adv-parser

Parser for special simplified syntax of json schema.

Default json schema

schema = {
    type: "object",
    additionalProperties: false,
    required: ['id', /* "name", */ 'enabled', 'list', 'user', 'enumOfStrings'],
    properties: {
        id: {
            type: "number",
        },
        name: {
            type: "string",
        },
        enabled: {
            type: "boolean",
        },
        list: {
            type: "array",
            items: {type: "number"}
        },
        user: {
            type: "object",
            additionalProperties: false,
            required: ['id', 'type'],
            properties: {
                id: {type: 'number'},
                type: {type: 'string'},
            }
        },
        enumOfStrings: {
            type: "string",
            enum: ["user", "guest", "owner"]
        },
    }
}

Simplified syntax of same schema

schema = {
    id: number,
    [name]: string,
    enabled: boolean,
    list: [number],
    user: {
        id: number,
        type: string,
    },
    enumOfStrings: "user" || "guest" || "owner",
}

• Usage
  • Schemas cache
  • Custom methods
  • Custom functions
  • Custom object inline options
• Optional object fields
• Array syntax
• Number patterns
• String patterns
• Inject external schema
• anyOf schema
• allOf schema
• Extend schema
• Switch syntax
• Pure syntax
• Schema methods
  • prop
  • props
  • merge
  • remove
  • required
  • notRequired
  • set
  • get
• Schema options as methods
• Object schema inline options

Usage

const parser = require('adv-parser');

let schema = parser(`{id: number}`);

// or as arrow function (which will be converted to string and parsed) 
// if you want free syntax highlighting

schema = parser(() => ({id: number}));

schema == {
    type: 'object',
    additionalProperties: false,
    required: ['id'],
    properties: {
        id: {type: 'number'}
    }
};

Schemas cache

const parser = require('adv-parser');
const defaultSchemas = require('adv-parser/schemas');

const schemas = {
    ...defaultSchemas
};

const schema1 = parser(`User = {id: number}`, {schemas});
const schema2 = parser(`Test.SubTest = {name: string}`, {schemas});
const schema3 = parser(Product => ({id: uuid}), {schemas});
const schema4 = parser(() => Company = {name: /^\w+$/}, {schemas});

schema1 == schemas.User;
schema2 == schemas['Test.SubTest'];
schema3 == schemas.Product;
schema4 == schemas.Company;

Custom methods

All methods work with the schema as AST. It gives you ability to create your own meta programming language

More about default methods see Schema methods and Schema options as methods

const parser = require('adv-parser');
const defaultMethods = require('adv-parser/methods');
const {set} = defaultMethods;

const schema = parser(`number.test(true)`, {
    methods: {
        ...defaultMethods,
        
        test: function (schema, args, params) {
            return set(schema, ['test', args[0]], params);
        }
    }
});

schema == {
    type: 'number',
    test: true,
};

Custom functions

You can define custom functions like

const parser = require('adv-parser');
const t = require('@babel/types');

const schema = parser(`{id: test(1, 2)}`, {
    functions: {
        test: function (args) {
            return t.numericLiteral(
                args.reduce((sum, item) => sum + item.value, 0)
            );
        }
    }
});

schema == {
    type: 'object',
    test: true,
    additionalProperties: false,
    required: ['id'],
    properties: {
        id: 3
    }
};

Custom object inline options

More about default object inline options see Object schema inline options

const parser = require('adv-parser');
const defaultObjectOptions = require('adv-parser/methods/object');
const set = require('adv-parser/methods/set');

const schema = parser(`{id: number, $test: true}`, {
    objectOptions: {
        ...defaultObjectOptions,
        
        test: function (schema, args, params) {
            return set(schema, ['test', args[0]], params);
        }
    }
});

schema == {
    type: 'object',
    test: true,
    additionalProperties: false,
    required: ['id'],
    properties: {
        id: {type: 'number'}
    }
};

Optional object fields

By default, all fields in an object are required. To make field optional just put it in brackets.

schema = {
    id: number,
    [name]: string,
}

schema == {
    type: "object",
    additionalProperties: false,
    required: ["id"],
    properties: {
        id: {type: "number"},
        name: {type: "string"},
    },
}

Array syntax

Here example of array where all items should be validated with one schema

schema = [number]

schema == {
  type: 'array',
  items: {type: 'number'}
}

Here example how we can validate items through many schemas

schema = [number || string || {id: number}]

schema == {
  type: 'array',
  items: {
    anyOf: [
      {type: 'number'},
      {type: 'string'},
      {
        type: 'object',
        additionalProperties: false,
        required: ['id'],
        properties: {
          id: {type: 'number'}
        }
      },
    ]
  }
}

Here index relative validation

schema = [number, string]

Which means that first element must be a number and second a string. Rest elements validation depends on array options like additionalItems. In this example valid will be: [1], [1, "abc"], [1, "abc", 2], []. Not valid: ["abc", 1], ["abc"]

schema == {
  type: 'array',
  items: [
    {type: 'number'},
    {type: 'string'}
  ]
}

You can add any array option with it methods

schema = [number, string].additionalItems(false)

schema == {
  type: 'array',
  items: [
    {type: 'number'},
    {type: 'string'}
  ],
  additionalItems: false,
}

If you need one index relative element validation than you can use items method like

firstNumber = [].items([number])
firstString = array.items([string])

firstNumber == {
  type: 'array',
  items: [{type: 'number'}]
}

firstString == {
  type: 'array',
  items: [{type: 'string'}]
}

This example means that at least one element in an array must be valid

list = [...string]
listOr = [...(string || boolean)]

list == {
  type: 'array',
  contains: {type: 'string'},
}
listOr == {
  type: 'array',
  contains: {anyOf: [{type: 'string'}, {type: 'boolean'}]},
}

Combination of index relative validation and contains

schema = [number, ...(string || boolean)]

schema == {
  type: 'array',
  items: [
    {type: 'number'}
  ],
  contains: {anyOf: [{type: 'string'}, {type: 'boolean'}]},
}

Number patterns

Instead of short number validator you can use one of following number patterns as value of object field.

• int number without floating-point
• positive positive number including 0
• negative negative number excluding 0
• id integer more than 0

schema = {
    id: id,
    price: positive,
    list: [int],
}

schema == {
    type: "object",
    additionalProperties: false,
    required: ['id', 'price', 'list'],
    properties: {
        id: {
            type: "integer",
            minimum: 1,
        },
        price: {
            type: "number",
            minimum: 0,
        },
        list: {
            type: "array",
            items: {
                type: "integer",
            }
        },
    },
}

String patterns

Instead of short string validator you can use one of following string patterns as value of object field.

• date full-date according to RFC3339.
• time time with optional time-zone.
• date-time date-time from the same source (time-zone is optional, in ajv it's mandatory)
• date-time-tz date-time with time-zone required
• uri full URI.
• uri-reference URI reference, including full and relative URIs.
• uri-template URI template according to RFC6570
• email email address.
• hostname host name according to RFC1034.
• filename name (words with dashes) with extension
• ipv4 IP address v4.
• ipv6 IP address v6.
• regex tests whether a string is a valid regular expression by passing it to RegExp constructor.
• uuid Universally Unique Identifier according to RFC4122.

Also, regexp will be converted to {pattern: "regexp"}

schema = {
    id: uuid,
    email: email,
    created_at: date-time,
    phone: /^\+?\d+$/,
    days: [date],
}

schema == {
    type: "object",
    additionalProperties: false,
    required: ['id', 'email', 'created_at', 'phone', 'days'],
    properties: {
        id: {
            type: "string",
            format: "uuid",
        },
        email: {
            type: "string",
            format: "email",
        },
        created_at: {
            type: "string",
            format: "date-time",
        },
        phone: {
            type: "string",
            pattern: "^\\+?\\d+$",
        },
        days: {
            type: "array",
            items: {
                type: "string",
                format: "date",
            }
        },
    }
}

Inject external schema

You can inject an external schema in a current schema.

User = {
    id: number,
    name: string,
}

schema = {
    action: 'update' || 'delete',
    user: User,
}

schema == {
  type: 'object',
  additionalProperties: false,
  required: ['action', 'user'],
  properties: {
    action: {
      type: 'string',
      enum: ['update', 'delete']
    },
    user: {
      type: 'object',
      additionalProperties: false,
      required: ['id', 'name'],
      properties: {
        id: {type: 'number'},
        name: {type: 'string'},
      }
    }
  }
}

anyOf schema

Instead of anyOf you can use || operator

schema = {
    data: User || Account || {type: "object"}
}

schema == {
    type: "object",
    additionalProperties: false,
    required: ['data'],
    properties: {
        data: {
            anyOf: [
                {/* schema of User */},
                {/* schema of Account */},
                {type: "object"},
            ]
        }
    }
}

allOf schema

Instead of allOf you can use && operator

schema = {
    data: User && Account && {type: "object"}
}

schema == {
    type: "object",
    additionalProperties: false,
    required: ['data'],
    properties: {
        data: {
            allOf: [
                {/* schema of User */},
                {/* schema of Account */},
                {type: "object"},
            ]
        }
    }
}

