ValidationRule

Concept: Objects, Records, and Fields →

A single entry in an object’s rules: block: a named boolean condition that every record of the object must satisfy.

Carries a human-readable label, a formula expression evaluated as a boolean predicate, and optional fields controlling the violation message and which field an error is attributed to.

Properties

Property	Type	Required/Default	Constraints	Meaning
label	string	Required		Human-readable name for the rule, shown in error displays.
expression	string	Required		The rule’s boolean formula expression, e.g. "score >= 0".
message	string	Optional		The message shown to the caller when a record violates this rule, e.g. "Score cannot be negative.".
field	string	Optional	min length 1; max length 63; pattern ^[a-z][a-zA-Z0-9]*$	Pins which field a violation of this rule is attributed to in the API error payload.

label

Human-readable name for the rule, shown in error displays.

Distinct from the rule’s key in the rules: map — the label may contain spaces and punctuation. Purely informational; not used to identify the rule internally.

expression

The rule’s boolean formula expression, e.g. "score >= 0". See the formula language reference for supported syntax.

Must be non-empty and must evaluate to a boolean. An empty expression, one that fails to compile, or one that evaluates to a non-boolean type each produce a compile-time diagnostic.

message

The message shown to the caller when a record violates this rule, e.g. "Score cannot be negative.". Absent by default.

When absent, a generic message derived from label is used instead. When set, this string is returned verbatim in the API error payload.

field

Pins which field a violation of this rule is attributed to in the API error payload. Absent by default.

When absent, attribution is derived automatically: an expression that references exactly one field on this object attributes to that field; anything else (multiple fields, a cross-object reference, or a constant expression) attributes to the object as a whole (__object). When set, the field must exist on the object and appear in the expression — an invalid pin produces a compile-time diagnostic and falls back to whole-object attribution.

Example

{
  "expression": "example",
  "label": "example"
}