Filter expression reference

The filter search parameter expects a filter expression. Filter expressions are made of attributes, values, and several operators.

filter expects a filter expression containing one or more conditions. A filter expression can be written as a string, array, or mix of both.

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Data types

Filters accept numeric and string values. Empty fields or fields containing an empty array will be ignored.

Filters do not work with NaN and infinite values such as inf and -inf as they are not supported by JSON. It is possible to filter infinite and NaN values if you parse them as strings, except when handling _geo fields.

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Conditions

Conditions are a filter’s basic building blocks. They are written in the attribute OPERATOR value format, where:

• attribute is the attribute of the field you want to filter on
• OPERATOR can be =, !=, >, >=, <, <=, TO, EXISTS, IN, NOT, AND, or OR
• value is the value the OPERATOR should look for in the attribute

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Examples

A basic condition requesting movies whose genres attribute is equal to horror:

genres = horror

String values containing whitespace must be enclosed in single or double quotes:

director = 'Jordan Peele'
director = "Tim Burton"

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Filter operators

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Equality (=)

The equality operator (=) returns all documents containing a specific value for a given attribute:

genres = action

When operating on strings, = is case-insensitive.

The equality operator does not return any results for null and empty arrays.

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Inequality (!=)

The inequality operator (!=) returns all documents not selected by the equality operator. When operating on strings, != is case-insensitive.

The following expression returns all movies without the action genre:

genres != action

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Comparison (>, <, >=, <=)

The comparison operators (>, <, >=, <=) select documents satisfying a comparison. Comparison operators only apply only to numerical values.

The expression below returns all documents with a user rating above 85:

rating.users > 85

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TO

TO is equivalent to >= AND <=. The following expression returns all documents with a rating of 80 or above but below 90:

rating.users 80 TO 89

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EXISTS

The EXISTS operator checks for the existence of a field. Fields with empty or null values count as existing.

The following expression returns all documents containing the release_date field:

release_date EXISTS

The negated form of the above expression can be written in two equivalent ways:

release_date NOT EXISTS
NOT release_date EXISTS

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IS EMPTY

The IS EMPTY operator selects documents in which the specified attribute exists but contains empty values. The following expression only returns documents with an empty overview field:

overview IS EMPTY

IS EMPTY matches the following JSON values:

• ""
• []
• {}

Meilisearch does not treat null values as empty. To match null fields, use the IS NULL operator.

Use NOT to build the negated form of IS EMPTY:

overview IS NOT EMPTY
NOT overview IS EMPTY

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IS NULL

The IS NULL operator selects documents in which the specified attribute exists but contains a null value. The following expression only returns documents with a null overview field:

overview IS NULL

Use NOT to build the negated form of IS NULL:

overview IS NOT NULL
NOT overview IS NULL

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IN

IN combines equality operators by taking an array of comma-separated values delimited by square brackets. It selects all documents whose chosen field contains at least one of the specified values.

The following expression returns all documents whose genres includes either horror, comedy, or both:

genres IN [horror, comedy]
genres = horror OR genres = comedy

The negated form of the above expression can be written as:

genres NOT IN [horror, comedy]
NOT genres IN [horror, comedy]

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CONTAINS

CONTAINS filters results containing partial matches to the specified string pattern, similar to a SQL LIKE.

The following expression returns all dairy products whose names contain "kef":

dairy_products.name CONTAINS kef

The negated form of the above expression can be written as:

dairy_products.name NOT CONTAINS kef
NOT dairy_product.name CONTAINS kef

curl \
  -X PATCH 'MEILISEARCH_URL/experimental-features/' \
  -H 'Content-Type: application/json' \
  --data-binary '{
    "containsFilter": true
  }'

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STARTS WITH

STARTS WITH filters results whose values start with the specified string pattern.

The following expression returns all dairy products whose name start with "kef":

dairy_products.name STARTS WITH kef

The negated form of the above expression can be written as:

dairy_products.name NOT STARTS WITH kef
NOT dairy_product.name STARTS WITH kef

curl \
  -X PATCH 'MEILISEARCH_URL/experimental-features/' \
  -H 'Content-Type: application/json' \
  --data-binary '{
    "containsFilter": true
  }'

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NOT

The negation operator (NOT) selects all documents that do not satisfy a condition. It has higher precedence than AND and OR.

The following expression will return all documents whose genres does not contain horror and documents with a missing genres field:

NOT genres = horror

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Filter expressions

You can build filter expressions by grouping basic conditions using AND and OR. Filter expressions can be written as strings, arrays, or a mix of both.

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Filter expression grouping operators

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AND

AND connects two conditions and only returns documents that satisfy both of them. AND has higher precedence than OR.

The following expression returns all documents matching both conditions:

genres = horror AND director = 'Jordan Peele'

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OR

OR connects two conditions and returns results that satisfy at least one of them.

The following expression returns documents matching either condition:

genres = horror OR genres = comedy

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Creating filter expressions with string operators and parentheses

Meilisearch reads string expressions from left to right. You can use parentheses to ensure expressions are correctly parsed.

For instance, if you want your results to only include comedy and horror documents released after March 1995, the parentheses in the following query are mandatory:

(genres = horror OR genres = comedy) AND release_date > 795484800

Failing to add these parentheses will cause the same query to be parsed as:

genres = horror OR (genres = comedy AND release_date > 795484800)

Translated into English, the above expression will only return comedies released after March 1995 or horror movies regardless of their release_date.

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Creating filter expressions with arrays

Array expressions establish logical connectives by nesting arrays of strings. Array filters can have a maximum depth of two. Expressions with three or more levels of nesting will throw an error.

Outer array elements are connected by an AND operator. The following expression returns horror movies directed by Jordan Peele:

["genres = horror", "director = 'Jordan Peele'"]

Inner array elements are connected by an OR operator. The following expression returns either horror or comedy films:

[["genres = horror", "genres = comedy"]]

Inner and outer arrays can be freely combined. The following expression returns both horror and comedy movies directed by Jordan Peele:

[["genres = horror", "genres = comedy"], "director = 'Jordan Peele'"]

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Combining arrays and string operators

You can also create filter expressions that use both array and string syntax.

The following filter is written as a string and only returns movies not directed by Jordan Peele that belong to the comedy or horror genres:

"(genres = comedy OR genres = horror) AND director != 'Jordan Peele'"

You can write the same filter mixing arrays and strings:

[["genres = comedy", "genres = horror"], "NOT director = 'Jordan Peele'"]