mirror of https://github.com/hashicorp/consul
62 lines
2.9 KiB
Markdown
62 lines
2.9 KiB
Markdown
## DataSource
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```handlebars
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<DataSource
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@src="/dc/nspace/services"
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@loading="eager"
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@onchange={{action (mut items) value="data"}}
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@onerror={{action (mut error) value="error"}}
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/>
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```
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### Arguments
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| Argument | Type | Default | Description |
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| --- | --- | --- | --- |
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| `src` | `String` | | The source to subscribe to updates to, this should map to a string based URI |
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| `loading` | `String` | eager | Allows the browser to defer loading offscreen DataSources (`eager\|lazy`). Setting to `lazy` only loads the data when the DataSource is visible in the DOM (inc. `display: none\|block;`) |
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| `onchange` | `Function` | | The action to fire when the data changes. Emits an Event-like object with a `data` property containing the data. |
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| `onerror` | `Function` | | The action to fire when an error occurs. Emits ErrorEvent object with an `error` property containing the Error. |
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The component takes a `src` or an identifier (a uri) for some data and then emits `onchange` events whenever that data changes. If an error occurs whilst listening for data changes, an `onerror` event is emitted.
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Setting `@loading="lazy"` uses `IntersectionObserver` to activate/deactive event emitting until the `<DataSource />` element is displayed in the DOM. This means you can use CSS `display: none|block;` to control the loading and stopping loading of data for usage with CSS based tabs and such-like.
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Consuls HTTP API DataSources use Consul's blocking query support for live updating of data.
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Behind the scenes in the Consul UI we map URIs back to our `ember-data` backed `Repositories` meaning we can essentially redesign the URIs used for our data to more closely fit our needs. For example we currently require that **all** HTTP API URIs begin with `/dc/nspace/` values whether they require them or not.
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`DataSource` is not just restricted to HTTP API data, and can be configured to listen for data changes using a variety of methods and sources. For example we have also configured `DataSource` to listen to `LocalStorage` changes using the `settings://` pseudo-protocol in the URI (See examples below).
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### Example
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Straightforward usage can use `mut` to easily update data within a template
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```handlebars
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{{! listen for HTTP API changes}}
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<DataSource @src="/dc/nspace/services"
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@onchange={{action (mut items) value="data"}}
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@onerror={{action (mut error) value="error"}}
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/>
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{{! the value of items will change whenever the data changes}}
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{{#each items as |item|}}
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{{item.Name}} {{! < Prints the item name }}
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{{/each}}
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{{! listen for Settings (local storage) changes}}
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<DataSource @src="settings://consul:token"
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@onchange={{action (mut token) value="data"}}
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@onerror={{action (mut error) value="error"}}
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/>
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{{! the value of token will change whenever the data changes}}
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{{token.AccessorID}} {{! < Prints the token AccessorID }}
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```
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### See
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- [Component Source Code](./index.js)
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- [Template Source Code](./index.hbs)
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---
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