Upsert with partial index

[sakairyota]

The combination of upsert and partial index is not working.
I think this is not a bug, but it may worth to support.
Reproduction information is below.

Versions:
larave/franework: 10.9.0
tpetry/laravel-postgresql-enhanced: 0.29.0

Migration file:

    public function up(): void
    {
        Schema::create('items', function (Blueprint $table) {
            $table->id();
            $table->string('code');
            $table->timestamps();
            $table->softDeletes();

            $table->uniqueIndex(['code'])
                ->where(fn (Builder $condition) => $condition->whereNull('deleted_at'));
        });
    }

Model:

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\SoftDeletes;

class Item extends Model
{
    use SoftDeletes;

    protected $fillable = ['code'];
}

Source Code (I ran it in tinker)

use App\Models\Item;
Item::upsert(['code' => 'item1'], ['code']);

Then an exception occuerd
Illuminate\Database\QueryException SQLSTATE[42P10]: Invalid column reference: 7 ERROR: there is no unique or exclusion constraint matching the ON CONFLICT specification (Connection: pgsql, SQL: insert into "items" ("code", "created_at", "updated_at") values (item1, 2023-04-26 12:51:09, 2023-04-26 12:51:09) on conflict ("code") do update set "code" = "excluded"."code", "updated_at" = "excluded"."updated_at").

When I wrote on conflict with where manually, it was working. So we have to insert where before do update to upsert with partial index.

DB::statement('INSERT INTO "items" ("code", "created_at", "updated_at") VALUES (\'item1\', NOW(), NOW()) ON CONFLICT ("code") WHERE deleted_at IS NULL DO UPDATE SET "code" = "excluded"."code", "updated_at" = "excluded"."updated_at"');
# = true

---

But in compileUpsert method In Illuminate\Database\Query\Grammars\PostgresGrammar in laravel/framework, on conflict and do update set is wrote in single line and it's not customizable.

$sql .= ' on conflict ('.$this->columnize($uniqueBy).') do update set ';

If you support this feature, I think we have to override compileUpsert in PostgresGrammar.

[sakairyota]

After writing the issue, I noticed that this problem is not directly related this library.
But it may still worth to support.