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32 lines
1.0 KiB
32 lines
1.0 KiB
/** |
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Create a type that makes the given keys optional. The remaining keys are kept as is. The sister of the `SetRequired` type. |
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Use-case: You want to define a single model where the only thing that changes is whether or not some of the keys are optional. |
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@example |
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``` |
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import {SetOptional} from 'type-fest'; |
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type Foo = { |
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a: number; |
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b?: string; |
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c: boolean; |
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} |
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type SomeOptional = SetOptional<Foo, 'b' | 'c'>; |
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// type SomeOptional = { |
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// a: number; |
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// b?: string; // Was already optional and still is. |
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// c?: boolean; // Is now optional. |
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// } |
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``` |
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*/ |
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export type SetOptional<BaseType, Keys extends keyof BaseType = keyof BaseType> = |
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// Pick just the keys that are not optional from the base type. |
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Pick<BaseType, Exclude<keyof BaseType, Keys>> & |
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// Pick the keys that should be optional from the base type and make them optional. |
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Partial<Pick<BaseType, Keys>> extends |
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// If `InferredType` extends the previous, then for each key, use the inferred type key. |
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infer InferredType |
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? {[KeyType in keyof InferredType]: InferredType[KeyType]} |
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: never;
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