Make minimum hash length configurable.

README.rdoc

@@ -21,10 +21,10 @@ In your model, add a single line.
   end
 
 == Customization
-If you want your hash ids to be different than some other website using the same plugin, you can throw a random string (salt) at hash_id to make it hash out unique ids for your app.
+If you want your hash ids to be different than some other website using the same plugin, you can throw a random string (salt) at hash_id to make it hash out unique ids for your app. You can also customize the minimum hash length.
 
   class Post < ActiveRecord::Base
-    hash_id salt: 'bring_your_own_salt'
+    hash_id salt: 'bring_your_own_salt', min_length: 3
   end
 
 == Limitations

lib/hashids_rails.rb

@@ -5,17 +5,18 @@ def hash_id(options = {})
     require 'hashids'
     extend ClassMethods
     include InstanceMethods
-    cattr_accessor :hash_salt
+    cattr_accessor :hash_salt, :min_hash_length
     self.hash_salt = (options[:salt] || default_salt)
+    self.min_hash_length = (options[:min_length] || 3)
   end
 
-  def self.hide(id, salt)
-    hashids = Hashids.new(salt, 3)
+  def self.hide(id, salt, min_hash_length)
+    hashids = Hashids.new(salt, min_hash_length)
     hashids.encode id
   end
 
-  def self.show(id, salt)
-    hashids = Hashids.new(salt, 3)
+  def self.show(id, salt, min_hash_length)
+    hashids = Hashids.new(salt, min_hash_length)
     decoded = hashids.decode id
     decoded[0] if decoded
   end
@@ -39,7 +40,7 @@ def has_hashed_id?
     end
 
     def dehash_id(hashed_id)
-      HashidsRails.show(hashed_id, self.hash_salt)
+      HashidsRails.show(hashed_id, self.hash_salt, self.min_hash_length)
     end
 
     # Generate a default salt from the Model name
@@ -52,7 +53,7 @@ def default_salt
 
   module InstanceMethods
     def to_param
-      HashidsRails.hide(self.id, self.class.hash_salt)
+      HashidsRails.hide(self.id, self.class.hash_salt, self.class.min_hash_length)
     end
 
     # Override ActiveRecord::Persistence#reload