Google App Engine

The QueryOptions Class

Class QueryOptions provides options for post-processing query results based on the needs of your application. You construct the class as the options in the Query.options argument.

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

  1. Introduction
  2. Constructor
  3. Properties:

Introduction

Class QueryOptions provides options for post-processing the results for a specific query. Options include the ability to sort results, control which document fields to return, produce snippets of fields and compute and sort by complex scoring expressions.

If you wish to randomly access pages of search results, you can use an offset:

from google.appengine.api import search
...
# get the first set of results
page_size = 10
results = index.search(search.Query(query_string='some stuff',
    search.QueryOptions(limit=page_size))

# calculate pages
pages = results.found_count / page_size

# user chooses page and hence an offset into results
next_page = ith * page_size

# get the search results for that page
results = index.search(search.Query(query_string='some stuff',
    search.QueryOptions(limit=page_size, offset=next_page))

For example, the following code fragment requests a search for documents where first occurs in the subject field and good occurs in any field, returning at most 20 documents, requesting the cursor for the next page of results, returning another cursor for the next set of results, sorting by subject in descending order, returning the author, subject, and summary fields as well as a snippeted field content:

...
results = index.search(search.Query(
    query='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'])))

Constructor

The constructor for class QueryOptions is defined as follows:

class QueryOptions(limit=20, number_found_accuracy=None, cursor=None, offset=None, sort_options=None, returned_fields=None, ids_only=False, snippeted_fields=None, returned_expressions=None)

Specify options defining search query results..

Arguments

limit

The limit on number of documents to return in results.

number_found_accuracy

The minimum accuracy requirement for SearchResults.number_found. If set, remains accurate up to at least that number. For example, when set to 100, any SearchResults object with number_found_accuracy <= 100 is accurate.

cursor

A Cursor describing where to get the next set of results, or to provide next cursors in SearchResults.

offset

The offset represents the number of documents to skip in search results. This is an alternative to using a query cursor. It allows random access to the results. Offsets are more expensive (in terms of instance hours) than cursors. You can use either cursor or offset, but not both. Using an offset means that no cursor is returned in ScoredDocument.cursor or ScoredDocument.cursor.

sort_options

A SortOptions object specifying a multi-dimensional sort over search results.

returned_fields

An iterable of names of fields to return in search results.

ids_only

Only return document ids, do not return any fields.

snippeted_fields

An iterable of names of fields to snippet and return in search result expressions.

returned_expressions

An iterable of FieldExpression to evaluate and return in search results.

Result value

A new instance of class QueryOptions.

Exceptions

TypeError

If an unknown iterator_options or sort_options is passed.

ValueError

If ids_only and returned_fields are used together.

Properties

An instance of class Query has the following properties:

limit

Returns a limit on number of documents to return in results.

number_found_accuracy

Returns minimum accuracy requirement for SearchResults.number_found.

cursor

Returns the cursor for the query.

offset

Returns the number of documents in search results to skip.

sort_options

Returns a Returns a SortOptions object.

returned_fields

Returns an iterable of names of fields to return in search results.

ids_only

Returns only in search results.

snippeted_fields

Returns iterable of field names to snippet and return in results.

returned_expressions

Returns iterable of FieldExpression to return in results.

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