116 lines
4.4 KiB
Markdown
116 lines
4.4 KiB
Markdown
# @fastify/merge-json-schema
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__merge-json-schema__ is a javascript library that build a logical product (AND) for multiple [JSON schemas](https://json-schema.org/draft/2020-12/json-schema-core#name-introduction).
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- [Installation](#installation)
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- [Usage](#usage)
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- [API](#api)
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- [mergeSchemas(schemas, options)](#mergeschemasschemas-options)
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- [resolvers](#resolvers)
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- [defaultResolver](#defaultresolver)
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- [License](#license)
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<a name="installation"></a>
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## Installation
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```bash
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npm install @fastify/merge-json-schema
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```
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<a name="usage"></a>
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## Usage
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```javascript
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const assert = require('node:assert')
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const { mergeSchemas } = require('merge-json-schema')
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const schema1 = {
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$id: 'schema1',
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type: 'object',
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properties: {
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foo: { type: 'string', enum: ['foo1', 'foo2'] },
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bar: { type: 'string', minLength: 3 }
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}
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}
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const schema2 = {
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$id: 'schema1',
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type: 'object',
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properties: {
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foo: { type: 'string', enum: ['foo1', 'foo3'] },
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bar: { type: 'string', minLength: 5 }
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},
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required: ['foo']
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}
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const mergedSchema = mergeSchemas([schema1, schema2])
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assert.deepStrictEqual(mergedSchema, {
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$id: 'schema1',
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type: 'object',
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properties: {
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foo: { type: 'string', enum: ['foo1'] },
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bar: { type: 'string', minLength: 5 }
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},
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required: ['foo']
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})
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```
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<a name="api"></a>
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## API
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<a name="merge-schemas"></a>
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#### mergeSchemas(schemas, options)
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Builds a logical conjunction (AND) of multiple [JSON schemas](https://json-schema.org/draft/2020-12/json-schema-core#name-introduction).
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- `schemas` __\<objects[]\>__ - list of JSON schemas to merge.
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- `options` __\<object\>__ - optional options.
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- `resolvers` __\<object\>__ - custom resolvers for JSON schema keywords. Each key is the name of a JSON schema keyword. Each value is a resolver function. See [keywordResolver](#keywordresolver-keyword-values-mergedschema-parentschemas-options).
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- `defaultResolver` __\<function\>__ - custom default resolver for JSON schema keywords. See [keywordResolver](#keywordresolver-keyword-values-mergedschema-parentschemas-options).
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- `onConflict` __\<string\>__ - action to take when a conflict is found. Used by the default `defaultResolver`. Default is `throw`. Possible values are:
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- `throw` - throws an error if found a multiple different schemas for the same keyword.
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- `ignore` - do nothing if found a multiple different schemas for the same keyword.
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- `first` - use the value of the first schema if found a multiple different schemas for the same keyword.
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#### resolvers
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A list of default resolvers that __merge-json-schema__ uses to merge JSON schemas. You can override the default resolvers by passing a list of custom resolvers in the `options` argument of `mergeSchemas`. See [keywordResolver](#keywordresolver-keyword-values-mergedschema-parentschemas-options).
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#### defaultResolver
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A default resolver that __merge-json-schema__ uses to merge JSON schemas. Default resolver is used when no custom resolver is defined for a JSON schema keyword. By default, the default resolver works as follows:
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- If only one schema contains the keyword, the value of the keyword is used as the merged value.
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- If multiple schemas contain the exact same value for the keyword, the value of the keyword is used as the merged value.
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- If multiple schemas contain different values for the keyword, it throws an error.
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#### keywordResolver (keyword, values, mergedSchema, parentSchemas, options)
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__merge-json-schema__ uses a set of resolvers to merge JSON schemas. Each resolver is associated with a JSON schema keyword. The resolver is called when the keyword is found in the schemas to merge. The resolver is called with the following arguments:
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- `keyword` __\<string\>__ - the name of the keyword to merge.
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- `values` __\<any[]\>__ - the values of the keyword to merge. The length of the array is equal to the number of schemas to merge. If a schema does not contain the keyword, the value is `undefined`.
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- `mergedSchema` __\<object\>__ - an instance of the merged schema.
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- `parentSchemas` __\<object[]\>__ - the list of parent schemas.
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- `options` __\<object\>__ - the options passed to `mergeSchemas`.
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The resolver must set the merged value of the `keyword` in the `mergedSchema` object.
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__Example:__ resolver for the `minNumber` keyword.
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```javascript
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function minNumberResolver (keyword, values, mergedSchema) {
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mergedSchema[keyword] = Math.min(...values)
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}
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```
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<a name="license"></a>
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## License
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MIT
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