A DSL to build Lucene text queries in Python.
|synopsis:||A Python DSL for Lucene queries.|
Easily create Lucene query strings without having to learn the language itself. The syntax is simple to use and allows creating larger queries from multiple smaller ones. A basic lesson on proper Lucene queries can be found here.
Supports Python 2.6+.
>>> from lucenequerybuilder import Q
A basic query can be given by passing in a string into Q’s constructor.
>>> q = Q('a')>>> q = Q('The quick brown fox')
The query builder will automatically detect whether a term (no whitespace) or a phrase (multiple terms together seaparated by whitespace) and properly bound them with quotation marks.
All terms and phrases are expected to be unescaped, and will be escaped:
>>> q = Q(r'The *quick* brown (fox)') >>> str(q) '"The \\*quick\\* brown \\(fox\\)"'
Ranges are also easy to put into a query. There are two types of range queries, inclusive range and exclusive range. These are passed into the query builder with keyword arguments.
>>> q = Q(inrange=(1,5))>>> q = Q(exrange=['egg','hgg'])
Ranges will work with any list-like object of length 2.
You can chain queries with & (AND), | (OR), & ~ (AND NOT), + (MUST), and - (MUST NOT). AND, OR, and AND NOT require a query before and after it shows up. MUST and MUST NOT only work on the query directly afterwards. Some examples are below:
>>> q = Q('a') & Q('b') >>> q = Q('a') & ~Q('b') >>> q = +Q('a') -Q('b')
Queries can be nested inside of each other to create new queries. This makes it easy to group queries together. Examples below:
>>> q = Q(Q('a') & Q('b')) & ~Q('c') >>> q = Q(Q(Q('a') | Q(inrange=[1,2])) +Q('c))
Fields can be added to queries by putting in a field as your first argument. Fields cannot have any whitespace and cannot be nested inside each other. The following examples are valid queries:
>>> q = Q('name', 'Edward') >>> q = Q('text', 'Mary had a little lamb') >>> q = Q('age', inrange=[10, 9001])
The following examples are invalid queries which will raise an error:
>>> q = Q('name', Q('lastname', 'Purcell')) >>> q = Q('bad', Q('range', inrange=[10, 9001]))
A fuzzy term query can be accomplished using the fuzzy keyword:
>>> q = Q('name', fuzzy=('edd', .2)) >>> str(q) 'name:(edd~0.200)'
The first element in the fuzzy tuple is the term, and the second is the similarity ratio- a float, str, or decimal between 0 and 1.
If you drop the second element, and just provide a str, the string will signify to use Lucene’s default ratio - 0.5:
>>> q = Q('name', fuzzy='edd') >>> str(q) 'name:(edd~)'
To keep wildcard queries from having ‘?’ and ‘*’ from being escaped, simple include the wildcard flag:
>>> str(Q('c?t', wildcard=True)) 'c?t'
which will match ‘cat’ or ‘cot’.
Boosting & Wildcard Queries
These queries are not yet supported, but will be soon. Feel free to add support yourself and request a pull!
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