Link Fieldtype recursion

[mytchallb]

Bug description

When trying to fetch an entry which contains a link fieldtype set to itself there is infinite recursion.
Suggest adding a limit or show a warning.

How to reproduce

Statamic 6, fresh install.
Created a link fieldset for homepage blueprint.
Set entry to homepage.

Created api route to return homepage:

Route::get('/test', function () {
    $entry = Entry::query()->where('slug', 'home')->first();
    return response()->json($entry);
});

Logs

Maximum call stack size of 8339456 bytes (zend.max_allowed_stack_size - zend.reserved_stack_size) reached. Infinite recursion?

Environment

Environment
Laravel Version: 12.63.0
PHP Version: 8.4.22
Composer Version: 2.10.2
Environment: local
Debug Mode: ENABLED
Maintenance Mode: OFF
Timezone: UTC
Locale: en

Cache
Config: NOT CACHED
Events: NOT CACHED
Routes: NOT CACHED
Views: CACHED

Drivers
Broadcasting: log
Cache: file
Database: sqlite
Logs: stack / single
Mail: smtp
Queue: sync
Session: file

Storage
public/storage: NOT LINKED

Statamic
Addons: 0
License Key: Not set
Sites: 1
Stache Watcher: Enabled (auto)
Static Caching: Disabled
Version: 6.24.2 PRO

Installation

Fresh statamic/statamic site via CLI

Additional details

Using DDEV

[mynetx]

Looked into this. The recursion happens when the entry gets turned into JSON.

The Link field wraps the linked entry in a small helper class (ArrayableLink). That class has two ways of converting itself to data:

• jsonSerialize(): safe, only returns a few basic fields (id, title, url, etc.)
• toArray(): unsafe, tries to fully expand the whole entry again

The problem: json_encode() on an entry calls toArray(), not jsonSerialize(). So the safe path never actually gets used. If a Link points back at its own entry, this keeps expanding the same entry forever.

Why does Link skip the safety net other relationship fields have? It's tagged with the "relationship" category, but it's never marked internally as an actual relationship field, so it misses the shallow-nesting guard that fields like Entries already get.

Two ways to fix it:

1. Make toArray() behave like jsonSerialize() already does (shallow). Small change, but it changes what a Link field returns when nested in API output.
2. Properly mark Link as a relationship field, so it gets the same shallow-nesting behavior as the others.

Either works, just changes the output shape a bit. Let me know which direction you'd prefer and I'll put together a PR.

[mytchallb]

Nice, sounds like the 2nd solution fits in with the rest of the CMS behaviour

[o1y]

It think this is a duplicate of:

#14696
#9105

[duncanmcclean]

Closing in favour of #9105