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Introduction

vision decorates the server, request, and h response toolkit interfaces with additional methods for managing view engines that can be used to render templated responses.

vision also provides a built-in handler implementation for creating templated responses.

Most interaction with vision is done via the h response toolkit and server interfaces.

Example

const Hapi = require('@hapi/hapi');
const Vision = require('@hapi/vision');

const server = Hapi.Server({ port: 3000 });

const provision = async () => {

    await server.register(Vision);
    await server.start();

    console.log('Server running at:', server.info.uri);
};

provision();

The examples in the examples folder can be run with node.

git clone https://github.com/hapijs/vision.git && cd vision
npm install

node examples/handlebars

☝️ That command will run the handlebars basic template. There are three more examples in there: for helpers, layout, and partials.

Use this hierarchy to know which commands to run, e.g.

node examples/mustache
node examples/mustache/partials
node examples/jsx

- cms // A bare-bones Content Management System with a WYSIWYG editor
- ejs
  - layout
- handlebars
  - helpers
  - layout
  - partials
- jsx // React server-side rendering with `hapi-react-views`
- marko
- mixed // Using multiple render engines (handlebars and pug)
- mustache
  - layout
  - partials
- nunjucks
- pug
- twig

vision is compatible with most major templating engines out of the box. Engines that don't follow the normal API pattern can still be used by mapping their API to the vision API. Some of the examples below use the compile and prepare methods which are part of the API.

EJS

const Ejs = require('ejs');
const Hapi = require('@hapi/hapi');
const Vision = require('@hapi/vision');

const server = Hapi.Server({ port: 3000 });

const rootHandler = (request, h) => {

    return h.view('index', {
        title: 'examples/ejs/templates/basic | Hapi ' + request.server.version,
        message: 'Hello Ejs!'
    });
};

const provision = async () => {

    await server.register(Vision);

    server.views({
        engines: { ejs: Ejs },
        relativeTo: __dirname,
        path: 'examples/ejs/templates/basic'
    });

    server.route({ method: 'GET', path: '/', handler: rootHandler });

    await server.start();
    console.log('Server running at:', server.info.uri);
};

provision();

Handlebars

const Handlebars = require('handlebars');
const Hapi = require('@hapi/hapi');
const Vision = require('@hapi/vision');

const server = Hapi.Server({ port: 3000 });

const rootHandler = (request, h) => {

    return h.view('index', {
        title: 'examples/handlebars/templates/basic | hapi ' + request.server.version,
        message: 'Hello Handlebars!'
    });
};

const provision = async () => {

    await server.register(Vision);

    server.views({
        engines: { html: Handlebars },
        relativeTo: __dirname,
        path: 'examples/handlebars/templates/basic'
    });

    server.route({ method: 'GET', path: '/', handler: rootHandler });

    await server.start();
    console.log('Server running at:', server.info.uri);
};

provision();

Pug

const Path = require('path');

const Hapi = require('@hapi/hapi');
const Pug = require('pug');
const Vision = require('@hapi/vision');

const server = Hapi.Server({ port: 3000 });

const rootHandler = (request, h) => {

    return h.view('index', {
        title: 'examples/pug/templates | Hapi ' + request.server.version,
        message: 'Hello Pug!'
    });
};

const provision = async () => {

    await server.register(Vision);

    server.views({
        engines: { pug: Pug },
        relativeTo: __dirname,
        path: 'examples/pug/templates',
        compileOptions: {
            // By default Pug uses relative paths (e.g. ../root.pug), when using absolute paths (e.g. include /root.pug), basedir is prepended.
            // https://pugjs.org/language/includes.html
            basedir: Path.join(__dirname, 'examples/pug/templates')
        }
    });

    server.route({ method: 'GET', path: '/', handler: rootHandler });

    await server.start();
    console.log('Server running at:', server.info.uri);
};

provision();

