Mc-schema NPM | npm.io

mc-schema

Very Fast JSON Schema Validator. See benchmark generated with z-schema benchmark tool.

This package is collection of ideas json-model and some code z-schema.

It compile JSON schema to JavaScript code, like template engines (see below).

Using

var mcSchema = require('mc-schema');

var result = mcSchema.validate({
    type: 'object',
    required: ['foo', 'bar']
}, {
    foo: 1,
    bar: 2
});

result.valid; // true

result = mcSchema.validate({
    type: 'object',
    required: ['foo', 'bar']
}, {
    foo: 1
});

result.valid; // false

Precompile

For best speed you can compile schemas before validating:

var schema = mcSchema.compile({
    type: 'object',
    required: ['foo', 'bar']
});

schema.validate({}).valid; // false

Compilation looks like this:

var schema = {
    type: 'number',
    minimum: 2
};

// compiles to function like

function validate(data) {
    if (typeof data != 'number') { throw 'invalid type'; }

    if (data > 2) { throw 'minumum'; }
}

Schema `default` property

It can be define default properties for undefined values by schema if property is required:

var data = {};
var schema = mcSchema.compile({
    type: 'object',
    required: ['foo']
    properties: {
        foo: {
            default: 1
        },
        bar: {
            default: 2
        }
    }
});

var result = schema.validate(data);

result.valid === true;
result.errors.length === 0;
result.data === data;
//
// data === {
//  foo: 1 // only `foo` sets to `default` because it is required
// }
//

Coerce after validate

You can fix invalid JSON objects by using schema.coerce. It tries to fix value when INVALID_TYPE error happens, delete invalid properties and items on OBJECT_ADDITIONAL_PROPERTIES or ARRAY_ADDITIONAL_ITEMS errors. In other cases it deletes all invalid values. If attemption to fix value is failed, it returns undefined;

Simple case:

var schema = mcSchema.compile({
    type: 'object',
    additionalProperties: false,
    required: ['foo'],
    properties: {
        foo: { type: 'boolean' },
        bar: { type: 'string' }
    }
});

var result = schema.coerce({
    foo: 'false',
    bar: 1,
    baz: {}
});

// result = {
//  foo: false,
//  bar: '1'
// };

var result2 = schema.coerce({
    bar: 'baz'
});

//
// result2 = undefined
//

Complex case:

var schema = mcSchema.compile({
    type: 'object',
    additionalProperties: false,
    properties: {
        foo: {
            type: 'array',
            additionalItems: false,
            items: [{ type: 'boolean' }]
        },
        bar: {
            type: 'array',
            items: {
                type: 'object',
                required: ['baz'],
                properties: {
                    baz: {
                        type: 'integer'
                    }
                }
            },
            minItems: 1 
        }
    }
});

var result = schema.coerce({
    foo: ['false', 1],
    bar: [{}]
});

// result = {
//  foo: [false]
// }
// 
var result2 = schema.coerce({
    foo: ['false', 1],
    bar: [{ baz: '2.1'}]
});

// result2 = {
//  foo: [false],
//  bar: [{baz: 2}]
// }

Custom type coerce

To add custom type or redefine coerce, use mcSchema.addTypeCoerce:

mcSchema.addTypeCoerce('object', function(value) {
    try {
        return JSON.parse(value);
    } catch (e) {}
});

var schema = mcSchema.compile({
    type: 'object',
    properties: {
        foo: { type: 'number' }
    }
});

var result = schema.coerce('{"foo":"1"}');
// result = { foo: 1 }

Collect errors

By default mc-schema stops validating after first error. Use collectErrors option for prevent it behaviour in validate:

var schema = mcSchema.compile({
    type: 'array',
    items: {
        type: 'integer'
    }
});

var result = schema.validate([1, 2, '3', false], { collectErrors: true });
// result.errors = [
//  {
//      code: 'INVALID_TYPE',
//      expected: ['integer'],
//      actual: 'boolean',
//      dataPath: '#/3'
//  },
//  {
//      code: 'INVALID_TYPE',
//      expected: ['integer'],
//      actual: 'string',
//      dataPath: '#/2'
//  }
// ]