Eloquent Models

They add a correlated subselect to the SELECT list, so each parent row comes back with an aggregate attribute and no related models are loaded: tags_count, purchases_sum_amount, or a boolean comments_exists. An 'as' alias renames it.

hasManyThrough() and hasOneThrough() reach models two has-type hops away through an intermediate model in one query. After the final and intermediate classes, the third argument is the key on the intermediate table and the fourth the key on the final table.

Both traits make a model define prunable(), a query for rows to remove, and model:prune runs it. Prunable loads matches in chunks and deletes each model, calling pruning() and firing events; MassPrunable deletes by query, faster but with no events or hook.

The column stores ciphertext from Laravel's encrypter, keyed by APP_KEY; Eloquent decrypts on read and encrypts on write. The payload is long, so use a TEXT column, and SQL can no longer filter, sort, index or join on it.

With $guarded = [] every posted key that names a column is written, so a user can add is_vip or user_id to the request. Harden it with a $fillable allow-list, explicit input arrays, server-set privileged fields and strict discarding in development.

Use chunkById() or lazyById() when the loop updates rows it filters on, since offset-based chunk() and lazy() then skip rows. cursor() runs one query and holds one model but cannot eager load, and the driver may still buffer the result.

upsert() inserts or updates a whole batch in one statement, where updateOrCreate() costs a select plus a write per row. It sets timestamps but skips model events, casts, mutators and mass-assignment filtering, and needs a unique index on uniqueBy.

Model::automaticallyEagerLoadRelationships() turns a lazy load on any model from a collection into one batched load for every model in that collection. It fixes plain N+1 loops, but not constrained loads, counts, relation method calls or one-by-one fetches.

A missing tags field becomes [], and sync([]) detaches every tag. sync() also runs several statements without a transaction, so a bad ID can fail after links are deleted. Sync only when the field is present, validate IDs, use syncOrFail().

Polymorphic relations store a type and an id on the child so one model can belong to several parent types. enforceMorphMap() stores short aliases instead of class names and throws for unmapped models, so renames and new models cannot corrupt the type column.

DB::table() and raw SQL skip the scope; a builder-level forceDelete() runs with no global scopes; a scope reading auth() finds no user in jobs and commands; and withoutGlobalScopes() calls spread. Pass firm context explicitly, fail closed without it, and test cross-firm access.

The $attributes property gives new model instances default column values. They sit in the raw attributes array without passing through casts or mutators, so a JSON-cast column needs the string '[]', not a PHP array.

Eager-loaded children do not get their parent set, so $comment->post inside a loop over $post->comments lazy loads the post again. chaperone() sets that inverse relation on each child after the query, with no extra query.

latestOfMany(), oldestOfMany() and ofMany() turn a hasOne into the single latest, oldest or best row of a has-many, resolved by a grouped subquery join. Unlike latest()->first(), it is a real relation that can be eager loaded for many parents at once.