BoxLang Templating Language

Overview

BoxLang's templating language uses .bxm files (BoxLang Markup) to mix HTML with dynamic server-side code. The default mode in .bxm files is HTML output — you embed BoxLang logic using <bx:*> tags and output expressions with #expression#.

---

File Types Recap

Extension	Default mode	Primary use
.bx	Script	Classes, services, models
.bxs	Script	Standalone scripts, CLI tools
.bxm	Tag/markup	Templates, views, HTML pages

---

Output Expression Syntax

Use #expression# to interpolate values. The expression is evaluated and output is HTML-escaped automatically inside <bx:output>:

<bx:output>
    <h1>Hello, #user.name#!</h1>
    <p>Today is #dateFormat( now(), "long" )#</p>
    <p>Items: #order.items.len()#</p>
</bx:output>

Always wrap output in <bx:output> — without it, #variable# is treated as a literal string and not evaluated:

<!-- BAD: #name# is printed as literal text, not evaluated -->
<p>#name#</p>

<!-- GOOD: #name# is evaluated and output -->
<bx:output><p>#name#</p></bx:output>

---

Core Template Components

<bx:output> — Render Dynamic Content

<bx:output>
    <p>User: #user.firstName# #user.lastName#</p>
    <p>Email: #encodeForHTML( user.email )#</p>
</bx:output>

Options:

• encodeFor="html" — auto-encode all expressions (recommended for untrusted data)

<!-- Auto-encode all output in this block -->
<bx:output encodeFor="html">
    <p>#userSuppliedContent#</p>
</bx:output>

<bx:set> — Declare Variables

<bx:set var="greeting" value="Hello, #user.name#!">
<bx:set var="items" value="#productService.getFeatured()#">
<bx:set var="count" value="#items.len()#">

<bx:if> / <bx:elseif> / <bx:else> — Conditionals

<bx:if condition="#user.isLoggedIn#">
    <p>Welcome back, #encodeForHTML( user.name )#!</p>
<bx:elseif condition="#session.hasGuideToken#">
    <p>Continue as guest</p>
<bx:else>
    <a href="/login">Please log in</a>
</bx:if>

<bx:loop> — Iteration

Array loop:

<bx:loop array="#products#" item="product">
    <div class="product">
        <h3><bx:output>#encodeForHTML( product.name )#</bx:output></h3>
        <p><bx:output>$#numberFormat( product.price, "0.00" )#</bx:output></p>
    </div>
</bx:loop>

Struct loop:

<bx:loop struct="#config#" item="value" key="key">
    <bx:output><p>#key#: #value#</p></bx:output>
</bx:loop>

Query loop:

<bx:loop query="#users#">
    <bx:output>
        <tr>
            <td>#users.id#</td>
            <td>#encodeForHTML( users.name )#</td>
            <td>#encodeForHTML( users.email )#</td>
        </tr>
    </bx:output>
</bx:loop>

Index / count loop:

<bx:loop from="1" to="#items.len()#" index="i">
    <bx:output><li>#i#. #items[ i ].name#</li></bx:output>
</bx:loop>

<bx:include> — Include Partial Templates

<!-- Reuse header and footer partials -->
<bx:include template="/includes/header.bxm">

<main>
    <!-- page content -->
</main>

<bx:include template="/includes/footer.bxm">

Pass variables to the included template via the current scope (variables are inherited by default in includes).

<bx:script> — Inline Script Blocks

Switch to script mode within a template:

<bx:script>
    var products  = productService.getFeatured( limit=6 )
    var totalPages = ceiling( products.recordCount / 10 )
</bx:script>

<bx:loop array="#products#" item="p">
    <bx:output><div>#p.name#</div></bx:output>
</bx:loop>

<bx:switch> / <bx:case> — Switch Statements

<bx:switch expression="#user.role#">
    <bx:case value="admin">
        <bx:include template="/views/admin-dashboard.bxm">
    </bx:case>
    <bx:case value="editor">
        <bx:include template="/views/editor-dashboard.bxm">
    </bx:case>
    <bx:defaultcase>
        <bx:include template="/views/user-dashboard.bxm">
    </bx:defaultcase>
</bx:switch>

