From 6c646409785e986343966c347c4ef0c9ad1a287c Mon Sep 17 00:00:00 2001
From: Werner Pieterson <werner@swordfish.co.za>
Date: Tue, 29 Nov 2016 11:07:43 +0200
Subject: [PATCH] Add min_choices validation

---
 multiselectfield/db/fields.py    | 4 +++-
 multiselectfield/forms/fields.py | 5 ++++-
 multiselectfield/validators.py   | 4 ++++
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/multiselectfield/db/fields.py b/multiselectfield/db/fields.py
index 04f05e7..f849740 100644
--- a/multiselectfield/db/fields.py
+++ b/multiselectfield/db/fields.py
@@ -22,7 +22,7 @@ from django.db import models
 from django.utils.text import capfirst
 from django.core import exceptions
 
-from ..forms.fields import MultiSelectFormField, MaxChoicesValidator
+from ..forms.fields import MultiSelectFormField, MinChoicesValidator, MaxChoicesValidator
 from ..utils import get_max_length
 from ..validators import MaxValueMultiFieldValidator
 
@@ -54,6 +54,8 @@ class MultiSelectField(models.CharField):
         super(MultiSelectField, self).__init__(*args, **kwargs)
         self.max_length = get_max_length(self.choices, self.max_length)
         self.validators[0] = MaxValueMultiFieldValidator(self.max_length)
+        if self.min_choices is not None:
+            self.validators.append(MinChoicesValidator(self.min_choices))
         if self.max_choices is not None:
             self.validators.append(MaxChoicesValidator(self.max_choices))
 
diff --git a/multiselectfield/forms/fields.py b/multiselectfield/forms/fields.py
index 6c5fc85..12d4133 100644
--- a/multiselectfield/forms/fields.py
+++ b/multiselectfield/forms/fields.py
@@ -17,13 +17,14 @@
 from django import forms
 
 from ..utils import get_max_length
-from ..validators import MaxValueMultiFieldValidator, MaxChoicesValidator
+from ..validators import MaxValueMultiFieldValidator, MinChoicesValidator, MaxChoicesValidator
 
 
 class MultiSelectFormField(forms.MultipleChoiceField):
     widget = forms.CheckboxSelectMultiple
 
     def __init__(self, *args, **kwargs):
+        self.min_choices = kwargs.pop('min_choices', None)
         self.max_choices = kwargs.pop('max_choices', None)
         self.max_length = kwargs.pop('max_length', None)
         super(MultiSelectFormField, self).__init__(*args, **kwargs)
@@ -31,3 +32,5 @@ class MultiSelectFormField(forms.MultipleChoiceField):
         self.validators.append(MaxValueMultiFieldValidator(self.max_length))
         if self.max_choices is not None:
             self.validators.append(MaxChoicesValidator(self.max_choices))
+        if self.min_choices is not None:
+            self.validators.append(MinChoicesValidator(self.min_choices))
diff --git a/multiselectfield/validators.py b/multiselectfield/validators.py
index bd45332..50c8328 100644
--- a/multiselectfield/validators.py
+++ b/multiselectfield/validators.py
@@ -24,6 +24,10 @@ class MaxValueMultiFieldValidator(validators.MaxLengthValidator):
     code = 'max_multifield_value'
 
 
+class MinChoicesValidator(validators.MinLengthValidator):
+    message = _(u'You must select a minimum of  %(limit_value)d choices.')
+    code = 'min_choices'
+
 class MaxChoicesValidator(validators.MaxLengthValidator):
     message = _(u'You must select a maximum of  %(limit_value)d choices.')
     code = 'max_choices'