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technology/tools/JSONPatch.md

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+---
+obj: concept
+website: https://jsonpatch.com
+rfc: https://datatracker.ietf.org/doc/html/rfc6902
+---
+
+# JSONPatch
+JSON Patch is a format for describing changes to a [JSON](../files/JSON.md) document. It can be used to avoid sending a whole document when only a part has changed. When used in combination with the [HTTP](../internet/HTTP.md) PATCH method, it allows partial updates for [HTTP](../internet/HTTP.md) APIs in a standards compliant way.
+
+The patch documents are themselves [JSON](../files/JSON.md) documents.
+A JSON Patch document is just a [JSON](../files/JSON.md) file containing an array of patch operations. The patch operations supported by JSON Patch are “add”, “remove”, “replace”, “move”, “copy” and “test”. The operations are applied in order: if any of them fail then the whole patch operation should abort.
+
+## Simple example
+### The original document
+```json
+{
+  "baz": "qux",
+  "foo": "bar"
+}
+```
+
+### The patch
+```json
+[
+  { "op": "replace", "path": "/baz", "value": "boo" },
+  { "op": "add", "path": "/hello", "value": ["world"] },
+  { "op": "remove", "path": "/foo" }
+]
+```
+
+### The result
+```json
+{
+  "baz": "boo",
+  "hello": ["world"]
+}
+```
+
+## JSON Pointer
+JSON Pointer ([IETF RFC 6901](https://datatracker.ietf.org/doc/html/rfc6901/)) defines a string format for identifying a specific value within a [JSON](../files/JSON.md) document. It is used by all operations in JSON Patch to specify the part of the document to operate on.
+
+A JSON Pointer is a string of tokens separated by `/` characters, these tokens either specify keys in objects or indexes into arrays. For example, given the [JSON](../files/JSON.md)
+```json
+{
+  "biscuits": [
+    { "name": "Digestive" },
+    { "name": "Choco Leibniz" }
+  ]
+}
+```
+
+`/biscuits` would point to the array of biscuits and `/biscuits/1/name` would point to `"Choco Leibniz"`.
+
+To point to the root of the document use an empty string for the pointer. The pointer `/` doesn’t point to the root, it points to a key of `""` on the root (which is totally valid in [JSON](../files/JSON.md)).
+
+If you need to refer to a key with `~` or `/` in its name, you must escape the characters with `~0` and `~1` respectively. For example, to get `"baz"` from `{ "foo/bar~": "baz" }` you’d use the pointer `/foo~1bar~0`.
+
+Finally, if you need to refer to the end of an array you can use `-` instead of an index. For example, to refer to the end of the array of biscuits above you would use `/biscuits/-`. This is useful when you need to insert a value at the end of an array.
+
+## Operations
+### Add
+```json
+{ "op": "add", "path": "/biscuits/1", "value": { "name": "Ginger Nut" } }
+```
+
+Adds a value to an object or inserts it into an array. In the case of an array, the value is inserted before the given index. The `-` character can be used instead of an index to insert at the end of an array.
+
+### Remove
+```json
+{ "op": "remove", "path": "/biscuits" }
+```
+
+Removes a value from an object or array.
+```json
+{ "op": "remove", "path": "/biscuits/0" }
+```
+
+Removes the first element of the array at `biscuits` (or just removes the “0” key if `biscuits` is an object)
+
+### Replace
+```json
+{ "op": "replace", "path": "/biscuits/0/name", "value": "Chocolate Digestive" }
+```
+
+Replaces a value. Equivalent to a "remove" followed by an "add".
+
+### Copy
+```json
+{ "op": "copy", "from": "/biscuits/0", "path": "/best_biscuit" }
+```
+
+Copies a value from one location to another within the [JSON](../files/JSON.md) document. Both `from` and `path` are JSON Pointers.
+
+### Move
+```json
+{ "op": "move", "from": "/biscuits", "path": "/cookies" }
+```
+
+Moves a value from one location to the other. Both `from` and `path` are JSON Pointers.
+
+### Test
+```json
+{ "op": "test", "path": "/best_biscuit/name", "value": "Choco Leibniz" }
+```
+
+Tests that the specified value is set in the document. If the test fails, then the patch as a whole should not apply.