lib/popcorn: introduce UniqueField stub validator

Signed-off-by: Alexandre Terrasa <alexandre@moz-code.org>

diff --git a/lib/popcorn/pop_validation.nit b/lib/popcorn/pop_validation.nit
index 8f1b041..aebbc93 100644 (file)
--- a/lib/popcorn/pop_validation.nit
+++ b/lib/popcorn/pop_validation.nit
@@ -729,3 +729,42 @@ class URLField
 
        redef var re = "^(http|https):\\/\\/[a-zA-Z0-9\\-_]+(\\.[a-zA-Z0-9\\-_]+)+([a-zA-Z0-9\\-\\.,@?^=%&:/~\\+#]*[a-zA-Z0-9\\-\\@?^=%&/~\\+#])?".to_re
 end
+
+# Check if a field value is already used
+#
+# This class provides a stub validator for fields that should contain a unique value along an
+# application (typically logins or ids).
+#
+# Here an example that uses a `Repository` if an email is unique:
+# ~~~nitish
+# class UniqueEmailField
+#      super UniqueField
+#
+#      var users: UsersRepository
+#
+#      redef fun check_unicity(v, field, val) do
+#              var user = users.find_by_email(val)
+#              if user != null then
+#                      v.validation.add_error(field, "Email `{val}` already used")
+#                      return false
+#              end
+#              return true
+#      end
+# end
+# ~~~
+class UniqueField
+       super StringField
+
+       # Check if `val` is already used somewhere
+       #
+       # You must redefine this method to handle your own validation.
+       fun check_unicity(v: ObjectValidator, field, val: String): Bool is abstract
+
+       redef fun validate_field(v, obj) do
+               if not super then return false
+               var val = obj.get_or_null(field)
+               if not val isa String then return false
+               if not check_unicity(v, field, val) then return false
+               return true
+       end
+end