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App Engine Python SDK
v1.6.9 rev.445
The Python runtime is available as an experimental Preview feature.
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Public Member Functions | |
def | __init__ |
def | Order |
def | Hint |
def | Ancestor |
def | IsKeysOnly |
def | GetQueryOptions |
def | GetQuery |
def | GetOrder |
def | GetFilterPredicate |
def | GetDistinct |
def | GetIndexList |
def | GetCursor |
def | GetBatcher |
def | Run |
def | Get |
def | Count |
def | __iter__ |
def | __getstate__ |
def | __setstate__ |
def | __setitem__ |
def | setdefault |
def | __delitem__ |
def | update |
def | copy |
Static Public Attributes | |
ASCENDING = datastore_query.PropertyOrder.ASCENDING | |
DESCENDING = datastore_query.PropertyOrder.DESCENDING | |
ORDER_FIRST = datastore_query.QueryOptions.ORDER_FIRST | |
ANCESTOR_FIRST = datastore_query.QueryOptions.ANCESTOR_FIRST | |
FILTER_FIRST = datastore_query.QueryOptions.FILTER_FIRST | |
dictionary | OPERATORS = {'==': datastore_query.PropertyFilter._OPERATORS['=']} |
INEQUALITY_OPERATORS = datastore_query.PropertyFilter._INEQUALITY_OPERATORS | |
tuple | UPPERBOUND_INEQUALITY_OPERATORS = frozenset(['<', '<=']) |
tuple | FILTER_REGEX |
GetCompiledQuery = _GetCompiledQuery | |
GetCompiledCursor = GetCursor | |
A datastore query. (Instead of this, consider using appengine.ext.gql.Query! It provides a query language interface on top of the same functionality.) Queries are used to retrieve entities that match certain criteria, including app id, kind, and property filters. Results may also be sorted by properties. App id and kind are required. Only entities from the given app, of the given type, are returned. If an ancestor is set, with Ancestor(), only entities with that ancestor are returned. Property filters are used to provide criteria based on individual property values. A filter compares a specific property in each entity to a given value or list of possible values. An entity is returned if its property values match *all* of the query's filters. In other words, filters are combined with AND, not OR. If an entity does not have a value for a property used in a filter, it is not returned. Property filters map filter strings of the form '<property name> <operator>' to filter values. Use dictionary accessors to set property filters, like so: > query = Query('Person') > query['name ='] = 'Ryan' > query['age >='] = 21 This query returns all Person entities where the name property is 'Ryan', 'Ken', or 'Bret', and the age property is at least 21. Another way to build this query is: > query = Query('Person') > query.update({'name =': 'Ryan', 'age >=': 21}) The supported operators are =, >, <, >=, and <=. Only one inequality filter may be used per query. Any number of equals filters may be used in a single Query. A filter value may be a list or tuple of values. This is interpreted as multiple filters with the same filter string and different values, all ANDed together. For example, this query returns everyone with the tags "google" and "app engine": > Query('Person', {'tag =': ('google', 'app engine')}) Result entities can be returned in different orders. Use the Order() method to specify properties that results will be sorted by, and in which direction. Note that filters and orderings may be provided at any time before the query is run. When the query is fully specified, Run() runs the query and returns an iterator. The query results can be accessed through the iterator. A query object may be reused after it's been run. Its filters and orderings can be changed to create a modified query. If you know how many result entities you need, use Get() to fetch them: > query = Query('Person', {'age >': 21}) > for person in query.Get(4): > print 'I have four pints left. Have one on me, %s!' % person['name'] If you don't know how many results you need, or if you need them all, you can get an iterator over the results by calling Run(): > for person in Query('Person', {'age >': 21}).Run(): > print 'Have a pint on me, %s!' % person['name'] Get() is more efficient than Run(), so use Get() whenever possible. Finally, the Count() method returns the number of result entities matched by the query. The returned count is cached; successive Count() calls will not re-scan the datastore unless the query is changed.
