wildcard¶
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Definition¶
wildcard
¶The
wildcard
operator enables queries which use special characters in the search string that can match any character.CharacterDescription?
Matches any single character.*
Matches 0 or more characters.\
Escape character.wildcard
is a term-level operator, meaning that thequery
field is not analyzed. Term-level operators work well with the Keyword Analyzer, because thequery
field is treated as a single term, with special characters included. For an example of querying against an analyzedquery
field vs. a non-analyzedquery
field, see the analyzed field example.
Syntax¶
wildcard
has the following syntax:
{ $search: { "index": <index name>, // optional, defaults to "default" "wildcard": { "query": "<search-string>", "path": "<field-to-search>", "allowAnalyzedField": <boolean>, "score": <options> } } }
Options¶
wildcard
uses the following terms to construct a query:
Field | Type | Description | Necessity | Default |
---|---|---|---|---|
query | string or array of strings | String or strings to search for. | yes | |
path | string or array of strings | Indexed field or fields to search. You can also specify a
wildcard path to search. See path
construction for more information. | yes | |
allowAnalyzedField | boolean | Must be set to true if the query is run against an
analyzed field. | no | false |
score | object | Modify the score assigned to matching search term results. Options are:
| no |
Behavior¶
wildcard
is a term-level operator, meaning that the query
field
is not analyzed. It is possible to use the wildcard
operator to
perform searches on an analyzed field by setting the
allowAnalyzedField
option to true
, but you may get unexpected
results.
Searching for *Star Trek*
on a field indexed with the
keyword
analyzer finds all documents in which the field contains
the string Star Trek
in any context. Searching for *Star
Trek*
on a field indexed with the standard analyzer finds nothing, because there is a space
between Star
and Trek
, and the index contains no spaces.
Escape Character Behavior¶
When using the escape character in mongosh
or with a driver, you must use a double backslash before the character to be escaped.
To create a wildcard expression which searches for any string containing a literal asterisk in an aggregation pipeline, use the following expression:
"*\\**"
The first and last asterisks act as wildcards which match any
characters, and the \\*
matches a literal asterisk.
Use the following expression to escape a literal backslash:
"*\\\*"
➤ Use the Select your language drop-down menu to set the language of the examples on this page.
Examples¶
The following examples use the movies
collection in the
sample_mflix
database with a custom index definition that uses the
keyword analyzer. If you have the
sample dataset on your cluster, you
can create an Atlas Search index on the movies
collection and run the
example queries on your cluster.
If you've already loaded the sample dataset, follow the Get Started with Atlas Search tutorial to create an index definition and run Atlas Search queries.
Index Definition¶
The following index definition indexes the title
field in the
movies
collection with the keyword analyzer:
1 { 2 "mappings": { 3 "fields": { 4 "title": { 5 "analyzer": "lucene.keyword", 6 "type": "string" 7 } 8 } 9 } 10 }
The following example searches all title
fields for movie titles
that begin with Green D
, followed by any number of other
characters.
The above query returns the following results:
The following example searches all title
fields for movie titles
that begin with the string Wom?n
(where ?
may be any single
character), followed by a space and then any number of additional
characters. The $limit
stage limits the results to 5 documents,
while the $project
stage limits the results to only the title
field.
The above query returns the following results:
Escape Character Example¶
The following example searches for documents in which the title
field ends with a question mark.
The following example is intended to run in mongosh
. For
more information about using the escape characters with a driver,
see Escape Character Behavior.
The *
character in the query
field matches any characters, and
the \\?
string matches a literal question mark. The $limit
stage
limits the results to 5 documents, while the $project
stage limits
the results to only the title
field.
The above query returns the following results: