Enhancement: improve validation of custom field values (#5166)

* Support all URI schemes

* Reworks custom field value validation to check and return a 400 error code in more cases and support more URL looking items, not just some basic schemes

* Fixes a spelling error in the message

---------

Co-authored-by: Trenton H <797416+stumpylog@users.noreply.github.com>

src/documents/validators.py

@@ -0,0 +1,29 @@
+from urllib.parse import urlparse
+
+from django.core.exceptions import ValidationError
+from django.utils.translation import gettext_lazy as _
+
+
+def uri_validator(value) -> None:
+    """
+    Raises a ValidationError if the given value does not parse as an
+    URI looking thing, which we're defining as a scheme and either network
+    location or path value
+    """
+    try:
+        parts = urlparse(value)
+        if not parts.scheme:
+            raise ValidationError(
+                _(f"Unable to parse URI {value}, missing scheme"),
+                params={"value": value},
+            )
+        elif not parts.netloc and not parts.path:
+            raise ValidationError(
+                _(f"Unable to parse URI {value}, missing net location or path"),
+                params={"value": value},
+            )
+    except Exception as e:
+        raise ValidationError(
+            _(f"Unable to parse URI {value}"),
+            params={"value": value},
+        ) from e