OneOfRepresents a schema issue produced when a value matches multiple members of a union that is configured to allow exactly one match (oneOf mode).
When to use
Use when you need to detect ambiguous union matches when oneOf validation is
enabled.
Details
astis theUnionAST node.actualis the raw input value (plainunknown).successeslists the AST nodes of each member that accepted the input.- The default formatter renders this as
"Expected exactly one member to match the input <actual>".
modelsAnyOf
Source effect/SchemaIssue.ts:70835 lines
export class class OneOfclass OneOf {
_tag: 'OneOf';
ast: SchemaAST.Union;
actual: unknown;
successes: ReadonlyArray<SchemaAST.AST>;
toString: (this: Issue) => string;
}
Represents a schema issue produced when a value matches multiple members of a union that is
configured to allow exactly one match (oneOf mode).
When to use
Use when you need to detect ambiguous union matches when oneOf validation is
enabled.
Details
ast is the Union AST node.actual is the raw input value (plain unknown).successes lists the AST nodes of each member that accepted the input.- The default formatter renders this as
"Expected exactly one member to match the input <actual>".
OneOf extends class BaseBase {
readonly OneOf._tag: "OneOf"_tag = "OneOf"
/**
* The schema that caused the issue.
*/
readonly OneOf.ast: SchemaAST.Union(property) OneOf.ast: {
_tag: 'Union';
types: ReadonlyArray<A>;
mode: "anyOf" | "oneOf";
encodingChecks: Checks | undefined;
getParser: (recur: (ast: AST) => SchemaParser.Parser) => SchemaParser.Parser;
_rebuild: (recur: (ast: AST) => AST, checks: Checks | undefined, encodingChecks: Checks | undefined) => Union<AST>;
recur: (recur: (ast: AST) => AST) => Union<AST>;
flip: (recur: (ast: AST) => AST) => Union<AST>;
matchPart: (s: string, options: ParseOptions) => LiteralValue | undefined;
getExpected: (getExpected: (ast: AST) => string) => string;
annotations: Schema.Annotations.Annotations | undefined;
checks: Checks | undefined;
encoding: Encoding | undefined;
context: Context | undefined;
toString: () => string;
}
The schema that caused the issue.
ast: import SchemaASTSchemaAST.class Union<A extends SchemaAST.AST = SchemaAST.AST>class Union {
_tag: 'Union';
types: ReadonlyArray<A>;
mode: "anyOf" | "oneOf";
encodingChecks: Checks | undefined;
getParser: (recur: (ast: AST) => SchemaParser.Parser) => SchemaParser.Parser;
_rebuild: (recur: (ast: AST) => AST, checks: Checks | undefined, encodingChecks: Checks | undefined) => Union<AST>;
recur: (recur: (ast: AST) => AST) => Union<AST>;
flip: (recur: (ast: AST) => AST) => Union<AST>;
matchPart: (s: string, options: ParseOptions) => LiteralValue | undefined;
getExpected: (getExpected: (ast: AST) => string) => string;
annotations: Schema.Annotations.Annotations | undefined;
checks: Checks | undefined;
encoding: Encoding | undefined;
context: Context | undefined;
toString: () => string;
}
AST node representing a union of schemas.
Details
types — the member AST nodes.mode — "anyOf" succeeds on the first match (like TypeScript unions);
"oneOf" requires exactly one member to match (fails if multiple do).
During parsing, members are tried in order. An internal candidate index
narrows which members to try based on the runtime type of the input and
discriminant ("sentinel") fields, making large unions efficient.
Example (Inspecting a union AST)
import { Schema, SchemaAST } from "effect"
const schema = Schema.Union([Schema.String, Schema.Number])
const ast = schema.ast
if (SchemaAST.isUnion(ast)) {
console.log(ast.types.length) // 2
console.log(ast.mode) // "anyOf"
}
Union
/**
* The input value that caused the issue.
*/
readonly OneOf.actual: unknownThe input value that caused the issue.
actual: unknown
/**
* The schemas that were successful.
*/
readonly OneOf.successes: ReadonlyArray<SchemaAST.AST>The schemas that were successful.
successes: interface ReadonlyArray<T>ReadonlyArray<import SchemaASTSchemaAST.type AST = SchemaAST.Declaration | SchemaAST.Null | SchemaAST.Undefined | SchemaAST.Void | SchemaAST.Never | SchemaAST.Unknown | SchemaAST.Any | SchemaAST.String | SchemaAST.Number | SchemaAST.Boolean | SchemaAST.BigInt | SchemaAST.Symbol | SchemaAST.Literal | SchemaAST.UniqueSymbol | SchemaAST.ObjectKeyword | SchemaAST.Enum | SchemaAST.TemplateLiteral | SchemaAST.Arrays | SchemaAST.Objects | SchemaAST.Union<...> | SchemaAST.SuspendDiscriminated union of all AST node types.
Details
Every Schema has an .ast property of this type. Use the guard functions
(
isString
,
isObjects
, etc.) to narrow to a specific variant,
then access variant-specific fields.
- All variants share the
Base
fields:
annotations, checks,
encoding, context.
- Discriminate on the
_tag field (e.g. "String", "Objects", "Union").
AST>
constructor(
/**
* The schema that caused the issue.
