The Query Class

Class Query represents a request on the search service to query the index.

Query is defined in the google.appengine.api.search module.

Introduction

The Query class allows you to specify a query string and other options, such as sort order, limit, and a cursor, for a search on an index. You set these options by instantiating the QueryOptions class to the Query.options parameter.

For example, the following code fragment requests a search for documents where first occurs in subject and good occurs anywhere, returning at most 20 documents, returning a single document cursor for the results, sorting by subject in descending order, returning the author, subject, and summary fields as well as a snippeted field content.

fromgoogle.appengine.apiimport search
...
results = index.search(search.Query(
 # Specify the query string using the Search API's Query language.
 query_string='subject:first good',
 options=search.QueryOptions(
 limit=20,
 cursor=search.Cursor(),
 sort_options=search.SortOptions(
 expressions=[
 search.SortExpression(expression='subject', default_value='')],
 limit=1000),
 returned_fields=['author', 'subject', 'summary'],
 snippeted_fields=['content'])))
...

You have the option to return a cursor with each set of search results. This cursor allows you to more easily page through search results. To get a Cursor, specify it in QueryOptions.cursor and extract the cursor for the next request from SearchResults.cursor . This allows you to continue your search from the last found document, as shown below:

...
results = index.search(
 search.Query(query_string='subject:first good',
 options=search.QueryOptions(cursor=results.cursor)))

Constructor

The constructor for class Query is defined as follows:

class Query(query_string, options=None, enable_facet_discovery=False, return_facets=None, facet_options=None, facet_refinements=None)

Request the search service to query an index, specifying parameters for that query.

Arguments

query_string

The query to match against documents in the index. A query is a boolean expression containing terms. For example, the query job tag:"very important" sent < 2011年02月28日 finds documents with the term job in any field, and also contain the phrase very important in a tag field, and a sent date prior to February 28, 2011.

options

Instantiation of the QueryOptions class with instructions for post-processing search results.

enable_facet_discovery

Enable the discovery of the most relevant facets used by the documents that satisfy this search query and return them.

return_facets

An iterable of FacetRequest or basestring as facet name to return specific facet with the result.

facet_options

A FacetOption describing processing of facets.

facet_refinements

An iterable of FacetRefinement objects or refinement token strings used to filter out search results based on a facet value. refinements for different facets will be conjunction and refinements for the same facet will be disjunction.

Result value

A new instance of class Query.

Exceptions

TypeError

Raised when query_string is not a string or options is not a QueryOptions object.

ValueError

Raised when the query_string could not be parsed.

Properties

An instance of class Query has the following properties:

query_string

Returns the query string to search in this request.

options

Returns the QueryOptions defining post-processing of the search results.