Marko

const Hapi = require('@hapi/hapi');
const Marko = require('marko');
const Vision = require('@hapi/vision');

const server = Hapi.Server({ port: 3000 });

const rootHandler = (request, h) => {

    return h.view('index', {
        title: 'examples/marko/templates | Hapi ' + request.server.version,
        message: 'Hello Marko!'
    });
};

const provision = async () => {

    await server.register(Vision);

    server.views({
        engines: {
            marko: {
                compile: (src, options) => {

                    const opts = { preserveWhitespace: true, writeToDisk: false };

                    const template = Marko.load(options.filename, opts);

                    return (context) => {

                        return template.renderToString(context);
                    };
                }
            }
        },
        relativeTo: __dirname,
        path: 'examples/marko/templates'
    });

    server.route({ method: 'GET', path: '/', handler: rootHandler });

    await server.start();
    console.log('Server running at:', server.info.uri);
};

provision();

Mustache

const Hapi = require('@hapi/hapi');
const Mustache = require('mustache');
const Vision = require('@hapi/vision');

const server = Hapi.Server({ port: 3000 });

const rootHandler = (request, h) => {

    return h.view('index', {
        title: 'examples/mustache/templates/basic | Hapi ' + request.server.version,
        message: 'Hello Mustache!'
    });
};

const provision = async () => {

    await server.register(Vision);

    server.views({
        engines: {
            html: {
                compile: (template) => {

                    Mustache.parse(template);

                    return (context) => {

                        return Mustache.render(template, context);
                    };
                }
            }
        },
        relativeTo: __dirname,
        path: 'examples/mustache/templates/basic'
    });

    server.route({ method: 'GET', path: '/', handler: rootHandler });

    await server.start();
    console.log('Server running at:', server.info.uri);
};

provision();

Nunjucks

const Hapi = require('@hapi/hapi');
const Nunjucks = require('nunjucks');
const Vision = require('@hapi/vision');

const server = Hapi.Server({ port: 3000 });

const rootHandler = (request, h) => {

    return h.view('index', {
        title: 'examples/nunjucks/templates | Hapi ' + request.server.version,
        message: 'Hello Nunjucks!'
    });
};

const provision = async () => {

    await server.register(Vision);

    server.views({
        engines: {
            html: {
                compile: (src, options) => {

                    const template = Nunjucks.compile(src, options.environment);

                    return (context) => {

                        return template.render(context);
                    };
                },

                prepare: (options, next) => {

                    options.compileOptions.environment = Nunjucks.configure(options.path, { watch : false });

                    return next();
                }
            }
        },
        relativeTo: __dirname,
        path: 'examples/nunjucks/templates'
    });

    server.route({ method: 'GET', path: '/', handler: rootHandler });

    await server.start();
    console.log('Server running at:', server.info.uri);
};

provision();

Twig

const Hapi = require('@hapi/hapi');
const Twig = require('twig');
const Vision = require('@hapi/vision');

const server = Hapi.Server({ port: 3000 });

const rootHandler = (request, h) => {

    return h.view('index', {
        title: 'examples/twig/templates | Hapi ' + request.server.version,
        message: 'Hello Twig!'
    });
};

const provision = async () => {

    await server.register(Vision);

    server.views({
        engines: {
            twig: {
                compile: (src, options) => {

                    const template = Twig.twig({ id: options.filename, data: src });

                    return (context) => {

                        return template.render(context);
                    };
                }
            }
        },
        relativeTo: __dirname,
        path: 'examples/twig/templates'
    });

    server.route({ method: 'GET', path: '/', handler: rootHandler });

    await server.start();
    console.log('Server running at:', server.info.uri);
};

provision();

Eta

const Hapi = require('@hapi/hapi');
const Eta = require('eta');
const Vision = require('@hapi/vision');

const server = Hapi.Server({ port: 3000 });

const rootHandler = (request, h) => {

    return h.view('index', {
        title: 'examples/eta/templates | Hapi ' + request.server.version,
        message: 'Hello Eta!'
    });
};

const provision = async () => {

    await server.register(Vision);

    server.views({
        engines: {
            eta: {
                compile: (src, options) => {

                    const compiled = Eta.compile(src, options);

                    return (context) => {

                        return Eta.render(compiled, context);
                    };
                }
            }
        },
        /**
         * This is the config object that gets passed to the compile function
         * defined above. This should contain the eta configuration object
         * described at https://eta.js.org/docs/api/configuration Only some of
         * the configuration are relevant when using with hapijs.
         */
        compileOptions: {
            autoEscape: true,
            tags: ['{{', '}}']
        },
        relativeTo: __dirname,
        path: 'examples/eta/templates'
    });

    server.route({ method: 'GET', path: '/', handler: rootHandler });

    await server.start();
    console.log('Server running at:', server.info.uri);
};

provision();