*/
ast: SchemaAST.Union(parameter) ast: {
_tag: 'Union';
types: ReadonlyArray<A>;
mode: "anyOf" | "oneOf";
encodingChecks: Checks | undefined;
getParser: (recur: (ast: AST) => SchemaParser.Parser) => SchemaParser.Parser;
_rebuild: (recur: (ast: AST) => AST, checks: Checks | undefined, encodingChecks: Checks | undefined) => Union<AST>;
recur: (recur: (ast: AST) => AST) => Union<AST>;
flip: (recur: (ast: AST) => AST) => Union<AST>;
matchPart: (s: string, options: ParseOptions) => LiteralValue | undefined;
getExpected: (getExpected: (ast: AST) => string) => string;
annotations: Schema.Annotations.Annotations | undefined;
checks: Checks | undefined;
encoding: Encoding | undefined;
context: Context | undefined;
toString: () => string;
}
The schema that caused the issue.
ast: import SchemaASTSchemaAST.class Union<A extends SchemaAST.AST = SchemaAST.AST>class Union {
_tag: 'Union';
types: ReadonlyArray<A>;
mode: "anyOf" | "oneOf";
encodingChecks: Checks | undefined;
getParser: (recur: (ast: AST) => SchemaParser.Parser) => SchemaParser.Parser;
_rebuild: (recur: (ast: AST) => AST, checks: Checks | undefined, encodingChecks: Checks | undefined) => Union<AST>;
recur: (recur: (ast: AST) => AST) => Union<AST>;
flip: (recur: (ast: AST) => AST) => Union<AST>;
matchPart: (s: string, options: ParseOptions) => LiteralValue | undefined;
getExpected: (getExpected: (ast: AST) => string) => string;
annotations: Schema.Annotations.Annotations | undefined;
checks: Checks | undefined;
encoding: Encoding | undefined;
context: Context | undefined;
toString: () => string;
}
AST node representing a union of schemas.
Details
types — the member AST nodes.mode — "anyOf" succeeds on the first match (like TypeScript unions);
"oneOf" requires exactly one member to match (fails if multiple do).
During parsing, members are tried in order. An internal candidate index
narrows which members to try based on the runtime type of the input and
discriminant ("sentinel") fields, making large unions efficient.
Example (Inspecting a union AST)
import { Schema, SchemaAST } from "effect"
const schema = Schema.Union([Schema.String, Schema.Number])
const ast = schema.ast
if (SchemaAST.isUnion(ast)) {
console.log(ast.types.length) // 2
console.log(ast.mode) // "anyOf"
}
Union,
/**
* The input value that caused the issue.
*/
actual: unknownThe input value that caused the issue.
actual: unknown,
/**
* The schemas that were successful.
*/
successes: ReadonlyArray<SchemaAST.AST>The schemas that were successful.
successes: interface ReadonlyArray<T>ReadonlyArray<import SchemaASTSchemaAST.type AST = SchemaAST.Declaration | SchemaAST.Null | SchemaAST.Undefined | SchemaAST.Void | SchemaAST.Never | SchemaAST.Unknown | SchemaAST.Any | SchemaAST.String | SchemaAST.Number | SchemaAST.Boolean | SchemaAST.BigInt | SchemaAST.Symbol | SchemaAST.Literal | SchemaAST.UniqueSymbol | SchemaAST.ObjectKeyword | SchemaAST.Enum | SchemaAST.TemplateLiteral | SchemaAST.Arrays | SchemaAST.Objects | SchemaAST.Union<...> | SchemaAST.SuspendDiscriminated union of all AST node types.
Details
Every Schema has an .ast property of this type. Use the guard functions
(
isString
,
isObjects
, etc.) to narrow to a specific variant,
then access variant-specific fields.
- All variants share the
Base
fields:
annotations, checks,
encoding, context.
- Discriminate on the
_tag field (e.g. "String", "Objects", "Union").
AST>
) {
super()
this.OneOf.ast: SchemaAST.Union(property) OneOf.ast: {
_tag: 'Union';
types: ReadonlyArray<A>;
mode: "anyOf" | "oneOf";
encodingChecks: Checks | undefined;
getParser: (recur: (ast: AST) => SchemaParser.Parser) => SchemaParser.Parser;
_rebuild: (recur: (ast: AST) => AST, checks: Checks | undefined, encodingChecks: Checks | undefined) => Union<AST>;
recur: (recur: (ast: AST) => AST) => Union<AST>;
flip: (recur: (ast: AST) => AST) => Union<AST>;
matchPart: (s: string, options: ParseOptions) => LiteralValue | undefined;
getExpected: (getExpected: (ast: AST) => string) => string;
annotations: Schema.Annotations.Annotations | undefined;
checks: Checks | undefined;
encoding: Encoding | undefined;
context: Context | undefined;
toString: () => string;
}
The schema that caused the issue.
ast = ast: SchemaAST.Union(parameter) ast: {
_tag: 'Union';
types: ReadonlyArray<A>;
mode: "anyOf" | "oneOf";
encodingChecks: Checks | undefined;
getParser: (recur: (ast: AST) => SchemaParser.Parser) => SchemaParser.Parser;
_rebuild: (recur: (ast: AST) => AST, checks: Checks | undefined, encodingChecks: Checks | undefined) => Union<AST>;
recur: (recur: (ast: AST) => AST) => Union<AST>;
flip: (recur: (ast: AST) => AST) => Union<AST>;
matchPart: (s: string, options: ParseOptions) => LiteralValue | undefined;
getExpected: (getExpected: (ast: AST) => string) => string;
annotations: Schema.Annotations.Annotations | undefined;
checks: Checks | undefined;
encoding: Encoding | undefined;
context: Context | undefined;
toString: () => string;
}
The schema that caused the issue.
ast
this.OneOf.actual: unknownThe input value that caused the issue.
actual = actual: unknownThe input value that caused the issue.
actual
this.OneOf.successes: ReadonlyArray<SchemaAST.AST>The schemas that were successful.
successes = successes: ReadonlyArray<SchemaAST.AST>The schemas that were successful.
successes
}
}Referenced by 1 symbols