Build the stuff for payments.

app/Models/Invoice.php

@@ -38,8 +38,6 @@ class Invoice extends Model
 
     /**
      * Get the invoice state as translated string.
-     *
-     * @return string
      */
     public function getLocalizedStateAttribute(): string
     {
@@ -56,35 +54,57 @@ class Invoice extends Model
 
     /**
      * Get the created_at attribute in local time format.
-     *
-     * @return string
      */
     public function getCreatedAttribute(): string
     {
         return $this->created_at->format('d.m.Y');
     }
+
+    /**
+     * Get the user, that has created the invoice.
+     */
     public function user(): BelongsTo
     {
         return $this->belongsTo(User::class);
     }
 
+    /**
+     * Get the invoice's customer.
+     */
     public function customer(): BelongsTo
     {
         return $this->belongsTo(Customer::class);
     }
 
+    /**
+     * Get the invoice's address.
+     */
     public function address(): BelongsTo
     {
         return $this->belongsTo(Address::class)->withTrashed();
     }
 
+    /**
+     * Get the invoice's delivery address.
+     */
     public function delivery(): BelongsTo
     {
         return $this->belongsTo(Address::class)->withTrashed();
     }
 
+    /**
+     * Get the items (invoice positions) of this invoice.
+     */
     public function items(): HasMany
     {
         return $this->hasMany(Invoiceitem::class);
     }
+
+    /**
+     * Get the payments for the invoice
+     */
+    public function payments(): HasMany
+    {
+        return $this->hasMany(Payment::class);
+    }
 }