Registration

Vision can be registered multiple times and receives views manager options as registration options.

Example:

internals.provision = async () => {

    await server.register({
        plugin: require('@hapi/vision'),
        options: {
            engines: { html: require('handlebars') },
            path: __dirname + '/templates'
        }
    })

    const context = {
        title: 'Registration Example',
        message: 'Hello, World'
    };

    return server.render('hello', context);
};

internals.provision();

Views Manager

The Views Manager is configured with registration options or by calling server.views(options)

options

  • engines - required object where each key is a file extension (e.g. 'html', 'hbr'), mapped to the npm module used for rendering the templates. Alternatively, the extension can be mapped to an object with the following options:

    • module - the npm module used for rendering the templates. The module object must contain the compile() function:
      • compile() - the rendering function. The required function signature depends on the compileMode settings (see below). If compileMode is 'sync', the signature is compile(template, options), the return value is a function with signature function(context, options) (the compiled sync template), and the method is allowed to throw errors. If compileMode is 'async', the signature is compile(template, options, next) where next has the signature function(err, compiled), compiled is a function with signature function(context, options, callback) (the compiled async template) and callback has the signature function(err, rendered).
      • prepare(config, next) - initializes additional engine state. The config object is the engine configuration object allowing updates to be made. This is useful for engines like Nunjucks that rely on additional state for rendering. next has the signature function(err).
      • registerPartial(name, src) - registers a partial for use during template rendering. The name is the partial path that templates should use to reference the partial and src is the uncompiled template string for the partial.
      • registerHelper(name, helper) - registers a helper for use during template rendering. The name is the name that templates should use to reference the helper and helper is the function that will be invoked when the helper is called.
    • any of the views options listed below (except defaultExtension) to override the defaults for a specific engine.

  • compileMode - specify whether the engine compile() method is 'sync' or 'async'. Defaults to 'sync'.

  • defaultExtension - defines the default filename extension to append to template names when multiple engines are configured and not explicit extension is provided for a given template. No default value.

  • path - the root file path, or array of file paths, used to resolve and load the templates identified when calling h.view(). Defaults to current working directory.

  • partialsPath - the root file path, or array of file paths, where partials are located. Partials are small segments of template code that can be nested and reused throughout other templates. Defaults to no partials support (empty path).

  • helpersPath - the directory path, or array of directory paths, where helpers are located. Helpers are functions used within templates to perform transformations and other data manipulations using the template context or other inputs. Each valid template file in the helpers directory is loaded and the file name is used as the helper name. The files must export a single method with the signature function(context) and return a string. Sub-folders are not supported and are ignored. Defaults to no helpers support (empty path). Note that pug does not support loading helpers this way.

  • relativeTo - a base path used as prefix for path and partialsPath. No default.

  • layout - if set to true or a layout filename, layout support is enabled. A layout is a single template file used as the parent template for other view templates in the same engine. If true, the layout template name must be 'layout.ext' where 'ext' is the engine's extension. Otherwise, the provided filename is suffixed with the engine's extension and loaded. Disable layout when using Jade as it will handle including any layout files independently. Defaults to false.

  • layoutPath - the root file path, or array of file paths, where layout templates are located (using the relativeTo prefix if present). Defaults to path.

  • layoutKeyword - the key used by the template engine to denote where primary template content should go. Defaults to 'content'.

  • encoding - the text encoding used by the templates when reading the files and outputting the result. Defaults to 'utf8'.

  • isCached - if set to false, templates will not be cached (thus will be read from file on every use). Defaults to true.

