Get Rid of Your Admin Gem

After using the two most popular Rails admin gems ActiveAdmin and RailsAdmin I have been increasingly disillusioned with their overall utility. While they both provide a quick way to put up a pretty interface to the various models in your system, they also come with their own baggage: application bloat and inflexibility amongst them. Eventually you may find it necessary to modify their configurations and inner workings to the point where it might have been easier to just build things from scratch in the first place.

In this post I’ll look at some of the basics of these two popular gems and some of the drawbacks I’ve encountered using them. In subsequent articles I’ll explore what it takes to build your own admin interface providing admin users on your site the controls necessary to make changes to the system to keep their users happy.

After reading the rationale for why it’s good to write your own admin interface, come back here to read the other articles in the series where we look at what it takes to create our interface:

ActiveAdmin and RailsAdmin

These two widely-used gems come with essentially the same set of features out of the box:


Let’s take a look at some of the problems I’ve found while using these tools.

Not The Rails Way

ActiveAdmin introduces its own view/controller structure that you must learn. Because of this certain things you understand from Rails aren’t clear like how to pass data between the controller and display code (hint, it’s probably not via an instance variable like in Rails).

RailsAdmin doesn’t really follow a view/controller pattern at all. Instead you define a series of view types right along with their display information.

Also, although you can define normal Rails template views to be used by each of these gems, they each come with their own display DSLs. The gems attempt to leverage meta data from the models, like model attributes and types, to display the data with less code needing to be written. There are provisions for using whatever templating system you’ve chosen for your application, like ERB or HAML, but that’s not what the admin gems use out of the box.

Soon You’re All In

By default, once you’ve set up a model to use one of these gems it will display all fields on that model. This seems good at first until you take a look at a table or particularly long display or create/update form. There may be old fields on the model or fields your admin never cares about. Fortunately, both gems allow you to override the default and configure which fields will appear in the various displays.

The downside is that once you start configuring fields for a model you must remember to add or exclude new fields from the admin configuration as you add them to your model. I find that fairly soon I am choosing which fields to display for all my models and this is no more convenient than if I were building my own admin interface.

The Admin Definition Code Ends up in Weird Places

ActiveAdmin puts its configuration/code in an apps/admin subdirectory. RailsAdmin either puts the entire configuration in one big file in config/initializers/rails_admin.rb or has you include it in each model. In either case this doesn’t follow Rails' conventions for locating controller and view code.

You May End up With Inefficient Queries

While you can configure custom derived fields for the various view types it can sometimes be difficult crafting efficient queries. This is especially true for things like associated records where you might want to do something like counting or summing some attributes of those records. It gets even worse when you want to display some aggregate values of associated models followed by a ratio of two of them that you’ve already calculated. The table display logic will cause your application to loop through queries for each aggregate value then go back and possibly do both queries yet again to calculate the ratio.

Limited View Types Per Model Class

ActiveAdmin only allows controls for a given model to be defined once. If you want an index table with a different set of information you will need to derive another model specifically for that purpose. Contrast this to what you might do in a vanilla Rails application where you could either create additional actions on a model’s controller or use one action that looks at additional URL parameters to produce different index views.

Can be Too Powerful

Because the admin gems abstract away operations like record deletion you might need to be careful that associated records are properly deleted (or not) as per your business requirements. You encounter a similar problem when creating new records, especially if you’re trying not to use ActiveRecord callbacks (which generally, you should try to avoid).

It’s nice having all the controls you might want added to the interface for you but you need to make sure that the default behaviors of your models match what you intend for the application especially when you’re not directly invoking operations like model object delete and create.

It Bloats Your Application

These admin gems drag in a bunch of other dependencies when you add them to your Gemfile. I’ve written elsewhere on why lots of gems in your application can be a problem.

Summing up

There are a lot of tradeoffs to consider when using an admin gem in your application. Over the next few weeks I’ll be examining just how hard it would be to patch together an equivalent set of functionality through smaller gems and coding your admin interface yourself. In the process we’ll see if we can’t build a more robust and powerful admin interface that better suits the needs of our admin users without having to spend too much on development in the process.

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