OptionFromUndefinedOr<S>Decodes a required value that may be undefined to a required Option<T>
value.
Details
Decoding maps undefined to None and all other values to Some. Encoding
maps None to undefined and maps Some to its value.
export interface interface OptionFromUndefinedOr<S extends Constraint>Decodes a required value that may be undefined to a required Option<T>
value.
Details
Decoding maps undefined to None and all other values to Some. Encoding
maps None to undefined and maps Some to its value.
Type-level representation returned by
OptionFromUndefinedOr
.
OptionFromUndefinedOr<function (type parameter) S in OptionFromUndefinedOr<S extends Constraint>S extends Constraint> extends interface decodeTo<To extends Constraint, From extends Constraint, RD = never, RE = never>Creates a schema that transforms from a source schema to a target schema.
When to use
Use when decoding should change the schema's decoded type or encoded shape,
with an optional custom bidirectional transformation.
Details
Call it with the target schema to and then pipe the source schema from
into the returned function. The resulting schema decodes from
From["Encoded"] to To["Type"] and encodes from To["Type"] back to
From["Encoded"].
When no transformation is provided, SchemaTransformation.passthrough() is
used, so From["Type"] must already be compatible with To["Encoded"].
The resulting schema combines decoding and encoding services from both
schemas and any custom transformation.
Gotchas
In a custom transformation, decode maps From["Type"] to To["Encoded"]
and is used on the encoding path, while encode maps To["Encoded"] to
From["Type"] and is used on the decoding path.
Example (Transforming strings to numbers with a schema transformation)
import { Schema, SchemaGetter } from "effect"
const NumberFromString = Schema.String.pipe(
Schema.decodeTo(
Schema.Number,
{
decode: SchemaGetter.transform((s) => Number(s)),
encode: SchemaGetter.transform((n) => String(n))
}
)
)
const result = Schema.decodeUnknownSync(NumberFromString)("123")
// result: 123
Type-level representation returned by
decodeTo
.
decodeTo<interface Option<A extends Constraint>Schema for Option<A> values.
Type-level representation returned by
Option
.
Option<interface toType<S extends Constraint>Type-level representation returned by
toType
.
Extracts the type-side schema: sets Encoded to equal the decoded Type,
discarding the encoding transformation path.
toType<function (type parameter) S in OptionFromUndefinedOr<S extends Constraint>S>>, interface UndefinedOr<S extends Constraint>Type-level representation returned by
UndefinedOr
.
Creates a union schema of S | undefined.
UndefinedOr<function (type parameter) S in OptionFromUndefinedOr<S extends Constraint>S>> {
readonly "Rebuild": interface OptionFromUndefinedOr<S extends Constraint>Decodes a required value that may be undefined to a required Option<T>
value.
Details
Decoding maps undefined to None and all other values to Some. Encoding
maps None to undefined and maps Some to its value.
Type-level representation returned by
OptionFromUndefinedOr
.
OptionFromUndefinedOr<function (type parameter) S in OptionFromUndefinedOr<S extends Constraint>S>
}
/**
* Decodes a required value that may be `undefined` to a required `Option<T>`
* value.
*
* **Details**
*
* Decoding maps `undefined` to `None` and all other values to `Some`. Encoding
* maps `None` to `undefined` and maps `Some` to its value.
*
* @category Option
* @since 3.10.0
*/
export function function OptionFromUndefinedOr<
S extends Constraint
>(schema: S): OptionFromUndefinedOr<S>
Decodes a required value that may be undefined to a required Option<T>
value.
Details
Decoding maps undefined to None and all other values to Some. Encoding
maps None to undefined and maps Some to its value.
OptionFromUndefinedOr<function (type parameter) S in OptionFromUndefinedOr<S extends Constraint>(schema: S): OptionFromUndefinedOr<S>S extends Constraint>(schema: S extends Constraintschema: function (type parameter) S in OptionFromUndefinedOr<S extends Constraint>(schema: S): OptionFromUndefinedOr<S>S): interface OptionFromUndefinedOr<S extends Constraint>Decodes a required value that may be undefined to a required Option<T>
value.
Details
Decoding maps undefined to None and all other values to Some. Encoding
maps None to undefined and maps Some to its value.
Type-level representation returned by
OptionFromUndefinedOr
.
OptionFromUndefinedOr<function (type parameter) S in OptionFromUndefinedOr<S extends Constraint>(schema: S): OptionFromUndefinedOr<S>S> {
return const UndefinedOr: UndefinedOrLambda
;<S>(self: S) => UndefinedOr<S>
Type-level representation returned by
UndefinedOr
.
Creates a union schema of S | undefined.
UndefinedOr(schema: S extends Constraintschema).pipe(function decodeTo<Option<toType<S>>, Constraint, never, never>(to: Option<toType<S>>, transformation: {
readonly decode: SchemaGetter.Getter<Option_.Option<A["Encoded"]>, unknown, never>;
readonly encode: SchemaGetter.Getter<unknown, Option_.Option<A["Encoded"]>, never>;
}): (from: Constraint) => decodeTo<Option<toType<S>>, Constraint, never, never> (+1 overload)
Creates a schema that transforms from a source schema to a target schema.
When to use
Use when decoding should change the schema's decoded type or encoded shape,
with an optional custom bidirectional transformation.
Details
Call it with the target schema to and then pipe the source schema from
into the returned function. The resulting schema decodes from
From["Encoded"] to To["Type"] and encodes from To["Type"] back to
From["Encoded"].
When no transformation is provided, SchemaTransformation.passthrough() is
used, so From["Type"] must already be compatible with To["Encoded"].
The resulting schema combines decoding and encoding services from both
schemas and any custom transformation.
Gotchas
In a custom transformation, decode maps From["Type"] to To["Encoded"]
and is used on the encoding path, while encode maps To["Encoded"] to
From["Type"] and is used on the decoding path.
Example (Transforming strings to numbers with a schema transformation)
import { Schema, SchemaGetter } from "effect"
const NumberFromString = Schema.String.pipe(
Schema.decodeTo(
Schema.Number,
{
decode: SchemaGetter.transform((s) => Number(s)),
encode: SchemaGetter.transform((n) => String(n))
}
)
)
const result = Schema.decodeUnknownSync(NumberFromString)("123")
// result: 123
decodeTo(
function Option<A extends Constraint>(
value: A
): Option<A>
Schema for Option<A> values.
Option(const toType: toTypeLambda
;<S>(self: S) => toType<S>
Type-level representation returned by
toType
.
Extracts the type-side schema: sets Encoded to equal the decoded Type,
discarding the encoding transformation path.
toType(schema: S extends Constraintschema)),
import SchemaTransformationSchemaTransformation.function optionFromUndefinedOr<
T
>(): Transformation<
Option.Option<T>,
T | undefined
>
Decodes T | undefined into Option<T> and encodes Option.none() back to
undefined.
When to use
Use when you need a schema transformation to convert API fields that use
undefined for absence to Option.
Details
Decoding maps undefined to Option.none() and non-undefined values to
Option.some(value). Encoding maps Option.none() to undefined and
Option.some(value) to value. The transformation is pure and synchronous.
Example (Converting undefined-or values to an Option)
import { Schema, SchemaTransformation } from "effect"
const schema = Schema.UndefinedOr(Schema.String).pipe(
Schema.decodeTo(
Schema.Option(Schema.String),
SchemaTransformation.optionFromUndefinedOr()
)
)
optionFromUndefinedOr()
))
}