<bx:try> / <bx:catch> — Error Handling in Templates

<bx:try>
    <bx:set var="data" value="#remoteService.getData()#">
    <bx:output><p>#data.message#</p></bx:output>
<bx:catch type="any" variable="e">
    <p class="error">Could not load data: <bx:output>#encodeForHTML( e.message )#</bx:output></p>
</bx:catch>
</bx:try>

---

Mixing Script and Tag Syntax

You can freely mix script blocks and tag components in .bxm files:

<bx:script>
    // Load data using script syntax
    var pageTitle    = "Product Catalog"
    var categories   = categoryService.getAll()
    var featuredIds  = url.keyExists( "cat" ) ? [ url.cat ] : []
</bx:script>

<!DOCTYPE html>
<html lang="en">
<head>
    <bx:output><title>#encodeForHTML( pageTitle )#</title></bx:output>
</head>
<body>
    <nav>
        <bx:loop array="#categories#" item="cat">
            <bx:output>
                <a href="/catalog?cat=#encodeForURL( cat.slug )#"
                   class="#featuredIds.contains( cat.id ) ? 'active' : ''#">
                    #encodeForHTML( cat.name )#
                </a>
            </bx:output>
        </bx:loop>
    </nav>
</body>
</html>

---

Layout / View Patterns

Nested Includes (Layout Pattern)

<!-- views/layout.bxm -->
<!DOCTYPE html>
<html lang="en">
<head>
    <bx:output><title>#pageTitle ?: "My App"#</title></bx:output>
    <link rel="stylesheet" href="/css/app.css">
</head>
<body>
    <bx:include template="/views/partials/nav.bxm">
    <main>
        <bx:include template="#contentTemplate#">
    </main>
    <bx:include template="/views/partials/footer.bxm">
</body>
</html>

<!-- In a page handler/template -->
<bx:set var="pageTitle" value="Dashboard">
<bx:set var="contentTemplate" value="/views/dashboard-content.bxm">
<bx:include template="/views/layout.bxm">

---

HTML Output Encoding Reference

Always encode user-supplied data before rendering:

<bx:output>
    <!-- HTML context — encode entities -->
    <p>#encodeForHTML( userBio )#</p>

    <!-- Attribute context -->
    <input value="#encodeForHTMLAttribute( formValue )#">

    <!-- URL context -->
    <a href="/profile?u=#encodeForURL( username )#">View Profile</a>

    <!-- JavaScript context -->
    <script>
        const name = "#encodeForJavaScript( displayName )#";
    </script>
</bx:output>

---

Query of Queries in Templates

Use <bx:query> for database queries directly in templates (acceptable for simple templates; prefer service layer for complex logic):

<bx:script>
    var users = queryExecute(
        "SELECT id, name, email FROM users WHERE active = :active ORDER BY name",
        { active: { value: true, cfsqltype: "cf_sql_bit" } }
    )
</bx:script>

<table>
    <thead><tr><th>Name</th><th>Email</th></tr></thead>
    <tbody>
        <bx:loop query="#users#">
            <bx:output>
                <tr>
                    <td>#encodeForHTML( users.name )#</td>
                    <td>#encodeForHTML( users.email )#</td>
                </tr>
            </bx:output>
        </bx:loop>
    </tbody>
</table>

---

Common Mistakes to Avoid

Mistake	Fix
#var# outside <bx:output>	Wrap in <bx:output>
Raw user data in output	Use encodeForHTML() or encodeFor="html"
Logic-heavy templates	Move to service layer; keep templates presentational
Missing closing tags	<bx:if> requires </bx:if>, <bx:loop> requires </bx:loop>
Unscoped variables	Declare with <bx:set> or <bx:script> var statements
Including with absolute OS paths	Use web-root-relative paths: /views/...