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Collectors API

Classes and functions for gathering search results. Collectors are used internally by Searcher.search() to collect matching documents and build Results objects. The collectors module is a refactored package exposing the same public API as the former monolithic module.

Overview​

A Collector iterates over matching documents in an index, collects information about them, and produces a Results object. The base Collector class defines the interface; specialized subclasses implement different collection strategies (top-N, unlimited, sorting, filtering, faceting, etc.).

Core Classes​

Collector​

class whoosh.collectors.Collector

Abstract base class for all collectors. Subclasses must implement collect() and results().

Methods:

prepare(top_searcher, q, context)​

Called before a search begins. Sets up self.top_searcher, self.q, self.context, self.starttime, and self.docset.

run()​

Iterates over sub-searchers, calling set_subsearcher() and collect_matches() for each, then calls finish().

set_subsearcher(subsearcher, offset)​

Called when moving to a new sub-searcher. Sets self.subsearcher, self.offset, and self.matcher.

collect(sub_docnum)​

Called for every matched document. Must add the document to results and return a sort key. Subclasses must implement this.

  • sub_docnum: Segment-relative document number. Add self.offset to get the top-level document number.

sort_key(sub_docnum)​

Returns a sort key for the current match without the side effect of adding the document to results. Subclasses must implement this.

collect_matches()​

Calls matches() and then collect() for each matched document.

matches()​

Yields segment-relative document numbers for matches in the current sub-searcher.

count()​

Returns the total number of matching documents.

all_ids()​

Returns a sequence of docnums matched in this collector.

computes_count()​

Returns True if the collector naturally computes the exact count of matching documents.

finish()​

Called after the search completes. Sets self.runtime.

remove(global_docnum)​

Removes a document from the collector using its global docnum.

results()​

Returns a Results object. Subclasses must implement this.

ilen​

whoosh.collectors.ilen(iterator) -> int

Counts the number of items in an iterator without loading it all into memory.

Scored Collectors​

ScoredCollector​

class whoosh.collectors.ScoredCollector(replace=10)

Base class for collectors that sort by document score.

Constructor:

  • replace: Number of matches between attempts to replace the matcher with a more efficient version.

TopCollector​

class whoosh.collectors.TopCollector(
    limit=10,
    usequality=True,
    **kwargs
)

A collector that returns only the top N scored results.

Constructor:

  • limit: Maximum number of results to return.
  • usequality: Whether to use block-quality optimizations for faster search. Can be set to False for debugging.

Notes:

  • When usequality=True, computes_count() returns False and all_ids() requires re-searching.
  • Uses a min-heap to efficiently track the top N documents.

UnlimitedCollector​

class whoosh.collectors.UnlimitedCollector(reverse=False)

A collector that returns all scored results. Sorts by score (descending by default).

Constructor:

  • reverse: If True, sort results in ascending order (lowest scores first).

UnsortedCollector​

class whoosh.collectors.UnsortedCollector

A collector that returns results in document order (no sorting). Used when the search weighting is None.

Wrapping Collectors​

WrappingCollector​

class whoosh.collectors.WrappingCollector(child)

Base class for collectors that wrap other collectors. Delegates most operations to the child collector while adding additional behavior.

Constructor:

  • child: The collector to wrap.

Methods (all delegated to child): top_searcher, context, prepare, set_subsearcher, all_ids, count, collect_matches, sort_key, collect, remove, matches, finish, results()

SortingCollector​

class whoosh.collectors.SortingCollector(
    sortedby,
    limit=10,
    reverse=False
)

A collector that returns results sorted by a FacetType object.

Constructor:

  • sortedby: A FacetType or field name to sort by.
  • limit: Maximum number of results (0 for no limit).
  • reverse: If True, reverse the overall sort order.

FilterCollector​

class whoosh.collectors.FilterCollector(
    child,
    allow=None,
    restrict=None
)

A collector that allows and/or restricts certain document numbers in results.

A document is discarded if:

  • allow is set and the docnum is not in the allowed set, or
  • restrict is set and the docnum is in the restricted set.

Constructor:

  • child: The collector to wrap.
  • allow: A query, Results object, or set-like of allowed docnums. None means everything is allowed.
  • restrict: A query, Results object, or set-like of disallowed docnums. None means nothing is disallowed.

Attributes:

  • filtered_count: Number of documents filtered out.

FacetCollector​

class whoosh.collectors.FacetCollector(child, groupedby, maptype=None)

A collector that creates groups of documents based on facet objects. Used when groupedby is specified in Searcher.search().

Constructor:

  • child: The collector to wrap.
  • groupedby: A field name, FacetType, dict, or Facets object.
  • maptype: Default FacetMap class for facets that don't specify one.

Attributes:

  • facetmaps: Dictionary of facet name to FacetMap objects.

CollapseCollector​

class whoosh.collectors.CollapseCollector(
    child,
    keyfacet,
    limit=1,
    order=None
)

A collector that eliminates all but the top N results sharing the same facet key. Useful for "dedup" or grouped result views.

Constructor:

  • child: The collector to wrap.
  • keyfacet: A FacetType to collapse on. All but the top N documents sharing a key are eliminated.
  • limit: Maximum documents to keep per key (default 1).
  • order: Optional FacetType to determine which documents are "top" within each group. Defaults to the results order (e.g., highest score).

Attributes:

  • collapsed_counts: Dictionary mapping keys to the number of documents eliminated.

TimeLimitCollector​

class whoosh.collectors.TimeLimitCollector(
    child,
    timelimit,
    greedy=False,
    use_alarm=True
)

A collector that raises a TimeLimit exception if the search exceeds a time limit. Partial results are still available via results().

Constructor:

  • child: The collector to wrap.
  • timelimit: Maximum search time in seconds.
  • greedy: If True, finish adding the current hit before raising.
  • use_alarm: If True (default), use signal.SIGALRM on Unix for immediate interruption. On Windows, time is only checked between documents.
from whoosh.searching import TimeLimit

uc = collectors.UnlimitedCollector()
tlc = TimeLimitCollector(uc, timelimit=5.8)
try:
    searcher.search_with_collector(myquery, tlc)
except TimeLimit:
    print("Search timed out!")
# Still get partial results:
print(tlc.results())

TermsCollector​

class whoosh.collectors.TermsCollector(child, settype=set)

A collector that records which terms appeared in which matched documents. Used when terms=True in Searcher.search().

Constructor:

  • child: The collector to wrap.
  • settype: Set type to use for docnum collections (default set).

Attributes:

  • termdocs: Dict mapping (fieldname, text) tuples to arrays of docnums.
  • docterms: Dict mapping docnums to lists of (fieldname, text) tuples.

Exceptions​

TimeLimit​

from whoosh.searching import TimeLimit

Raised by TimeLimitCollector when the search exceeds the time limit. Partial results are still available from the collector.