CEL extensions

This page documents the variables, custom functions, and overloads that Protovalidate adds to Common Expression Language (CEL). All standard rules are defined in CEL expressions and often leverage these Protovalidate-specific CEL extensions.

They are all available in any custom or predefined rule's CEL expression unless otherwise noted.

Variables

this

this refers to the current value. When defining a field rule, this refers to the value of the field. When defining a message rule, this refers to the message itself. Its fields can be accessed via dot notation.

now

now is a google.protobuf.Timestamp. It's computed once per expression: now == now always evaluates to true.

rule

Only available within predefined rules.

rule refers to the value assigned to a predefined rule when used as a field within a Protobuf message.

rules

Only available within predefined rules.

Within a predefined rule, rules is an instance of the underlying Protovalidate rule message being extended. For example, the rules variable made available to a CEL expression for a predefined rule extending StringRules is an instance of the StringRules message itself.

Double functions

Protovalidate adds the following extensions functions to CEL's double type.

isInf

double.isInf() -> bool

Tests whether the double is an infinity.

isNan

double.isNan() -> bool

Tests whether the double is NaN. Returns false when isInf() is true.

Int functions

Protovalidate adds the following extensions functions to CEL's int type.

isInf

int.isInf() -> bool

Tests whether the int is an infinity.

String functions

Protovalidate adds the following extensions functions to CEL's string type.

isEmail

string.isEmail() -> bool

Test whether the string is a valid email address.

isHostAndPort

string.isHostAndPort(bool) -> bool

Test whether the string is a valid host/port pair. The single bool argument is required, and if it's true, the port is also required—otherwise, the port is optional.

isHostname

string.isHostname() -> bool

Test whether the string is a valid hostname.

isIp

string.isIp() -> bool

Test whether the string is a valid IP address in either IPv4 or IPv6.

string.isIp(int) -> bool

Test whether the string is a valid IP address in a specific IP version. Versions other than 0, 4, or 6 always return false.

isIpPrefix

string.isIpPrefix() -> bool

Test whether the string is a valid IP with prefix length.

string.isIpPrefix(int) -> bool

Test whether the string is a valid IP with prefix length in a specific IP version. Versions other than 0, 4, or 6 always return false.

string.isIpPrefix(bool) -> bool

Test whether the string is a valid IP with prefix length and an appropriate network address.

string.isIpPrefix(int, bool) -> bool

Test whether the string is a valid IP with prefix length in a specific IP version and an appropriate network address. IP versions other than 0, 4, or 6 always return false.

isUri

string.isUri()

Tests whether the string is a valid absolute URI.

isUriRef

string.isUriRef() -> bool

Tests whether the string is a valid (absolute or relative) URI.

List functions

Protovalidate adds the following extensions functions to CEL's list type.

unique

list.unique()

Test whether the items in the list are all unique. It can be used with lists of the following types:

• bool
• bytes
• double
• int
• string
• uint

Overloads

Protovalidate overloads the following CEL functions:

contains

bytes.contains(bytes) -> bool

Overload of the CEL standard contains to support bytes.

endsWith

bytes.endsWith(bytes) -> bool

Overload of the CEL standard endsWith to support bytes.

startsWith

bytes.startsWith(bytes) -> bool

Overload of the CEL standard startsWith to support bytes.

Further reading

Learn about all CEL variables and functions within its language definition.