# Loading content later

When parts of your page become slow, e.g, a metrics table that is expensive to render:

```ruby
# /dashboard.json.props
json.header do
 ...
end

json.metrics do
  sleep 10 # expensive operation
  json.total_visitors 30
end
```

A common approach is to load content in async fashion by building out another set of routes, controllers, tests, with more work on the frontend to manage state, call fetch, etc.

With Breezy, we can turn content async with a single setting.

```ruby
json.metrics(defer: :auto) do
  sleep 10 # expensive operation
  json.total_visitors 30
end
```

With `defer: :auto`, PropsTemplate will render `order.json.props` as usual, but without `json.metrics`, then when the content is received by the client, Breezy will automatically make an `remote` request for anything that was skipped:

```javascript
remote('/dashboard?bzq=data.metrics')
```

It is up to you to handle the case when `metrics` starts out empty. For example:

```javascript
//...in your component

  render() {
    return (
      <div>
        {_.isEmpty(this.props.metrics) ? this.renderLoading() : this.renderDashboard()}
      </div>
    )
  }
```

Alternatively, you can use a placeholder like so:

```ruby
json.metrics(defer: [:auto, placeholder: {total_visitors: 0}]) do
  sleep 10 # expensive operation
  json.total_visitors 30
end
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://jho406.gitbook.io/breezy/dev/recipes/load-content-later.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.