jsonpolice

JSON Schema parser and validator

Usage no npm install needed!

<script type="module">
  import jsonpolice from 'https://cdn.skypack.dev/jsonpolice';
</script>

README

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.

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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
}