+) Allow to set select2.minimumInputLength from AjaxSelect2Widget.

   Default to 1

flask_admin/model/widgets.py

@@ -27,6 +27,7 @@ class AjaxSelect2Widget(object):
     def __call__(self, field, **kwargs):
         kwargs['data-role'] = u'select2-ajax'
         kwargs['data-url'] = url_for('.ajax_lookup', name=field.loader.name)
+        kwargs['data-minimum-input-length'] = int( getattr(field, 'minimum_input_length', 1) )
 
         allow_blank = getattr(field, 'allow_blank', False)
         if allow_blank and not self.multiple:

flask_admin/static/admin/js/form.js

@@ -11,7 +11,7 @@
 
         var opts = {
           width: 'resolve',
-          minimumInputLength: 1,
+          minimumInputLength: $el.attr('data-minimum-input-length'),
           placeholder: 'data-placeholder',
           ajax: {
             url: $el.attr('data-url'),
@@ -93,6 +93,8 @@
                 if ($el.attr('data-allow-blank'))
                     opts['allowClear'] = true;
 
+                opts['minimumInputLength'] = $el.attr('data-minimum-input-length');
+
                 if ($el.attr('data-tags')) {
                     $.extend(opts, {
                         tokenSeparators: [','],