MongoDB- Find a document with an array containing a specific value
Today in this article, we will see how to query MongoDB- Find document with array contains a specific value.
Updated October 2026: a section on $in vs $all vs $elemMatch, a range and aggregation section with index notes, and an FAQ.
We will cover below a few specific scenarios like dealing with [] array type elements,
- Get documents based on matching array size i.e where array size is greater or less than of given specified size.
- Find the array that contains specific values only.
- Specify conditions for array elements.
Today in this article, we will cover below aspects,
MongoDB – Find document by specified array value
Command
{ <field>: {<value> }
The below example shows an array filter where we get the list of documents where the value of an array element i.e books[] is equal to the value specified.
Example
{ books: "white"}
MongoDB – Find documents by an array length
Command
{ <array-field>: {$size :<size-specified> }
The below example shows an array filter where we get the list of documents based on array size i.e domain [] size is equal to the size specified.
Example
{ domain: { $size: 1} }
MongoDB – Find a document with an array by specifying multiple conditions
Command
{ <field>: {$gt :<size-specified> }
The below example shows an array filter where we get the list of documents where the value of any array element i.e domain [] is greater than 14.
{ domain: { $gt: 14 } }
The above query returns all the documents where an array field “domain” contains value 14.
References: MongoDB Naming Standards and Guidelines
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Frequently asked questions
How do I find documents where an array contains a specific value in MongoDB?
Use plain equality on the array field, for example find({ tags: "red" }). It matches any document where at least one element equals the value. The same filter shape works in mongosh and in drivers such as Node.js, where you’d write db.collection('inventory').find({ tags: 'red' }).
Don’t pass a whole array like { tags: ["red", "blank"] } unless you want an exact match. That form requires the same elements in the same order as the stored array.
What is the difference between $in and $all in MongoDB?
$in matches if the array has at least one of the listed values. $all matches only if the array contains every listed value, in any order, and extra elements are allowed. $all with an empty array matches nothing, which surprises many people.
As a rule of thumb, { tags: { $all: ["a", "b"] } } behaves like an $and of two plain equality conditions, one for each value.
When do I need $elemMatch instead of plain equality or dot notation?
Use $elemMatch when several conditions must hold on the same array element, such as a range on a scalar array or two fields of an embedded document. Without it, different elements can satisfy different conditions.
For example, { dim_cm: { $gt: 15, $lt: 20 } } can match when one element is above 15 and another is below 20. Wrapping the same conditions in $elemMatch forces one element to meet both. The same applies to 'lineItems.productId' and 'lineItems.qty' written as separate dot-notation conditions.
Does MongoDB use an index when querying an array field?
Yes. A multikey index like createIndex({ tags: 1 }) supports equality and $in queries on the array. Confirm it with explain() and check that the winning plan uses an index scan rather than a collection scan.
The aggregation form { $match: { $expr: { $in: ["mongodb", "$tags"] } } } doesn’t use the index the way the query operator does. Prefer the plain query filter in $match, and keep that stage early in the pipeline.