xml-schema

Library to translate JSON to XML (and XML to JSON) using predefined JavaScript schemas.

For example, This library is used in opds-builder and onix-builder.

Installation

$ npm install xml-schema

API

var XMLSchema = require("xml-schema");

// Create a XML Schema
var xmlSchema = new XMLSchema(schema);

// Generate a XML string
var xml = xmlSchema.generate(data, options);

// Parse a XML string to some data
var data = xmlSchema.parse(xml);

Definition of schemas

{
    // Name of the element tag
    // If null, it will use the name of the fields
    tag: "myTag",

    // Use sub-value as text/raw node (default is undefined)
    inner: undefined,

    // Map of sub-elements defined by schema
    fields: {
        // Key can be the path of the property to get (eg: "a[0].b.c")
        // If "quot;, then the value is the one passed to the schema
        "key": anotherSchema
    },

    // Map of attributes
    // It works like "fields", options 'transform', 'default' are also available
    attributes: {
        "key2": {
            name: "attributeName",
            default: "attributeValue",

            // Transform value
            transform: function(v) { return v; },
            untransform: function(v) { return v; }
        }
    },

    // Map basic value (number, string, boolean) to object for the schema
    // This is usefull to make it easier to define both simple and complex data set
    map: {
        to: "key"
    },

    // Default value for the schema (default is undefined)
    default: "some stuff",

    // Transformation function for the value (default is identity)
    transform: function(v) { return v; },
    untransform: function(v) { return v; },

    // If true, Don't escape value when appened (default is false)
    raw: false,

    // If true, Append the resulting value as text (default is true)
    text: true,

    // If true, Append the resulting value as CDATA
    cdata: true,

    // If true: parse it as an array
    array: false,

    // If true: append empty element according to value
    bool: false
}

Generation

Options can be passed during xml generation to configure definition of the feed:

var xml = xmlSchema.generate(data, {
    // xml version to append in the header
    "version": "1.0",

    // encoding value to append in the header
    "encoding": "UTF-8",

    // If null, omits the standalone attribute
    "standalone": false,

    // If true, it will return a pretty xml string
    "pretty": true
})

Example to generate an ATOM feed

Define the JavaScript schemas for the ATOM feed:

var DATE = {
    transform: function(d) {
        return (new Date(d)).toISOString();
    }
};

var AUTHOR = {
    tag: 'author',
    fields: {
        name: {},
        uri: {},
        email: {}
    },
    map: {
        to: 'name'
    }
};

var LINK = {
    tag: 'link',
    attributes: {
        href: {},
        rel: {},
        type: {}
    },
    map: {
        to: 'href'
    }
};

var ENTRY = {
    tag: 'entry',
    fields: {
        title: {},
        updated: DATE,
        summary: {},
        links: LINK,
        authors: AUTHOR,
        author: AUTHOR,
        content: {
            raw: true,
            attributes: {
                type: {
                    default: "xhtml"
                }
            }
        }
    }
};

var FEED = {
    tag: 'feed',
    attributes: {
        xmlns: {
            default: "http://www.w3.org/2005/Atom"
        }
    },
    fields: {
        title: {},
        updated: DATE,
        links: LINK,
        entries: ENTRY,
        authors: AUTHOR,
        author: AUTHOR
    }
};

Initialize your XML schema processor:

var xmlSchema = new XMLSchema(FEED);

Convert JSON into XML based on the previously defined schema:

var xml = xmlSchema.generate({
    title: "Example Feed",
    links: [
        {
            href: "http://example.org/feed/",
            ref: "self"
        },
        "http://example.org/"
    ],
    entries: [
        {
            title: "Atom-Powered Robots Run Amok",
            updated: new Date(2015, 01, 15),
            links: [
                "http://example.org/2003/12/13/atom03",
                {
                    rel: "alternate",
                    type: "text/html",
                    href: "http://example.org/2003/12/13/atom03.html"
                },
                {
                    rel: "edit",
                    href: "http://example.org/2003/12/13/atom03/edit"
                }
            ],
            author: {
                name: "John Doe",
                email: "johndoe@example.com"
            },
            content: "<p>This is the entry content.</p>"
        }
    ]
},
// Options for generation
{
    version: '1.0',
    encoding: 'UTF-8'
});

Or parse some xml feed into a JS object:

var data = xmlSchema.parse(xml);