new Builder()
lunr.Builder performs indexing on a set of documents and returns instances of lunr.Index ready for querying.
All configuration of the index is done via the builder, the fields to index, the document reference, the text processing pipeline and document scoring parameters are all set on the builder before indexing.
Properties:
| Name | Type | Description |
|---|---|---|
_ref |
string | Internal reference to the document reference field. |
_fields |
Array.<string> | Internal reference to the document fields to index. |
invertedIndex |
object | The inverted index maps terms to document fields. |
documentTermFrequencies |
object | Keeps track of document term frequencies. |
documentLengths |
object | Keeps track of the length of documents added to the index. |
tokenizer |
lunr.tokenizer | Function for splitting strings into tokens for indexing. |
pipeline |
lunr.Pipeline | The pipeline performs text processing on tokens before indexing. |
searchPipeline |
lunr.Pipeline | A pipeline for processing search terms before querying the index. |
documentCount |
number | Keeps track of the total number of documents indexed. |
_b |
number | A parameter to control field length normalization, setting this to 0 disabled normalization, 1 fully normalizes field lengths, the default value is 0.75. |
_k1 |
number | A parameter to control how quickly an increase in term frequency results in term frequency saturation, the default value is 1.2. |
termIndex |
number | A counter incremented for each unique term, used to identify a terms position in the vector space. |
metadataWhitelist |
array | A list of metadata keys that have been whitelisted for entry in the index. |
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Methods
add(doc, attributes)
Adds a document to the index.
Before adding fields to the index the index should have been fully setup, with the document ref and all fields to index already having been specified.
The document must have a field name as specified by the ref (by default this is 'id') and it should have all fields defined for indexing, though null or undefined values will not cause errors.
Entire documents can be boosted at build time. Applying a boost to a document indicates that this document should rank higher in search results than other documents.
Parameters:
| Name | Type | Description | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
doc |
object | The document to add to the index. |
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attributes |
object | Optional attributes associated with this document. Properties
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b(number)
A parameter to tune the amount of field length normalisation that is applied when calculating relevance scores. A value of 0 will completely disable any normalisation and a value of 1 will fully normalise field lengths. The default is 0.75. Values of b will be clamped to the range 0 - 1.
Parameters:
| Name | Type | Description |
|---|---|---|
number |
number | The value to set for this tuning parameter. |
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build() → {lunr.Index}
Builds the index, creating an instance of lunr.Index.
This completes the indexing process and should only be called once all documents have been added to the index.
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Returns:
- Type
- lunr.Index
field(fieldName, attributes)
Adds a field to the list of document fields that will be indexed. Every document being indexed should have this field. Null values for this field in indexed documents will not cause errors but will limit the chance of that document being retrieved by searches.
All fields should be added before adding documents to the index. Adding fields after a document has been indexed will have no effect on already indexed documents.
Fields can be boosted at build time. This allows terms within that field to have more importance when ranking search results. Use a field boost to specify that matches within one field are more important than other fields.
Parameters:
| Name | Type | Description | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
fieldName |
string | The name of a field to index in all documents. |
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attributes |
object | Optional attributes associated with this field. Properties
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Throws:
-
fieldName cannot contain unsupported characters '/'
- Type
- RangeError
k1(number)
A parameter that controls the speed at which a rise in term frequency results in term frequency saturation. The default value is 1.2. Setting this to a higher value will give slower saturation levels, a lower value will result in quicker saturation.
Parameters:
| Name | Type | Description |
|---|---|---|
number |
number | The value to set for this tuning parameter. |
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ref(ref)
Sets the document field used as the document reference. Every document must have this field. The type of this field in the document should be a string, if it is not a string it will be coerced into a string by calling toString.
The default ref is 'id'.
The ref should not be changed during indexing, it should be set before any documents are added to the index. Changing it during indexing can lead to inconsistent results.
Parameters:
| Name | Type | Description |
|---|---|---|
ref |
string | The name of the reference field in the document. |
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use(plugin)
Applies a plugin to the index builder.
A plugin is a function that is called with the index builder as its context. Plugins can be used to customise or extend the behaviour of the index in some way. A plugin is just a function, that encapsulated the custom behaviour that should be applied when building the index.
The plugin function will be called with the index builder as its argument, additional arguments can also be passed when calling use. The function will be called with the index builder as its context.
Parameters:
| Name | Type | Description |
|---|---|---|
plugin |
function | The plugin to apply. |
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