add custom DynamicArrayField to better handle arrays

passbook/lib/fields.py

@@ -0,0 +1,44 @@
+"""passbook lib fields"""
+from itertools import chain
+
+from django import forms
+from django.contrib.postgres.utils import prefix_validation_error
+
+from passbook.lib.widgets import DynamicArrayWidget
+
+
+class DynamicArrayField(forms.Field):
+    """Show array field as a dynamic amount of textboxes"""
+
+    default_error_messages = {"item_invalid": "Item %(nth)s in the array did not validate: "}
+
+    def __init__(self, base_field, **kwargs):
+        self.base_field = base_field
+        self.max_length = kwargs.pop("max_length", None)
+        kwargs.setdefault("widget", DynamicArrayWidget)
+        super().__init__(**kwargs)
+
+    def clean(self, value):
+        cleaned_data = []
+        errors = []
+        value = [x for x in value if x]
+        for index, item in enumerate(value):
+            try:
+                cleaned_data.append(self.base_field.clean(item))
+            except forms.ValidationError as error:
+                errors.append(
+                    prefix_validation_error(
+                        error, self.error_messages["item_invalid"],
+                        code="item_invalid", params={"nth": index}
+                    )
+                )
+        if errors:
+            raise forms.ValidationError(list(chain.from_iterable(errors)))
+        if not cleaned_data and self.required:
+            raise forms.ValidationError(self.error_messages["required"])
+        return cleaned_data
+
+    def has_changed(self, initial, data):
+        if not data and not initial:
+            return False
+        return super().has_changed(initial, data)