jsonpolice

A Javascript library implementing the JSON Schema draft 7.

The library can optionally decorate parsed objects in order to have them return default values defined in the schema, for undefined properties.

Install

$ npm install jsonpolice

create(dataOrUri, options)

Create a new instance of schema validator.

• dataOrUri, the schema to parse or a fully qualified URI to pass to retriever to download the schema
• options, parsing options, the following optional properties are supported:
  • scope (required), the current resolution scope (absolute URL) of URLs and paths.
  • registry, an object to use to cache resolved id and $ref values. If no registry is passed, one is automatically created. Pass a registry if you are going to parse several schemas or URIs referencing the same id and $ref values.
  • retriever, a function accepting a URL in input and returning a promise resolved to an object representing the data downloaded for the URI. Whenever a $ref to a new URI is found, if the URI is not already cached in the store in use, it'll be fetched using this retriever. If not retriever is passed and a URI needs to be downloaded, a no_retriever exception is thrown. Refer to the documentation of jsonref for sample retriever functions to use in the browser or with Node.js.

The function returns a Promise resolving to a new instance of Schema. Once created, a schema instance can be used repeatedly to validate data, calling the method Schema.validate.

Example

import * as jp from 'jsonpolice';

(async () => {

  const schema = jp.create({
    type: 'object',
    properties: {
      d: {
        type: 'string',
        format: 'date-time'
      },
      i: {
        type: 'integer'
      },
      b: {
        type: [ 'boolean', 'number' ]
      },
      c: {
        default: 5
      }
    }
  });
  
  try {
    const result = await schema.validate({
      d: (new Date()).toISOString(),
      i: 6,
      b: true
    });
  } catch(err) {
    // validation failed
  }

})();

Schema.validate(data [, options])

Validates the input data

• data, the data to parse
• options, validation options, the following optional properties are supported:
  • setDefault, if true returns the default value specified in the schema (if any) for undefined properties
  • removeAdditional, if true deletes properties not validating against additionalProperties, without failing
  • context, if set to read deletes writeOnly properties, if set to write delete readOnly properties

Returns a decorated version of data, according to the specified options.

Example

Using the following schema:

{
  type: 'object',
  properties: {
    d: {
      type: 'string',
    },
    i: {
      type: 'integer'
    },
    b: {
      type: [ 'boolean', 'number' ]
    },
    c: {
      default: 5
    }
  }
}

And parsing the following data:

var output = schema.validate({
  d: 'test',
  i: 10,
  b: true
});

Produces the following output:

{
  "d": "test",
  "i": 10,
  "b": true,
  "c": 5
}