Respond-to

Respond-to is an asynchronous module for Node.js that aims to replicate RoR's respond_to method. It comes with a XML formatter, it uses the built-in JSON serializer and depends on the official msgpack module.

Download

The source is available for download from GitHub. Alternatively, you can install using Node Package Manager (npm):

npm install respond-to

How to use

The easiest way to use respond-to is by calling the respondTo-function:

var respondTo = require('respond-to');
respondTo('xml', {
	users: [
		{
			id: 1,
			username: "Timvanelsloo"
		}
	]
}, function(err, data) {
	console.log(err, data);
});

This is short for:

respondTo.xml({
   ...
}, function(err, data) {});

Currently supported formats are: xml, json and msg (msgpack).

Serializing

Serializing by default is done by pulling all keys and values from an object. You can override this behaviour by implementing an as-function with the following prototype:

Something.prototype.as = function(format, options, callback) {
	
};

The format variable contains any of the supported formats (as a string). options contains a hash derived from the original options hash that was used when calling respondTo.*. It also contains a function include(key). You can call that method in order to determine what keys should be returned and what not. When you're done, you can call callback(err, result). The result can be any type of a serializable javascript object, and (when available) as gets called for that object as well.

Filtering

You can either filter by including, or by excluding certain keys. You should not both include and exclude keys at the same time.

A great feature in filtering is the ability to filter multidimensional keys.

For example, when you define an object like this:

{
    users: [
        {
            id: 1,
            name: {
                first: "Tim",
                last: "van Elsloo"
        	}
        }
    ]
}

And filter it with these keys:

{
	include: ['users.id', 'users.name.first']
}

On a sidenote, these options can be inverted into:

{
	exclude: ['users.name.last']
}

This results in:

{
	users: [
		{
			id: 1,
			name: {
				first: "Tim"
			}
		}
	]
}

You also can prototype users.name to override as(format, options, callback) with the following function:

name.as = function(format, options, callback) {
	if (options.include('first') && !options.include('last'))
		return callback(null, this.first);
	return {first: this.first, last: this.last};
};

This replaces the name-hash with only the first-value:

name: "Tim"

Please note that when you're only including certain keys, multi-dimensional keys are flattened:

['users.name.first'] == ['users', 'users.name', 'users.name.first']

Recommended: using it with Express 3.x

When you're using Express, you can also call respondTo with your response as the first parameter:

exports.index = function(req, res) {
    respondTo(res, {
        users: [
			{
				id: 1,
				username: "Timvanelsloo"
			}
		]
    });
}

Respond-to automatically determines the requested content-type in the following order:

1. Check the query for a "format" parameter. This can be one of the supported formats (xml, json and msg). This only works when no req.params.format is set!
2. Respond-to then checks for the req.params.format. Recommended: define a route as "/users/all.:format?".
3. Lastly, if none of the above steps resulted in a content-type, the Accept http header is used.
4. Default: json.

Documentation

Express

• respondTo(res, data, options = {}, callback = null)

Vanilla (without Express)

• respondTo(format, data, options = {}, callback)
• respondTo.json(data, options = {}, callback)
• respondTo.msg(data, options = {}, callback)
• respondTo.xml(data, options = {}, callback)

Express

respondTo(res, data, options = {}, callback = null)

This function aims at abstracting all serializing processes as much as possible. The use of this function is very similar to render (except for that it isn't an instance method).

Arguments

• res - An Express response. This always contains a reference to the original request so there's no need to explicitly include that.
• data - A serializable javascript object.
• options - Optional - The options-hash can be used for filtering keys.
• callback(err, data) - Optional - Note that when a callback is defined, res.send(data) is not called.

Vanilla (without Express)

respondTo(format, data, options = {}, callback)

You can use this function when you aren't using Express.

Arguments

• format - One of these: "json", "msg" and "xml".
• data - A serializable javascript object.
• options - Optional - The options-hash can be used for filtering keys.
• callback(err, data)

respondTo.json(data, options = {}, callback)

Arguments

• data - A serializable javascript object.
• options - Optional - The options-hash can be used for filtering keys.
• callback(err, data)

respondTo.msg(data, options = {}, callback)

Arguments

• data - A serializable javascript object.
• options - Optional - The options-hash can be used for filtering keys.
• callback(err, data)

respondTo.xml(data, options = {}, callback)

Arguments

• data - A serializable javascript object.
• options - Optional - The options-hash can be used for filtering keys.
• callback(err, data)