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Merge pull request #13326 from schneems/schneems/add-asset-flag

Flag `config.assets.raise_runtime_errors` in dev
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commit d6ac7d72c5c6e5a7fe4eed3566604a4b54c15bde 2 parents 6de454f + 2ff2f1b
@guilleiguaran guilleiguaran authored
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27 guides/source/asset_pipeline.md
@@ -577,6 +577,33 @@ would generate this HTML:
The `body` param is required by Sprockets.
+### Runtime Error Checking
+
+By default the asset pipeline will check for potential errors in development mode during
+runtime. To disable this behavior you can set:
+
+```ruby
+config.assets.raise_runtime_errors = false
+```
+
+When `raise_runtime_errors` is set to `false` sprockets will not check that dependencies of assets are declared properly. Here is a scenario where you must tell the asset pipeline about a dependency:
+
+If you have `application.css.erb` that references `logo.png` like this:
+
+```css
+#logo { background: url(<%= asset_data_uri 'logo.png' %>) }
+```
+
+Then you must declare that `logo.png` is a dependency of `application.css.erb`, so when the image gets re-compiled, the css file does as well. You can do this using the `//= depend_on_asset` declaration:
+
+```css
+//= depend_on_asset "logo.png"
+#logo { background: url(<%= asset_data_uri 'logo.png' %>) }
+```
+
+Without this declaration you may experience strange behavior when pushing to production that is difficult to debug. When you have `raise_runtime_errors` set to `true`, dependencies will be checked at runtime so you can ensure that all dependencies are met.
+
+
### Turning Debugging Off
You can turn off debug mode by updating `config/environments/development.rb` to
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5 railties/lib/rails/generators/rails/app/templates/config/environments/development.rb.tt
@@ -29,5 +29,10 @@ Rails.application.configure do
# This option may cause significant delays in view rendering with a large
# number of complex assets.
config.assets.debug = true
+
+ # Adds additional error checking when serving assets at runtime.
+ # Checks for improperly declared sprockets dependencies.
+ # Raises helpful error messages.
+ config.assets.raise_runtime_errors = true
<%- end -%>
end
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