# ApplyDefaultOptions

`type` in `services` · v0.8.2

<https://docs.seedcord.org/packages/services/0.8.2/types/apply-default-options-2>

Merges user specified options with default options.

## Examples

```ts
type PathsOptions = {maxRecursionDepth?: number; leavesOnly?: boolean};
type DefaultPathsOptions = {maxRecursionDepth: 10; leavesOnly: false};
type SpecifiedOptions = {leavesOnly: true};

type Result = ApplyDefaultOptions<PathsOptions, DefaultPathsOptions, SpecifiedOptions>;
//=> {maxRecursionDepth: 10; leavesOnly: true}
```

```ts
// Complains if default values are not provided for optional options

type PathsOptions = {maxRecursionDepth?: number; leavesOnly?: boolean};
type DefaultPathsOptions = {maxRecursionDepth: 10};
type SpecifiedOptions = {};

type Result = ApplyDefaultOptions<PathsOptions, DefaultPathsOptions, SpecifiedOptions>;
//                                              ~~~~~~~~~~~~~~~~~~~
// Property 'leavesOnly' is missing in type 'DefaultPathsOptions' but required in type '{ maxRecursionDepth: number; leavesOnly: boolean; }'.
```

```ts
// Complains if an option's default type does not conform to the expected type

type PathsOptions = {maxRecursionDepth?: number; leavesOnly?: boolean};
type DefaultPathsOptions = {maxRecursionDepth: 10; leavesOnly: 'no'};
type SpecifiedOptions = {};

type Result = ApplyDefaultOptions<PathsOptions, DefaultPathsOptions, SpecifiedOptions>;
//                                              ~~~~~~~~~~~~~~~~~~~
// Types of property 'leavesOnly' are incompatible. Type 'string' is not assignable to type 'boolean'.
```

```ts
// Complains if an option's specified type does not conform to the expected type

type PathsOptions = {maxRecursionDepth?: number; leavesOnly?: boolean};
type DefaultPathsOptions = {maxRecursionDepth: 10; leavesOnly: false};
type SpecifiedOptions = {leavesOnly: 'yes'};

type Result = ApplyDefaultOptions<PathsOptions, DefaultPathsOptions, SpecifiedOptions>;
//                                                                   ~~~~~~~~~~~~~~~~
// Types of property 'leavesOnly' are incompatible. Type 'string' is not assignable to type 'boolean'.
```

## Declaration

```ts
type ApplyDefaultOptions<Options extends object, Defaults extends Simplify<Omit<Required<Options>, RequiredKeysOf<Options>> & Partial<Record<RequiredKeysOf<Options>, never>>>, SpecifiedOptions extends Options> = _ApplyDefaultOptions<Options, Defaults, SpecifiedOptions> extends infer Result extends Required<Options> // `extends Required<Options>` ensures that `ApplyDefaultOptions<SomeOption, ...>` is always assignable to `Required<SomeOption>` ? Result : never
```