Expression language reference

Rule expressions are written using a simple expression language. It provides a rich set of operators and builtin functions, and allows you to create flexible conditions and criteria.

You can use available data fields with available operators and functions.

Data fields

Key	Type	Notes
`http.user_agent.is_ai_bot`	`bool`	Whether the UserAgent string matches the criteria for AI Bots.
`http.user_agent.is_crawler_bot`	`bool`	Whether the UserAgent string matches the criteria for Crawler Bots.
`http.user_agent.string`	`string`	The full UserAgent string.
`http.request.headers`	`http_headers`	The map of HTTP request headers.
`http.request.ip`	`ip`	IP address of the client making the request.
`sdk.platform.name`	`string`	Name of the SDK platform (i.e. one of `js`, `android`, `ios`, `unknown`).
`sdk.version`	`string`	Version of the SDK platform. Example value: `1.2.3`.
`sdk.platform.app_package_name`	`string`	Name of the mobile application bundle, if the request came from a mobile SDK (`android` or `ios`).
`sdk.platform.is_android`	`bool`	Flag indicating if request came from Android device.
`sdk.platform.is_browser`	`bool`	Flag indicating if request came from a web browser.
`sdk.platform.is_ios`	`bool`	Flag indicating if request came from iOS device.
`sdk.platform.is_unknown`	`bool`	Flag indicating if request came from an unknown platform.

Operators

LHS stands for left-hand side of the operation, RHS stands for right-hand side of the operation.

Type	Available operators
Equality	`LHS == RHS` - returns `true` if both sides are equal. `LHS != RHS` - returns `true` if both sides are different.
Numerical	`LHS < RHS` - returns `true` if `LHS` is less than `RHS` `LHS > RHS` - returns `true` if `LHS` is more than `RHS` `LHS <= RHS` - returns `true` if `LHS` is less than or equal to `RHS` `LHS >= RHS` - returns `true` if `LHS` is more than or equal to `RHS` Requires that `LHS` and `RHS` are numerical values.
Logical	`!LHS` - returns the opposite boolean value of `LHS`. `LHS && RHS` - returns `true` if both `LHS` and `RHS` are `true` `LHS \|\| RHS` - returns `true` if either `LHS` or `RHS` are `true` Requires that `LHS` and `RHS` are boolean values.
String	`LHS contains RHS` - returns `true` if `RHS` is a contained in `LHS`. `LHS matches RHS` - returns `true` if `LHS` matches the regular expression in the `RHS`. Requires that `LHS` and `RHS` are strings. For `matches`, `RHS` needs to be a regular expression, and regex pattern should be enclosed with backticks (`).
Array	`LHS[RHS]` - returns the value at index `RHS` in the array `LHS`. Returns `nil` for missing values. Requires that `LHS` is an array, and `RHS` is a number. `LHS in RHS` - returns `true` whether `LHS` is in (or belongs to) `RHS`: `LHS not in RHS` - returns the opposite of `LHS in RHS`. Requires that `RHS` is an array, and `LHS` can be any type.
Object	`LHS[RHS]` - returns the value at index `RHS` in the object `LHS`. Returns `nil` for missing values.` Requires that `LHS` is an array, and `RHS` is a string. `LHS in RHS` - returns `true` whether `LHS` is in (or belongs to) `RHS`:`LHS not in RHS` - returns the opposite of `LHS in RHS`. Requires that `RHS` is an array, and `LHS` can be any type. `LHS.RHS` is equivalent to `LHS[RHS]` where `LHS` is an `object`, and `RHS` is an unquoted `string` literal that can be used as an identifier. Examples: `http.request` is equivalent to `http["request"]`. `http.request.headers.origin.0` produces an error because the unquoted `string` literal `0` cannot be used as an identifier.

Functions and custom data types

Describes additional functions and special data types available during rule evaluation.

Type	Available functions
String	`upper(string) -> string` - transforms the string to all uppercase characters `lower(string) -> string` - - transforms the string to all lowercase characters `starts_with(source string, substring string) -> bool` `ends_with(source string, substring string) -> bool`
Miscellaneous	`len(string\|array\|map\|http_headers) -> int` returns length of the given value
HTTP Headers	The Custom Type `http_headers` behaves similar to a `map`, but it’s keys are normalized to be in MIME Header format in all operations (so usage is case-insensitive), and its values are of type `array` and contain the values for the given header name, preserving the original order. Examples: Check if a header was set: `"cOnTeNt-TyPe" in http.request.headers` Get the first cookie that was set: `http.request.headers["accept"][0]`
IP address and CIDR	The Custom Type `ip` represents an IPv4 or IPv6 address. The Custom Type `cidr` represents an IPv4 or IPv6 CIDR. `cidr(string) cidr` parses an IPv4 or IPv6 CIDR. The `in` operator can be used to check if an `ip` is in a given `cidr`. Example: `http.request.ip in cidr("1.1.1.1/10")`
Semantic Versioning	`semver_compare(s1, s2) -> int` - compares two semver strings, returns `-1` if `s2 < s1`, `1` if `s2 > s1`, or `0` if they are equal `semver_is_valid(string) -> bool` - checks if given string is a valid semver string