  • allowAbsolutePaths - if set to true, allows absolute template paths passed to h.view(). Defaults to false.

  • allowInsecureAccess - if set to true, allows template paths passed to h.view() to contain '../'. Defaults to false.

  • compileOptions - options object passed to the engine's compile function. Defaults to empty options {}.

  • runtimeOptions - options object passed to the returned function from the compile operation. Defaults to empty options {}.

  • contentType - the content type of the engine results. Defaults to 'text/html'.

  • context - a global context used with all templates. The global context option can be either an object or a function (can be async or return a promise) that takes the request as its only argument and returns a context object. The request object is only provided when using the view handler or h.view(). When using server.render() or request.render(), the request argument will be null. When rendering views, the global context will be merged with any context object specified on the handler or using h.view(). When multiple context objects are used, values from the global context always have lowest precedence.

manager.registerHelper(name, helper)

Registers a helper, on all configured engines that have a registerHelper() method, for use during template rendering. Engines without a registerHelper() method will be skipped. The name is the name that templates should use to reference the helper and helper is the function that will be invoked when the helper is called.

manager.render(template, context, options, [callback])

Renders a template. This is typically not needed and it is usually more convenient to use server.render().

manager.getEngine(ext)

  • ext- The extension used when registering the engine -- check the keys used when configuring engines in views manager options

manager.clearCache(template, [engine])

  • template - the template filename and path, relative to the views manager templates path (path or relativeTo).
  • engine - the engine returned by manager.getEngine(ext)

Server

server.views(options)

  • Initializes a plugin's view manager by receiving manager options
  • Returns the newly created view manager for the plugin that called it.

server.render(template, context, [options], [callback])

Uses the server views manager to render a template where:

  • template - the template filename and path, relative to the views manager templates path (path or relativeTo).
  • context - optional object used by the template to render context-specific result. Defaults to no context ({}).
  • options - optional object used to override the views manager configuration.
  • callback - the callback function with signature function (err, rendered, config) where:
    • err - the rendering error if any.
    • rendered - the result view string.
    • config - the configuration used to render the template.

If no callback is provided, a Promise object is returned. The returned promise is resolved with only the rendered content and not the configuration object.

const Hapi = require('@hapi/hapi');
const server = Hapi.Server({ port: 3000 });

const internals = {};

internals.provision = async () => {

    await server.register(require('@hapi/vision'));

    server.views({
        engines: { html: require('handlebars') },
        path: __dirname + '/templates'
    });

    const context = {
        title: 'Views Example',
        message: 'Hello, World'
    };

    return server.render('hello', context);
};

internals.provision();

server.getViewsManager()

Returns the closest Views manager to your realm (either on your realm or inherited from an ancestor realm)

Requests

request.render(template, context, [options], [callback])

request.render() works the same way as server.render() but is for use inside of request handlers. server.render() does not work inside request handlers when called via request.server.render() if the view manager was created by a plugin. This is because the request.server object does not have access to the plugin realm where the view manager was configured. request.render() gets its realm from the route that the request was bound to.

Note that this will not work in onRequest extensions added by the plugin because the route isn't yet set at this point in the request lifecycle and the request.render() method will produce the same limited results server.render() can. When using the onRequest extension, use the h response toolkit interface instead.

const Hapi = require('@hapi/hapi');
const server = Hapi.Server({ port: 3000 });

const internals = {};

internals.provision = async () => {

    await server.register(require('@hapi/vision'));

    server.views({
        engines: { html: require('handlebars') },
        path: __dirname + '/templates'
    });

    server.route({
        method: 'GET',
        path: '/view',
        handler: function (request, h) {

            return request.render('test', { message: 'hello' });
        }
    });
};

internals.provision();

request.getViewsManager()

Returns the closest Views manager to your realm (either on your realm or inherited from an ancestor realm)

The view handler

The view handler can be used with routes registered in the same realm as the view manager. The handler takes an options parameter that can be either a string or an object. When the options parameter is a string, it should be the filename and path of the template relative to the templates path configured via the views manager. When the options parameter is an object, it may have the following keys:

  • template - the template filename and path, relative to the templates path configured via the server views manager.
  • context - optional object used by the template to render context-specific result. Defaults to no context {}.
  • options - optional object used to override the server's views manager configuration for this response. Cannot override isCached, partialsPath, or helpersPath which are only loaded at initialization.

