nested comparisons::

   # returns all Instances in the group "staging" and any Instances in the "prod"
   # group that are located in "us-east-1a"
   client.linode.instances(or_(Instance.group == "staging",
                                   and_(Instance.group == "prod",
                                        Instance.region == "us-east-1a"))

"""


[docs]def or_(a, b): """ Combines two :any:`Filters<Filter>` with an "or" operation, matching any results that match any of the given filters. :param a: The first filter to consider. :type a: Filter :param b: The second filter to consider. :type b: Filter :returns: A filter that matches either a or b :rtype: Filter """ if not isinstance(a, Filter) or not isinstance(b, Filter): raise TypeError return a.__or__(b)
[docs]def and_(a, b): """ Combines two :any:`Filters<Filter>` with an "and" operation, matching any results that match both of the given filters. :param a: The first filter to consider. :type a: Filter :param b: The second filter to consider. :type b: Filter :returns: A filter that matches both a and b :rtype: Filter """ return a.__and__(b)
[docs]def order_by(field, desc=False): """ Allows ordering of results. You may only ever order a collection's results once in a given request. For example:: # sort results by Instances group client.linode.instances(order_by(Instance.group)) :param field: The field to order results by. Must be a filterable attribute of the model. :type field: FilterableAttribute :param desc: If True, return results in descending order. Defaults to False :type desc: bool :returns: A filter that will order results as requested. :rtype: Filter """ return Filter({}).order_by(field, desc)
[docs]def limit(amount): """ Allows limiting of results in a collection. You may only ever apply a limit once per request. For example:: # returns my first 5 Instances client.linode.instances(limit(5)) :param amount: The number of results to return. :type amount: int :returns: A filter that will limit the number of results returned. :rtype: Filter """ return Filter({}).limit(amount)
[docs]class Filter: """ A Filter represents a comparison to send to the API. These should not be constructed normally, but instead should be returned from comparisons between class attributes of filterable classes (see above). Filters can be combined with :any:`and_` and :any:`or_`. """ def __init__(self, dct): self.dct = dct def __or__(self, other): if not isinstance(other, Filter): raise TypeError("You can only or Filter types!") if '+or' in self.dct: return Filter({ '+or': self.dct['+or'] + [ other.dct ] }) else: return Filter({ '+or': [self.dct, other.dct] }) def __and__(self, other): if not isinstance(other, Filter): raise TypeError("You can only and Filter types!") if '+and' in self.dct: return Filter({ '+and': self.dct['+and'] + [ other.dct ] }) else: return Filter({ '+and': [self.dct, other.dct] }) def order_by(self, field, desc=False): # we can't include two order_bys if '+order_by' in self.dct: raise AssertionError("You may only order by once!") if not isinstance(field, FilterableAttribute): raise TypeError("Can only order by filterable attributes!") self.dct['+order_by'] = field.name if desc: self.dct['+order'] = 'desc' return self def limit(self, limit): # we can't limit twice if '+limit' in self.dct: raise AssertionError("You may only limit once!") if not type(limit) == int: raise TypeError("Limit must be an int!") self.dct['+limit'] = limit return self
class FilterableAttribute: def __init__(self, name): self.name = name def __eq__(self, other): return Filter({ self.name: other }) def __ne__(self, other): return Filter({ self.name: { "+neq": other } }) # "in" evaluates the return value - have to use # type.contains instead def contains(self, other): return Filter({ self.name: { "+contains": other } }) def __gt__(self, other): return Filter({ self.name: { "+gt": other } }) def __lt__(self, other): return Filter({ self.name: { "+lt": other } }) def __ge__(self, other): return Filter({ self.name: { "+gte": other } }) def __le__(self, other): return Filter({ self.name: { "+lte": other } }) class NonFilterableAttribute: def __init__(self, clsname, atrname): self.clsname = clsname self.atrname = atrname def __eq__(self, other): raise AttributeError("{} cannot be filtered by {}".format(self.clsname, self.atrname)) def __ne__(self, other): raise AttributeError("{} cannot be filtered by {}".format(self.clsname, self.atrname)) def contains(self, other): raise AttributeError("{} cannot be filtered by {}".format(self.clsname, self.atrname)) def __gt__(self, other): raise AttributeError("{} cannot be filtered by {}".format(self.clsname, self.atrname)) def __lt__(self, other): raise AttributeError("{} cannot be filtered by {}".format(self.clsname, self.atrname)) def __ge__(self, other): raise AttributeError("{} cannot be filtered by {}".format(self.clsname, self.atrname)) def __le__(self, other): raise AttributeError("{} cannot be filtered by {}".format(self.clsname, self.atrname)) class FilterableMetaclass(type): def __init__(cls, name, bases, dct): if hasattr(cls, 'properties'): for key in cls.properties.keys(): setattr(cls, key, FilterableAttribute(key)) super().__init__(name, bases, dct)