marys
111 lines
3.3 KiB
Markdown
111 lines
3.3 KiB
Markdown
Tiny Merge Patch
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================
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[](https://travis-ci.org/QuentinRoy/tiny-merge-patch)
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[](https://codecov.io/gh/QuentinRoy/tiny-merge-patch)
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[](https://david-dm.org/quentinroy/tiny-merge-patch)
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[](https://david-dm.org/quentinroy/tiny-merge-patch?type=dev)
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An implementation of the JSON Merge Patch
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[RFC 7396](http://tools.ietf.org/html/rfc7396): a standard format used to
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describe modifications to JSON documents.
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This library complies with the functional programming style: it does not mutate
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the original target, but recycles what it can.
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`tiny-merge-patch` passes all [RFC 7396](http://tools.ietf.org/html/rfc7396) tests.
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## Install
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Install the current version (and save it as a dependency):
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### npm
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```sh
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npm install tiny-merge-patch --save
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```
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## Import
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### CommonJs with node
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```js
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// Fetch `apply` from the module.
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const mergePatch = require('tiny-merge-patch').apply;
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```
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### ES modules in the browser
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```js
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// `apply` is also the default export.
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import mergePatch from 'https://unpkg.com/tiny-merge-patch/esm/index.js'
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```
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## Usage
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```js
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// Original document / object.
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const doc = {
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a: 'b',
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c: { d: 'e', f: 'g' },
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h: { i: 0 }
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};
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// JSON merge patch to apply.
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const patch = {
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a: 'z',
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c: { f: null } // null marks deletions.
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};
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// Apply the patch.
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const patchedDoc = mergePatch(doc, patch);
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// tiny-merge-patch complies with the RFC specification.
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assert.deepEqual(patchedDoc, {
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a: 'z',
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c: { d: 'e' },
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h: { i: 0 },
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});
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// Additionally, it does not mutate the original document...
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assert(patchedDoc !== doc);
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// ...nor its content...
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assert(patchedDoc.c !== doc.c);
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// ...but recycles what it can.
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assert(patchedDoc.h === doc.h);
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```
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## Alternatives
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- [`json-merge-patch`](https://github.com/pierreinglebert/json-merge-patch) (from which this library is forked)
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- [`merge-patch`](https://github.com/krisnye/merge-patch)
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- [`json8-merge-patch`](https://github.com/JSON8/merge-patch)
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All are in-place.
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To avoid mutations of the original object, one can deep-clone beforehand, but it can be expensive.
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At the contrary, `tiny-merge-patch` does not alter any of its arguments—but
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recycles what it can.
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Recycling also allows efficient strict identity-based memoization
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(used by [React](https://reactjs.org)'s [PureComponent](https://reactjs.org/docs/react-api.html#reactpurecomponent) for example).
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All of the above libraries also embed additional functionalities, such as patch generation from two objects or merge of patches.
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`tiny-merge-patch` only focuses on the IETF standard and on patch applications.
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(None of the above libraries are particularly big.
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Still, `tiny-merge-patch` is smaller if you only need to apply patches.
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It is also worth mentioning that unlike
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[JSON patches](https://tools.ietf.org/html/rfc6902), there is no way to
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implement merge of merge patches that reliably preserves deletion.)
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- [`immutable-merge-patch`](https://www.npmjs.com/package/immutable-merge-patch)
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JSON merge patch implementation for [Immutable.js](https://facebook.github.io/immutable-js/).
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# License
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[MIT](./LICENSE)
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