# JSON Pointers

HTML: [altophp.com/json-patch/pointers](https://altophp.com/json-patch/pointers/)

JSON Patch paths follow RFC 6901. The empty string addresses the document root;
every other pointer starts with `/`.

```php
use Alto\JsonPatch\JsonPatch;

$document = [
    'users' => [
        ['name' => 'Alice'],
    ],
];

echo JsonPatch::get($document, '/users/0/name');
```

List indices are decimal integers without leading zeros. The `-` segment is
valid only for appending with an `add` operation.

## Escape property names

Within one segment, `~1` represents `/` and `~0` represents `~`:

```php
<?php

require __DIR__.'/vendor/autoload.php';

use Alto\JsonPatch\JsonPatch;

$document = ['a/b' => ['~key' => 'value']];
echo JsonPatch::get($document, '/a~1b/~0key'), "\n";
```

Output:

```text
value
```

Invalid escape sequences raise `JsonPatchException`. Escape each property-name
segment separately: replace `~` with `~0`, then `/` with `~1`. Do not escape the
slashes that separate segments. For missing paths, inspect the actual container
and list indices before applying the operation.

## Inspect a pointer

```php
use Alto\JsonPatch\Pointer;

$pointer = Pointer::parse('/users/0/name');

$pointer->segments();          // ['users', '0', 'name']
$pointer->parent()->toString(); // /users/0
$pointer->last();              // name
$pointer->isRoot();            // false
```

Parsed pointers are cached internally. Application code normally uses
`JsonPatch` methods directly; `Pointer` is useful when another component must
inspect or compose the same path model.

---

Previous: [Operations](https://altophp.com/json-patch/operations.md)
Next: [Generating patches](https://altophp.com/json-patch/diffing.md)

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ALTO\JSON PATCH: [altophp.com/json-patch](https://altophp.com/json-patch/)
ALTO(PHP): [altophp.com](https://altophp.com/)