(
maxProperties: number,
annotations?: Annotations.Filter
): SchemaAST.Filter<object>Validates that an object contains at most the specified number of properties. This includes both string and symbol keys when counting properties.
Details
JSON Schema:
This check corresponds to the maxProperties constraint in JSON Schema.
Arbitrary:
When generating test data with fast-check, this applies a node-local
maxLength constraint. Object generators interpret it as the final number
of own properties.
export function function isMaxProperties(
maxProperties: number,
annotations?: Annotations.Filter
): SchemaAST.Filter<object>
Validates that an object contains at most the specified number of properties.
This includes both string and symbol keys when counting properties.
Details
JSON Schema:
This check corresponds to the maxProperties constraint in JSON Schema.
Arbitrary:
When generating test data with fast-check, this applies a node-local
maxLength constraint. Object generators interpret it as the final number
of own properties.
isMaxProperties(maxProperties: numbermaxProperties: number, annotations: Annotations.Filter | undefinedannotations?: Annotations.interface Annotations.FilterAnnotations for filter schema nodes (created via Schema.filter). Extends
Augment
with an optional error message, identifier, and metadata.
Filters are intentionally non-parametric to keep them covariant.
Filter) {
maxProperties: numbermaxProperties = var Math: MathAn intrinsic object that provides basic mathematics functionality and constants.
Math.Math.max(...values: number[]): numberReturns the larger of a set of supplied numeric expressions.
max(0, var Math: MathAn intrinsic object that provides basic mathematics functionality and constants.
Math.Math.floor(x: number): numberReturns the greatest integer less than or equal to its numeric argument.
floor(maxProperties: numbermaxProperties))
return const makeFilter: <T>(
filter: (
input: T,
ast: SchemaAST.AST,
options: SchemaAST.ParseOptions
) => FilterOutput,
annotations?: Annotations.Filter | undefined,
abort?: boolean
) => SchemaAST.Filter<T>
Creates a custom validation filter from a predicate function.
Details
The predicate receives the decoded input value, the schema AST, and parse
options, and returns a FilterOutput. Non-success outputs are normalized into
schema issues. The annotations parameter annotates the filter itself; with
the default formatter, failures use message first, expected second, and
<filter> when neither is provided.
When abort is true, parsing stops after this filter fails instead of
collecting later check failures.
Example (Reporting failure at a nested path)
import { Schema } from "effect"
const schema = Schema.Struct({ password: Schema.String, confirmPassword: Schema.String }).check(
Schema.makeFilter((o) =>
o.password === o.confirmPassword
? undefined
: { path: ["password"], issue: "password and confirmPassword must match" }
)
)
console.log(String(Schema.decodeUnknownExit(schema)({ password: "123456", confirmPassword: "1234567" })))
// Failure(Cause([Fail(SchemaError: password and confirmPassword must match
// at ["password"])]))
Example (Reporting multiple failures at once)
import { Schema } from "effect"
const schema = Schema.Struct({ a: Schema.Finite, b: Schema.Finite, c: Schema.Finite }).check(
Schema.makeFilter((o) => {
const issues: Array<Schema.FilterIssue> = []
if (o.a > 0) {
if (o.b <= 0) issues.push({ path: ["b"], issue: "b must be greater than 0" })
if (o.c <= 0) issues.push({ path: ["c"], issue: "c must be greater than 0" })
}
return issues
})
)
console.log(String(Schema.decodeUnknownExit(schema)({ a: 1, b: 0, c: 0 })))
// Failure(Cause([Fail(SchemaError: b must be greater than 0
// at ["b"]
// c must be greater than 0
// at ["c"])]))
makeFilter<object>(
(input: objectinput) => Reflect.function Reflect.ownKeys(target: object): (string | symbol)[]Returns the string and symbol keys of the own properties of an object. The own properties of an object
are those that are defined directly on that object, and are not inherited from the object's prototype.
ownKeys(input: objectinput).Array<T>.length: numberGets or sets the length of the array. This is a number one higher than the highest index in the array.
length <= maxProperties: numbermaxProperties,
{
Annotations.Augment.expected?: string | undefinedHuman-readable description of what a value is expected to satisfy.
Details
For filter and refinement failures, the default formatter uses
message first, then expected, and finally falls back to <filter>.
Use this to name a failed filter in the default message:
Expected <expected>, got <actual>.
expected: `a value with at most ${maxProperties: numbermaxProperties === 1 ? "1 entry" : `${maxProperties: numbermaxProperties} entries`}`,
Annotations.Filter.meta?: Annotations.Meta | undefined(property) Annotations.Filter.meta?: {
_tag: 'isMaxProperties';
maxProperties: number;
}
Optional metadata used to identify or extend the filter with custom data.
meta: {
_tag: "isMaxProperties"_tag: "isMaxProperties",
maxProperties: numbermaxProperties
},
[import SchemaASTSchemaAST.const STRUCTURAL_ANNOTATION_KEY: "~structural"STRUCTURAL_ANNOTATION_KEY]: true,
Annotations.Filter.arbitrary?: Annotations.ToArbitrary.Filter | undefined(property) Annotations.Filter.arbitrary?: {
constraint: { maxLength: number };
}
Optional hints used by arbitrary derivation for this filter.
Details
The same annotation can be attached to a single filter or a
FilterGroup. Group hints apply to the same schema node while child
filters are still collected and checked normally.
arbitrary: {
Annotations.ToArbitrary.Filter.constraint?: Annotations.ToArbitrary.GenerationConstraint | undefined(property) Annotations.ToArbitrary.Filter.constraint?: {
maxLength: number;
}
Annotations.ToArbitrary.GenerationConstraint.maxLength?: number | undefinedmaxLength: maxProperties: numbermaxProperties
}
},
...annotations: Annotations.Filter | undefinedannotations
}
)
}