orbit4-5/app/views/admin/groups/newpost.html.erb

<%= form_for @grouppost, :url => admin_group_createpost_path(@group), :html => { :multipart => true , :class=>"form-horizontal main-forms"} do |f| %>
	<fieldset>
		<%= render :partial => "post_form", locals: {f: f} %>
	</fieldset>
<% end %>
<script type="text/javascript">
	Dropzone.autoDiscover = false;
	var image_id_panel = $("#image_ids");
	var groupImageDropzone = new Dropzone("div#group-post-images", {
		url :  "/admin/posts/image",
		previewsContainer : "#group-post-images-container",
		paramName : "group_post_image[image]",
		clickable : true,
		autoProcessQueue : false,
		addRemoveLinks : true,
		uploadMultiple : false,
	    accept: function(file, done) {
	      var regex = new RegExp(/(\.|\/)(gif|jpe?g|png)$/i)
	      if(regex.test(file.name)){
	      	done();
	      }else{
	      	this.removeFile(file);
	      }
	    }
	})

	$(".upload_image_btn").on("click",function(){
		$(".dropzone a.dz-remove").remove();
		doUpload();
		return false;
	})

	$(".remove_image_btn").on("click",function(){
		groupImageDropzone.removeAllFiles();
		return false;
	})

	groupImageDropzone.on("success",function(file,data){
		image_id_panel.append("<input type='hidden' name='group_post[group_post_images][]' value='" + data.id + "' />");
	})
	groupImageDropzone.on("sending",function(file,xhr,obj){
		obj.append("authenticity_token",$("form#new_group_post input[name=authenticity_token]").val());
	})

	var doUpload = function(){
		groupImageDropzone.processQueue();
		groupImageDropzone.on("complete", function(file) {
			var filesCount = groupImageDropzone.getQueuedFiles().length;
			if(filesCount > 0){
				doUpload();
			}
		});
	}

	$("form#new_group_post").submit(function(){
		if(groupImageDropzone.getQueuedFiles().length > 0){
			alert("Please upload all the files or remove them before submitting a post.");
			return false;
		}else{
			return true;
		}
	})

</script>