First invoice implementation.

app/Models/Invoice.php

@@ -3,8 +3,77 @@
 namespace App\Models;
 
 use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+use Illuminate\Database\Eloquent\Relations\HasMany;
 
 class Invoice extends Model
 {
-    //
+    /**
+     * The attributes that are mass assignable.
+     *
+     * @var array<int, string>
+     */
+    protected $fillable = [
+        'user_id',
+        'customer_id',
+        'address_id',
+        'delivery_id',
+        'invoice_number',
+        'type',
+        'status',
+        'sum',
+        'tax',
+    ];
+
+    /**
+     * The attributes that are appended with attribute getters.
+     *
+     * @var string[]
+     */
+    protected $appends = [
+        'created',
+        'number'
+    ];
+
+    /**
+     * Get the invoice number formatted
+     */
+    public function getNumberAttribute(): string
+    {
+        return $this->created_at->format('Y') . '-' . str_pad($this->invoice_number, 5, '0', STR_PAD_LEFT);
+    }
+
+    /**
+     * Get the created_at attribute in local time format.
+     *
+     * @return string
+     */
+    public function getCreatedAttribute(): string
+    {
+        return $this->created_at->format('d.m.Y');
+    }
+    public function user(): BelongsTo
+    {
+        return $this->belongsTo(User::class);
+    }
+
+    public function customer(): BelongsTo
+    {
+        return $this->belongsTo(Customer::class);
+    }
+
+    public function address(): BelongsTo
+    {
+        return $this->belongsTo(Address::class)->withTrashed();
+    }
+
+    public function delivery(): BelongsTo
+    {
+        return $this->belongsTo(Address::class)->withTrashed();
+    }
+
+    public function items(): HasMany
+    {
+        return $this->hasMany(Invoiceitem::class);
+    }
 }