The rendering context contains the params, payload, query, and pre values from the request by default (these can be overriden by values explicitly set via the options).

const Hapi = require('@hapi/hapi');
const server = Hapi.Server({ port: 3000 });

const internals = {};

internals.provision = async () => {

    await server.register(require('@hapi/vision'));

    server.views({
        engines: { html: require('handlebars') },
        path: __dirname + '/templates'
    });

    server.route({
        method: 'GET',
        path: '/',
        handler: {
            view: {
                template: 'hello',
                context: {
                    title: 'Views Example',
                    message: 'Hello, World'
                }
            }
        }
    });
};

internals.provision();

Response Toolkit Interface

h.view(template, [context, [options]])

Uses the response toolkit interface by means of returning control over to the router with a templatized view response where:

  • template - the template filename and path, relative to the templates path configured via the server views manager.
  • context - optional object used by the template to render context-specific result. Defaults to no context {}.
  • options - optional object used to override the server's views manager configuration for this response. Cannot override isCached, partialsPath, or helpersPath which are only loaded at initialization.

Returns a response object. The generated response will have the variety property set to view.

The same lifecycle workflow applies.

const Hapi = require('@hapi/hapi');
const server = Hapi.Server({ port: 3000 });

const internals = {};

internals.provision = async () => {

    await server.register(require('@hapi/vision'));

    server.views({
        engines: { html: require('handlebars') },
        path: __dirname + '/templates'
    });

    const rootHandler = function (request, h) {

        const context = {
            title: 'Views Example',
            message: 'Hello, World'
        };

        return h.view('hello', context);
    };

    server.route({ method: 'GET', path: '/', handler: rootHandler });
};

internals.provision();

h.getViewsManager()

Returns the closest Views manager to your realm (either on your realm or inherited from an ancestor realm)

Ex template used in these docs

templates/hello.html

<html>
    <head>
        <title>{{title}}</title>
    </head>
    <body>
        <div>
            <h1>{{message}}</h1>
        </div>
    </body>
</html>

Typescript

If you'd like to type out the way Vision is used, you can do so with the following interfaces:

declare module '@hapi/vision' {

    // User defined
    type CustomTemplates = (
        'test' | 'hello' | 'temp1'
    );

    // User defined
    type CustomLayout = (
        'auth' | 'unauth' | 'admin'
    )

    interface ViewTypes {
        template: CustomTemplates
        layout: CustomLayout
    }
}

You should now get typings on your response handler (only), and anywhere where layouts is an option

const route = {
    ...
    handler: {
        view: {
            template: 'test', // should autocomplete
            options: { layout: 'auth' } // should autocomplete
        }
    }
}

If you'd like to also type check the decorated handlers, you can augment the following interfaces:

declare module '@hapi/vision' {

    // User defined
    type CustomTemplates = (
        'test' | 'hello' | 'temp1'
    );

    // User defined
    type CustomLayout = (
        'auth' | 'unauth' | 'admin'
    )

    // server.render(...)
    interface RenderMethod {
        (template: CustomTemplates, context?: string): Promise<string>
    }

    // { handler: (req) => req.render(...) }
    interface RequestRenderMethod {
        (template: CustomTemplates, context?: string): Promise<string>
    }

    // { handler: (req, h) => h.view(...) }
    interface ToolkitRenderMethod {
        (template: CustomTemplates, context?: string): ResponseObject
    }

}

This is useful for when you may want to make strict checks against template / context combinations:

    // { handler: (req, h) => h.view(...) }
    interface ToolkitRenderMethod {
        (template: 'test', context: { apples: 5 }): ResponseObject
        (template: 'hello', context: { oranges: true }): ResponseObject
        (template: 'temp1', context: { bananas: 'green' }): ResponseObject
    }