Google App Engine

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.

  1. Introduction
  2. Constructor
  3. Properties:

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.

from google.appengine.api import 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=queryString, options=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 < 2011-02-28 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.

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_strong 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.

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