$regex
The $regex operator is used to perform pattern matching with regular expressions.
This operator is useful for querying string fields for matches that fit specific patterns. Common use cases include searching for documents where a field contains a substring, starts with a certain prefix, or matches a complex pattern.
Syntax
{
"field": {
$regex: /pattern/,
$options: '<options>'
}
}
Parameters
| Description | |
|---|---|
field |
Required. The field in the document you want to query. |
/pattern/ |
Required. The regular expression pattern you want to match. |
options |
Optional. Flags to modify the behavior of the regex. Common options include, but are not limited to i for case-insensitive matching, m for multiline matching, etc. |
Examples
Consider this sample set of documents within the stores collection for these examples.
[
{
"_id": "aaaaaaaa-0000-1111-2222-bbbbbbbbbbbb",
"name": "Proseware, Inc. | Home Entertainment Hub - East Linwoodbury"
},
{
"_id": "bbbbbbbb-1111-2222-3333-cccccccccccc",
"name": "Fabrikam, Inc. | Home Accessory Outlet - West Adele"
},
{
"_id": "cccccccc-2222-3333-4444-dddddddddddd",
"name": "Wide World Importers | Fitness Equipment Outlet - Reillyborough"
}
]
Find documents with a specific substring
Use the regex operator to find all documents that match a specific pattern. In this example, the operator filters to documents that contain the exact phrase Home in its name.
db.stores.find({ "name": { "$regex": /Home/ }})
[
{
"_id": "aaaaaaaa-0000-1111-2222-bbbbbbbbbbbb",
"name": "Proseware, Inc. | Home Entertainment Hub - East Linwoodbury"
},
{
"_id": "bbbbbbbb-1111-2222-3333-cccccccccccc",
"name": "Fabrikam, Inc. | Home Accessory Outlet - West Adele"
}
]
Find documents using a case-insensitive match
The $regex operator includes options like case-insensitive search. In this example, the operator filters to documents that contain the case-insensitive phrase outlet in its name.
db.stores.find({ "name": { $regex: /outlet/, $options: "i" }})
[
{
"_id": "bbbbbbbb-1111-2222-3333-cccccccccccc",
"name": "Fabrikam, Inc. | Home Accessory Outlet - West Adele"
},
{
"_id": "cccccccc-2222-3333-4444-dddddddddddd",
"name": "Wide World Importers | Fitness Equipment Outlet - Reillyborough"
}
]