def google.appengine.api.datastore.Query.__init__ | ( | self, | |
kind = None , |
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filters = {} , |
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_app = None , |
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keys_only = False , |
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compile = True , |
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cursor = None , |
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namespace = None , |
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end_cursor = None , |
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projection = None , |
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distinct = None , |
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_namespace = None |
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Constructor. Raises BadArgumentError if kind is not a string. Raises BadValueError or BadFilterError if filters is not a dictionary of valid filters. Args: namespace: string, the namespace to query. kind: string, the kind of entities to query, or None. filters: dict, initial set of filters. keys_only: boolean, if keys should be returned instead of entities. projection: iterable of property names to project. distinct: boolean, if projection should be distinct. compile: boolean, if the query should generate cursors. cursor: datastore_query.Cursor, the start cursor to use. end_cursor: datastore_query.Cursor, the end cursor to use. _namespace: deprecated, use namespace instead.
def google.appengine.api.datastore.Query.__delitem__ | ( | self, | |
filter | |||
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Implements the del [] operator. Used to remove filters.
def google.appengine.api.datastore.Query.__setitem__ | ( | self, | |
filter, | |||
value | |||
) |
Implements the [] operator. Used to set filters. If the filter string is empty or not a string, raises BadFilterError. If the value is not a supported type, raises BadValueError.
def google.appengine.api.datastore.Query.Ancestor | ( | self, | |
ancestor | |||
) |
Sets an ancestor for this query. This restricts the query to only return result entities that are descended from a given entity. In other words, all of the results will have the ancestor as their parent, or parent's parent, or etc. Raises BadArgumentError or BadKeyError if parent is not an existing Entity or Key in the datastore. Args: # the key must be complete ancestor: Entity or Key Returns: # this query Query
def google.appengine.api.datastore.Query.copy | ( | self | ) |
The copy method is not supported.
def google.appengine.api.datastore.Query.Count | ( | self, | |
limit = 1000 , |
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kwargs | |||
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Returns the number of entities that this query matches. Args: limit, a number or None. If there are more results than this, stop short and just return this number. Providing this argument makes the count operation more efficient. config: Optional Configuration to use for this request. Returns: The number of results.
def google.appengine.api.datastore.Query.Get | ( | self, | |
limit, | |||
offset = 0 , |
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kwargs | |||
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Deprecated, use list(Run(...)) instead. Args: limit: int or long representing the maximum number of entities to return. offset: int or long representing the number of entities to skip kwargs: Any keyword arguments accepted by datastore_query.QueryOptions(). Returns: # a list of entities [Entity, ...]
def google.appengine.api.datastore.Query.GetBatcher | ( | self, | |
config = None |
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) |
Runs this query and returns a datastore_query.Batcher. This is not intended to be used by application developers. Use Get() instead! Args: config: Optional Configuration to use for this request. Returns: # an iterator that provides access to the query results Iterator
def google.appengine.api.datastore.Query.GetCursor | ( | self | ) |
Get the cursor from the last run of this query. The source of this cursor varies depending on what the last call was: - Run: A cursor that points immediately after the last result pulled off the returned iterator. - Get: A cursor that points immediately after the last result in the returned list. - Count: A cursor that points immediately after the last result counted. Returns: A datastore_query.Cursor object that can be used in subsequent query requests. Raises: AssertionError: The query has not yet been run or cannot be compiled.
def google.appengine.api.datastore.Query.GetDistinct | ( | self | ) |
Returns True if the current instance is distinct. Returns: A boolean indicating if the distinct flag is set.
def google.appengine.api.datastore.Query.GetFilterPredicate | ( | self | ) |
Returns a datastore_query.FilterPredicate for the current instance. Returns: datastore_query.FilterPredicate or None if no filters are set on the current Query.
