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Filters

Filters are used to format the rendered contents.

Example:

message: <%= "foo\nbar" | dbg %>

message: &quot;foo\nbar&quot;

Note

Since dbg filter accepts <T: std::fmt::Debug> types, that type isn't required to implement Render trait. That means you can pass the type which doesn't implement Render trait.

Syntax

  • Apply filter and HTML escaping
<%= expression | filter %>
  • Apply filter only
<%- expression | filter %>

Built-In Filters

Built-In filters can be found in sailfish::runtime::filter module.

JSON

The json filter requires the json feature and a value implementing serde::Serialize. Use <%- value | json %> to produce JSON:

{"data": <%- data | json %>}

This form replaces <, >, &, ', U+2028, and U+2029 with JSON Unicode escapes. For example, "</script>" becomes "\u003c/script\u003e". The serialized text changes, but parsing the JSON recovers the original data.

It can also be embedded directly as a JavaScript value:

<script>
  const data = <%- data | json %>;
</script>

Do not add quotes around the expression: the filter already serializes strings with their quotes. The same escaping also supports a JSON data block:

<script id="page-data" type="application/json"><%- data | json %></script>

Read the data block with JSON.parse(document.getElementById("page-data").textContent). For a double-quoted HTML attribute, use HTML escaping instead:

<div data-value="<%= data | json %>"></div>

These examples do not make raw JSON suitable for event handler attributes or interpolation inside an existing JavaScript string. Serialization writes directly to the output buffer; if it fails, discard the partial rendering.

Useful Filters

You can also use the Display filter to do things like format a date, or a UUID.

  • Easily Display A Date
<span><%= chrono::NaiveDate::from_ymd_opt(2015, 9, 5).unwrap().and_hms_opt(23, 56, 4).unwrap().format("around %l %p on %b %-d") | disp %></span>

<span>around 11 PM on Sep 5</span>
  • Easily Display A UUID
<span><%= uuid::Uuid::new_v4().urn() | disp %></span>

<span>urn:uuid:c3602585-a9a1-43f5-b0e6-8bc05d5444dd</span>