Rails: How to reference images in CSS within Rails 4

Question

There's a strange issue with Rails 4 on Heroku. When images are compiled they have hashes added to them, yet the reference to those files from within CSS don't have the proper name adjusted. Here's what I mean. I have a file called logo.png. Yet when it shows up on heroku it is viewed as: ``` /assets/logo-200a00a193ed5e297bb09ddd96afb953.png ``` However the CSS still states: ``` background-image:url("./logo.png"); ``` The result: the image doesn't display. Anybody run into this? How can this be resolved?

Accepted Answer

Sprockets together with Sass has some nifty helpers you can use to get the job done. Sprockets will only process these helpers if your stylesheet file extensions are either `.css.scss` or `.css.sass`.

Image specific helper:

```
background-image: image-url("logo.png")
```

Agnostic helper:

```
background-image: asset-url("logo.png", image)
background-image: asset-url($asset, $asset-type)
```

Or if you want to embed the image data in the css file:

```
background-image: asset-data-url("logo.png")
```

Rails: How to reference images in CSS within Rails 4

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