feat: Add prefix and max_length to the Django field

CHANGELOG.md

@@ -1,7 +1,7 @@
 # Changelog
 
 
-## Unreleased
+## v1.0.6 (2021-11-08)
 
 ### Fixes
 

README.md

@@ -163,14 +163,21 @@ from shortuuid.django_fields import ShortUUIDField
 
 class MyModel(models.Model):
     # A primary key ID of length 16 and a short alphabet.
-    id = ShortUUIDField(length=16, alphabet="abcdefg1234", primary_key=True)
+    id = ShortUUIDField(
+        length=16,
+        max_length=40,
+        prefix="id_",
+        alphabet="abcdefg1234",
+        primary_key=True,
+    )
+
     # A short UUID of length 22 and the default alphabet.
     api_key = ShortUUIDField()
 ```
 
-The field is the same as the `CharField`, with `max_length` replaced with `length`, an
-`alphabet` argument added and the `default` argument removed. Everything else is exactly
-the same, e.g. `index`, `help_text`, etc.
+The field is the same as the `CharField`, with a `length` argument (the length of the
+ID), an `alphabet` argument, and the `default` argument removed. Everything else is
+exactly the same, e.g. `index`, `help_text`, `max_length`, etc.
 
 
 Compatibility note

shortuuid/django_fields.py

@@ -8,19 +8,28 @@ class ShortUUIDField(models.CharField):
     description = _("A short UUID field.")
 
     def __init__(self, *args, **kwargs):
-        self.length = kwargs["max_length"] = kwargs.pop("length", 22)
+        self.length = kwargs.pop("length", 22)
+        self.prefix = kwargs.pop("prefix", "")
+
+        if "max_length" not in kwargs:
+            # If `max_length` was not specified, set it here.
+            kwargs["max_length"] = self.length
+
         self.alphabet = kwargs.pop("alphabet", None)
         kwargs["default"] = self._generate_uuid
 
         super().__init__(*args, **kwargs)
 
     def _generate_uuid(self):
         """Generate a short random string."""
-        return ShortUUID(alphabet=self.alphabet).random(length=self.length)
+        return self.prefix + ShortUUID(alphabet=self.alphabet).random(
+            length=self.length
+        )
 
     def deconstruct(self):
         name, path, args, kwargs = super().deconstruct()
         kwargs["alphabet"] = self.alphabet
-        kwargs["length"] = kwargs.pop("max_length")
+        kwargs["length"] = self.length
+        kwargs["prefix"] = self.prefix
         kwargs.pop("default", None)
         return name, path, args, kwargs