rego_type_error: function {name} has arity n, got m argument(s)
Arity is a term used to describe the number of arguments a function takes. This error happens when a user-defined function is called with an unexpected number of arguments - the wrong arity.
This message is only shown for user defined functions, not for Rego's built-in functions. For errors
containing arity mismatch see this section.
| Stage | Category | Message |
|---|---|---|
compilation | rego_type_error | {name} has arity n, got m argument(s)` |
Examples
In the following example, the user-defined function is_authorized function is called with one argument,
but it takes two:
package policy
import future.keywords.if
import future.keywords.in
default is_authorized(_, _) := false
is_authorized(user_id, resource) if {
# implementation details
}
default allow := false
allow := is_authorized(input)
When compiled, this will result in the following error:
1 error occurred: policy.rego:16: rego_type_error: function data.policy.is_authorized has arity 2, got 1 argument
How To Fix It
In order to find the function that's being called with the wrong arity, you first need to find the line number
in the error message - 16 in the example above. On that line, we need to update the function call to pass the
correct number of arguments. The example above might be fixed like so:
package policy
import future.keywords.if
import future.keywords.in
default is_authorized(_, _) := false
is_authorized(user_id, resource) if {
# implementation details
}
default allow := false
allow := is_authorized(input.user_id, input.resource) # pass two arguments
Community
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