104 lines
3.0 KiB
Markdown
104 lines
3.0 KiB
Markdown
django-mysqlfulltextsearch
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==============================
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django-mysqlfulltextsearch is a simple plug-in for Django that
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provides access to MySQL's FULLTEXT INDEX feature available in MySQL
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5.0 and up.
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Although Django supports the "search" lookup in QuerySet filters
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[http://docs.djangoproject.com/en/dev/ref/models/querysets/#search],
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the docs specify that you must create the fulltext index yourself.
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This variant, inspired by code from a blog entry by Andrew Durdin
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[http://www.mercurytide.co.uk/news/article/django-full-text-search/],
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includes a return value "relevance," which is the score MySQL awards
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to each row returned. This is a win for small sites that do not need
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a heavyweight search solution such as Lucene or Xapian. ("relevance"
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is supposed to be a configurable dynamic field name, but I haven't
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provided a reliable path to change it yet.)
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Along with the updated API, this code provides for index discovery.
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If a table has exactly one fulltext index, you can create a
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SearchManager without declaring any fields at all, and it will
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auto-discover the index on its own. If you specify a tuple of search
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fields for which no corresponding index exists, the returned exception
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will include a list of valid indices.
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Standard Usage:
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---------------
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Create the index. For the model "book" in the app "Books":
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./manage dbshell
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> CREATE FULLTEXT INDEX book_title on books_book (title, summary)
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Or via South:
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def forwards(self, orm):
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db.execute('CREATE FULLTEXT INDEX book_text_index ON books_book (title, summary)')
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Using the index:
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from mysqlfulltextsearch import SearchManager
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class Books:
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...
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objects = SearchManager()
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books = Book.objects.search('The Metamorphosis', ('title', 'summary')).order_by('-relevance')
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> books[0].title
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"The Metamorphosis"
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> books[0].author
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"Franz Kafka"
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> books[0].relevance
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9.4
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If there is only one index for the table, the fields do not need to be
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specified, the SearchQuerySet object can find it automatically:
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from mysqlfulltextsearch import SearchManager
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class Books:
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...
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objects = SearchManager()
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books = Book.objects.search('The Metamorphosis').order_by('-relevance')
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Tips:
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-----
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Generating the index is a relatively heavyweight process. When you
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have a few thousand documents, it might be best to load them first,
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then generate the index afterward.
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To Do:
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-----
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-- Easy
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Make the "relevance" dynamic field name configurable.
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-- Moderate
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Provide means for matching against BOOLEAN, NATURAL LANGUAGE, and
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QUERY EXPANSION modes. (Preliminary experiments with this revealed
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some... interesting... problems with parameter quotation.)
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-- Difficult
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Provide means for using a SearchManager to access indices on joined
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tables, for example:
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Author.objects.search("The Metamorphosis", ("book__title",))
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-- Insane
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Provide for a way to have FULLTEXT search indices specified in a
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model's Meta class, and have syncdb or south pick up that information
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and do the right thing with it.
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