elastic.js
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Javascript API for ElasticSearch DSL
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JavaScript
/**
@class
<p>Fuzzy like this query find documents that are “like” provided text by
running it against one or more fields.</p>
<p>Fuzzifies ALL terms provided as strings and then picks the best n
differentiating terms. In effect this mixes the behaviour of FuzzyQuery and
MoreLikeThis but with special consideration of fuzzy scoring factors. This
generally produces good results for queries where users may provide details
in a number of fields and have no knowledge of boolean query syntax and
also want a degree of fuzzy matching and a fast query.</p>
<p>For each source term the fuzzy variants are held in a BooleanQuery with
no coord factor (because we are not looking for matches on multiple variants
in any one doc). Additionally, a specialized TermQuery is used for variants
and does not use that variant term’s IDF because this would favour rarer
terms eg misspellings. Instead, all variants use the same IDF
ranking (the one for the source query term) and this is factored into the
variant’s boost. If the source query term does not exist in the index the
average IDF of the variants is used.</p>
@name ejs.FuzzyLikeThisQuery
@ejs query
@borrows ejs.QueryMixin.boost as boost
@borrows ejs.QueryMixin._type as _type
@borrows ejs.QueryMixin.toJSON as toJSON
@desc
<p>Constructs a query where each documents returned are “like” provided text</p>
@param {String} likeText The text to find documents like it.
*/
ejs.FuzzyLikeThisQuery = function (likeText) {
var
_common = ejs.QueryMixin('flt'),
query = _common.toJSON();
query.flt.like_text = likeText;
return extend(_common, {
/**
The fields to run the query against. If you call with a single field,
it is added to the existing list of fields. If called with an array
of field names, it replaces any existing values with the new array.
@member ejs.FuzzyLikeThisQuery
@param {(String|String[])} f A single field name or a list of field names.
@returns {Object} returns <code>this</code> so that calls can be chained.
*/
fields: function (f) {
if (query.flt.fields == null) {
query.flt.fields = [];
}
if (f == null) {
return query.flt.fields;
}
if (isString(f)) {
query.flt.fields.push(f);
} else if (isArray(f)) {
query.flt.fields = f;
} else {
throw new TypeError('Argument must be a string or array');
}
return this;
},
/**
The text to find documents like
@member ejs.FuzzyLikeThisQuery
@param {String} s A text string.
@returns {Object} returns <code>this</code> so that calls can be chained.
*/
likeText: function (txt) {
if (txt == null) {
return query.flt.like_text;
}
query.flt.like_text = txt;
return this;
},
/**
Should term frequency be ignored. Defaults to false.
@member ejs.FuzzyLikeThisQuery
@param {Boolean} trueFalse A boolean value
@returns {Object} returns <code>this</code> so that calls can be chained.
*/
ignoreTf: function (trueFalse) {
if (trueFalse == null) {
return query.flt.ignore_tf;
}
query.flt.ignore_tf = trueFalse;
return this;
},
/**
The maximum number of query terms that will be included in any
generated query. Defaults to 25.
@member ejs.FuzzyLikeThisQuery
@param {Integer} max A positive integer value.
@returns {Object} returns <code>this</code> so that calls can be chained.
*/
maxQueryTerms: function (max) {
if (max == null) {
return query.flt.max_query_terms;
}
query.flt.max_query_terms = max;
return this;
},
/**
The minimum similarity of the term variants. Defaults to 0.5.
@member ejs.FuzzyLikeThisQuery
@param {Double} min A positive double value.
@returns {Object} returns <code>this</code> so that calls can be chained.
*/
minSimilarity: function (min) {
if (min == null) {
return query.flt.min_similarity;
}
query.flt.min_similarity = min;
return this;
},
/**
Length of required common prefix on variant terms. Defaults to 0..
@member ejs.FuzzyLikeThisQuery
@param {Integer} len A positive integer value.
@returns {Object} returns <code>this</code> so that calls can be chained.
*/
prefixLength: function (len) {
if (len == null) {
return query.flt.prefix_length;
}
query.flt.prefix_length = len;
return this;
},
/**
The analyzer that will be used to analyze the text. Defaults to the
analyzer associated with the field.
@member ejs.FuzzyLikeThisQuery
@param {String} analyzerName The name of the analyzer.
@returns {Object} returns <code>this</code> so that calls can be chained.
*/
analyzer: function (analyzerName) {
if (analyzerName == null) {
return query.flt.analyzer;
}
query.flt.analyzer = analyzerName;
return this;
},
/**
Should the <code>Query</code> fail when an unsupported field
is specified. Defaults to true.
@member ejs.FuzzyLikeThisQuery
@param {Boolean} trueFalse A boolean value
@returns {Object} returns <code>this</code> so that calls can be chained.
*/
failOnUnsupportedField: function (trueFalse) {
if (trueFalse == null) {
return query.flt.fail_on_unsupported_field;
}
query.flt.fail_on_unsupported_field = trueFalse;
return this;
}
});
};