goji

v0.9.1

Published

2 years ago

An HTML templating engine inspired by Thymeleaf

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jsumners

template templating thymeleaf html hapi hapijs

Goji

Goji is a template engine for Node.js that conforms to the Hapi view engine requirements.

Goji was inspired by Thymeleaf. The name was picked from Wikipedia's list of herbs based on whimsy and availability.

Goji's templates are (mostly) valid HTML. Goji templates rely on custom attributes that are replaced during the compilation and rendering process.

For the API documentation see -- http://jsumners.github.io/goji/Goji.html

For a short example project see -- https://github.com/jsumners/goji-hapi-example

Install

$ npm install --save goji

Example

Template

<!DOCTYPE html>
<html>
<head></head>
<body>

  <div g-text="foo.bar">This should be replaced with the value of foo.bar</div>
  <div g-text="foobar()">This should be replaced with the result of foobar()</div>
  <div g-text="answer === 41 ? foo.bar : 'nope'"></div>
  <div g-text="(answer === 42) ? foo.bar : 'nope'"></div>

</body>
</html>

Processing

var Goji = require('goji');
var goji = new Goji();
var template = goji.loadTemplateNamed('template');

var renderer = goji.compile(template);
var context = {
  foo: {
    bar: 'foo.bar'
  },
  foobar: function foobar() {
    return 'foobar() invoked';
  },
  answer: 42
};

console.log(renderer(context));

Compiler Options

Goji's compiler will load templates based on name when parsing g-include or g-replace attributes, and when using the loadTemplateNamed(name) method.

By default, the compiler will look for templates with a file extension of ".html" in an "html" directory that is in the same directory as your project's node_modules directory. Said templates will be cached for five minutes. If you need to change this behavior, you can use the Compiler Options object:

cache: Set to true (default) to enable caching of compiled templates. Set to false to compile templates every load.
cacheTTL: Time, in seconds, to keep templates in the cache. Default value is 300 (5 minutes).
templatesDir: The location where templates are stored. This should be the full path (use path.resolve). If it is not present, then it will be set to an "html" directory that is in the same directory as a node_modules directory.
partialsDir: The location where partial templates are stored. Partials are snippets of html that will be included via the g-partial attribute. The default value for this is (templatesDir + '/partials').
templatesExt: The file extension used on template files. This defaults to ".html". Note that it should include the leading dot.

{
  cache: true,
  cacheTTL: 300,
  templatesDir: '/path/to/your/templates/directory',
  partialsDir: '/path/to/your/templates/partials/directory',
  templatesExt: '.html'
}

The compiler options can be passed to the Goji constructor, or to the compile method.

Template Language

As mentioned in the introduction, Goji uses custom attributes on standard HTML elements. Thus Goji's templating "language" is really just vanilla HTML.

However, the values of those attributes are not standard. Gogi's attribute values are a mixture of a JavaScript expression language and simple identifiers.

Expression Language

Goji's expression language is a subset of vanilla JavaScript. It will evaluate simple calculations, ternary operations, object lookups, and invoke methods.

Any time an expression is evaluated it is done so within a context. The context is a regular JavaScript object literal. For example, the following literal is a completely valid context that can be used as normal within the expression:

{
  foo: {
    bar: [1, 2, 3]
  },
  foobar: function foobar() {
    return 'result of foobar()';
  },
  bar: 'bar',
  baz: 42
}

The expression language used is exprjs. To see a complete rundown of the available expressions, view their test-expr.js.

Supported Attributes

g-attr

g-attr allows you to modify any generic attribute. g-attr attribute values are an expression in the form:

value: where value is the name of an attribute to modify/add. For example: g-attr="href". This is a shortcut for a single string expression
'value': same as above, but as an actual string expression
['value', 'value', ...]: an array of attribute names to modify/add. For example: g-attr="['href', 'data-foo']"

Each named attribute in the g-attr expression will take its value from an attribute, who's value is an expression, named in the format g-attr-attributeName. For example: g-attr="data-foo" will get the value for attribute data-foo from the expression in the value of the g-attr-data-foo attribute.

Thus, the following template:

<a g-attr="['href', 'id']" g-attr-href="foo.url" g-attr-id="foo.id">foo</a>

With the context:

{
  foo: {
    url: 'http://example.com/foo',
    id: 'foobar'
  }
}

Will render to:

<a href="http://example.com/foo" id="foobar">foo</a>

Note: if you modify the class attribute with this method then it will overwrite any class names in a pre-existing class attribute. To append or prepend classes, use g-class and g-classprepend.

g-class

g-class appends the result of an expression to the element's class attribute. For example, given the following HTML:

<div g-class="foo.class" class="bar">placeholder</div>

The rendered template would be:

<div class="bar foo">placeholder</div>

Where the expression foo.class evaluates to "foo".