def google.appengine.api.datastore.Query.GetIndexList | ( | self | ) |
Get the index list from the last run of this query. Returns: A list of indexes used by the last run of this query. Raises: AssertionError: The query has not yet been run.
def google.appengine.api.datastore.Query.GetOrder | ( | self | ) |
Gets a datastore_query.Order for the current instance. Returns: datastore_query.Order or None if there are no sort orders set on the current Query.
def google.appengine.api.datastore.Query.GetQuery | ( | self | ) |
Returns a datastore_query.Query for the current instance.
def google.appengine.api.datastore.Query.GetQueryOptions | ( | self | ) |
Returns a datastore_query.QueryOptions for the current instance.
def google.appengine.api.datastore.Query.Hint | ( | self, | |
hint | |||
) |
Sets a hint for how this query should run. The query hint gives us information about how best to execute your query. Currently, we can only do one index scan, so the query hint should be used to indicates which index we should scan against. Use FILTER_FIRST if your first filter will only match a few results. In this case, it will be most efficient to scan against the index for this property, load the results into memory, and apply the remaining filters and sort orders there. Similarly, use ANCESTOR_FIRST if the query's ancestor only has a few descendants. In this case, it will be most efficient to scan all entities below the ancestor and load them into memory first. Use ORDER_FIRST if the query has a sort order and the result set is large or you only plan to fetch the first few results. In that case, we shouldn't try to load all of the results into memory; instead, we should scan the index for this property, which is in sorted order. Note that hints are currently ignored in the v3 datastore! Arg: one of datastore.Query.[ORDER_FIRST, ANCESTOR_FIRST, FILTER_FIRST] Returns: # this query Query
def google.appengine.api.datastore.Query.IsKeysOnly | ( | self | ) |
Returns True if this query is keys only, false otherwise.
def google.appengine.api.datastore.Query.Order | ( | self, | |
orderings | |||
) |
Specify how the query results should be sorted. Result entities will be sorted by the first property argument, then by the second, and so on. For example, this: > query = Query('Person') > query.Order('bday', ('age', Query.DESCENDING)) sorts everyone in order of their birthday, starting with January 1. People with the same birthday are sorted by age, oldest to youngest. The direction for each sort property may be provided; if omitted, it defaults to ascending. Order() may be called multiple times. Each call resets the sort order from scratch. If an inequality filter exists in this Query it must be the first property passed to Order. Any number of sort orders may be used after the inequality filter property. Without inequality filters, any number of filters with different orders may be specified. Entities with multiple values for an order property are sorted by their lowest value. Note that a sort order implies an existence filter! In other words, Entities without the sort order property are filtered out, and *not* included in the query results. If the sort order property has different types in different entities - ie, if bob['id'] is an int and fred['id'] is a string - the entities will be grouped first by the property type, then sorted within type. No attempt is made to compare property values across types. Raises BadArgumentError if any argument is of the wrong format. Args: # the properties to sort by, in sort order. each argument may be either a # string or (string, direction) 2-tuple. Returns: # this query Query
def google.appengine.api.datastore.Query.Run | ( | self, | |
kwargs | |||
) |
Runs this query. If a filter string is invalid, raises BadFilterError. If a filter value is invalid, raises BadValueError. If an IN filter is provided, and a sort order on another property is provided, raises BadQueryError. If you know in advance how many results you want, use limit=#. It's more efficient. Args: kwargs: Any keyword arguments accepted by datastore_query.QueryOptions(). Returns: # an iterator that provides access to the query results Iterator
def google.appengine.api.datastore.Query.setdefault | ( | self, | |
filter, | |||
value | |||
) |
If the filter exists, returns its value. Otherwise sets it to value. If the property name is the empty string or not a string, raises BadPropertyError. If the value is not a supported type, raises BadValueError.
def google.appengine.api.datastore.Query.update | ( | self, | |
other | |||
) |
Updates this query's filters from the ones in other. If any filter string is invalid, raises BadFilterError. If any value is not a supported type, raises BadValueError.
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