If the element does not already have a class attribute, the the attribute will be added.

g-classprepend

g-classprepend works like g-class except it prepends the class attribute with the result of the g-classprepend expression.

g-text

g-text substitutes the result of an expression in place of the element's content. For example, given the following HTML:

<p>Hello <span g-text="'world'">??</span>!</p>

The rendered template would be:

<p>Hello <span>world</span>!</p>

g-html

g-html works the same as g-text except it renders embedded HTML. For example, given the following HTML:

<p>Hello <span g-html="'<strong>world</strong>'">??</span>!</p>

The rendered template would be:

<p>Hello <span><strong>world</strong></span>!</p>

With the browser rendering the strong element appropriately, e.g. world. Whereas with g-text, the browser would render the text "<strong>world</strong>".

g-each

g-each is used to iterate over an array. It uses a simple expression to select the array and name the iteration variable. The expression is in the form [iteration variable name] in [array name]. For example:

<ul>
  <li g-each="item in items" g-text="item">placeholder</li>
</ul>

If the context is:

{items: ['list item 1', 'list item 2', 'list item 3']}

Then the rendered content would be:

<ul>
  <li>list item 1</li>
  <li>list item 2</li>
  <li>list item 3</li>
</ul>

However, if the template is:

<table>
  <tr g-each="row in rows">
    <td g-text="row.cell1">cell1</td>
    <td g-text="row.cell2">cell2</td>
  </tr>
</table>

And the context is:

{
  rows: [
    {cell1: 'r1c1', cell2: 'r1c2'},
    {cell1: 'r2c1', cell2: 'r2c2'}
  ]
}

Then the rendered content would be:

<table>
  <tr>
    <td>r1c1</td>
    <td>r1c2</td>
  </tr>
  <tr>
    <td>r2c1</td>
    <td>r2c2</td>
  </tr>
</table>

There are a few things to notice in these examples:

If the template element has both g-each and g-text attributes, then the template element will be used as the template for the iterations.
If the template element only has a g-each attribute, then the parent element's content will be used as the template for the iterations.
In either case 1 or 2, the content of the parent element will be replaced with the rendered content.

g-each includes the following extra context on each iteration:

{
  iter: {
    i: `number`,
    odd: `boolean`,
    even: `boolean`
  }
}

Thus, on the third iteration, the extra context would be:

{
  iter: {
    i: 2,
    odd: false,
    even: true
  }
}

Combined with g-class, you can render the following template:

<ul>
    <li g-each="item in items"
        g-text="item"
        g-class="(iter.odd) ? 'odd' : 'even'">placeholder</li>
  </ul>

Into:

<ul>
  <li class="even">list item 1</li>
  <li class="odd">list item 2</li>
  <li class="even">list item 3</li>
</ul>

Given the same context as the first example in this section.

g-if

g-if is Goji's conditional attribute. If the expression supplied in a g-if attribute value evaluates to true then the whole block will be parsed and rendered. If the expression evaluates to false, then the whole block will be removed without futher processing.

For example:

<div g-if="1 === 1">
  <p g-text="'This will be rendered'">placeholder</p>
  <p g-if="1 === 1" g-text="'As will this'">placeholder</p>
  <p g-if="1 === 2">This will not</p>
</div>

Will render to the following:

<div>
  <p>This will be rendered</p>
  <p>As will this</p>
</div>

g-include

g-include inserts the content of a fragment in place of the element's content. The value of g-include is a simple identifier in the form [templateName]::[fragmentId]. For example, given the following HTML:

<div class="container">
  <div g-include="fooTemplate::#bar">This will be replaced</div>
</div>

Goji will look for a template file named "fooTemplate", parse it, and then retrieve the content from an element with an id attribute value of "bar". So, if fooTemplate's content is:

<p id="bar">bar's content</p>

Then the rendered template will be:

<div class="container">
  <div>bar's content</div>
</div>

g-replace

g-replace works much like g-include, the difference is that g-replace replaces the element on which it is an attribute. Thus, given the same example as in g-include the rendered template would be:

<div class="container">
  <p id="bar">bar's content</p>
</div>

g-partial

g-partial is similar to g-include and g-replace. The difference is that g-partial is 1) processed during the render phase and 2) the attribute value is an expression. The result of the expression is expected to be the name of another template file. Said template is then loaded, rendered, and injected as the body of the element upon which the g-partial attribute is present.

Thus, given the following document:

<html>
<head></head>
<body>

  <main g-partial="partial.name">
    placeholder
  </main>

</body>
</html>

With a partial template named "indexBody.html" in the templates directory who's content is merely:

<p>Hello world!</p>

And a context of:

{
  partial: {
    name: 'indexBody'
  }
}

Then the rendered document would be:

<html>
<head></head>
<body>

  <main>
    <p>Hello world!</p>
  </main>

</body>
</html>

Note: as of Goji version 0.8.0 the default path for partials is in a sub-directory of the main templates directory. The default name for this sub-directory is partials.

License

http://jsumners.mit-license.org

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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Readme

Goji

Install

Example

Template

Processing

Compiler Options

Template Language

Expression Language

Supported Attributes

g-attr

g-class

g-classprepend

g-text

g-html

g-each

g-if

g-include

g-replace

g-partial

License