Extend schema

To extend you can use object spread operator

User = {
    id: number,
    data: string,
}

UserExtra = {
    name: string,
    created_at: date,
}

schema = {
   ...User,
   ...UserExtra,
  
   age: number, // add field
   data: undefined, // remove field
   created_at: date-time, // overwrite field
}

schema == {
   type: "object",
   additionalProperties: false,
   required: ['id', 'name', 'created_at', 'age'],
   properties: {
      id: {type: "number"},
      name: {type: "string"},
      created_at: {type: "string", format: "date-time"},
      age: {type: "number"},
   }
}

Also, you can overwrite validator options

schema = {
   ...User,
   type: "object",
   additionalProperties: true,
}

Important to add type: "object" it says to compiler that this object is pure ajv validator, not simplified version.

schema = {
   type: "object",
   additionalProperties: true,
   properties: {
      id: {type: "number"},
      data: {type: "string"},
   }
}

You extend even non object validators

phone = {
    type: "string",
    pattern: "^\\d+$"
}

schema = {
    ...phone,
  
    type: "string",
    maxLength: 20,
}

Switch syntax

This syntax useful in case when you write something like {...} || {...} || {...} but if validator found error then it throws tons of messages from each of that object. To help validator to figure out which object is responsible for current data you can use next syntax

schema = (
    (
        {action: 'create'} >>
        {
             name: string
        }
    )
    ||
    (
        {action: 'update'} >>
        {
            id: int, 
            name: string,
        }
    )
    ||
    (
        {action: 'delete'} >>
        {
            id: int
        }
    )
)

It will be converted to

schema = {
    if: {
        type: 'object',
        additionalProperties: true,
        required: ['action'],
        properties: {
            action: {const: 'create'}
        }
    },
    then: {
        type: 'object',
        additionalProperties: false,
        required: ['action', 'name'],
        properties: {
            action: {const: 'create'},
            name: {type: 'string'},
        }
    },
    else: {
        if: {
            type: 'object',
            additionalProperties: true,
            required: ['action'],
            properties: {
                action: {const: 'update'}
            }
        },
        then: {
            type: 'object',
            additionalProperties: false,
            required: ['action', 'id', 'name'],
            properties: {
                action: {const: 'update'},
                id: {type: 'integer'},
                name: {type: 'string'},
            }
        },
        else: {
            if: {
                type: 'object',
                additionalProperties: true,
                required: ['action'],
                properties: {
                    action: {const: 'delete'}
                }
            },
            then: {
                type: 'object',
                additionalProperties: false,
                required: ['action', 'id'],
                properties: {
                    action: {const: 'delete'},
                    id: {type: 'integer'},
                }
            },
            else: {
                oneOf: [
                    {
                        type: 'object',
                        additionalProperties: true,
                        required: ['action'],
                        properties: {
                            action: {const: 'create'}
                        }
                    },
                    {
                        type: 'object',
                        additionalProperties: true,
                        required: ['action'],
                        properties: {
                            action: {const: 'update'}
                        }
                    },
                    {
                        type: 'object',
                        additionalProperties: true,
                        required: ['action'],
                        properties: {
                            action: {const: 'delete'}
                        }
                    },
                ]
            }
        }
    }
}

Notice additionalProperties: true in each if: it means we are validating only part of object and additionalProperties: false in then: with same properties from if: which means we are validating hole object. Also we need last else: {oneOf: [...]} to throw error that none of if: is not matched.

Pure syntax

If you want to write pure json schema than use !! operator (all included schemas will be converted).

schema = {
    id: !!{type: 'number'},
    data: !!{
        type: 'object',
        properties: {
            name: string.minLength(1),
        },
    },
}

schema = {
    type: 'object',
    additionalProperties: false,
    required: ['id', 'data'],
    properties: {
        id: {type: 'number'},
        data: {
            type: 'object',
            properties: {
                name: {
                    type: 'string',
                    minLength: 1,
                },
            },
        },  
    },
}

You can mix pure syntax inside regular syntax

schema = {
    id: int,

    ...!!{
        additionalProperties: true,
        someOtherOption: true,
    },
}

schema = {
    type: 'object',
    additionalProperties: true,
    required: ['id'],
    properties: {
        id: {type: 'integer'}
    },
    someOtherOption: true,
}

Schema methods

Another great way to extend a schema is to use it methods.

Example schema

User = {
    id: number,
    [name]: string,
}

prop

Returns schema of property.

Here good way to reuse schema props, even if they super simple like number

schema = {
    id: User.prop('id')
}

schema == {
    id: number
}

props

Alias: pick

Returns "object" schema of props

schema = User.props('id', {name: 'full_name'})
 
schema == {
    id: number,
    [full_name]: string,
}

merge

Aliases: add, assign, extend

Returns extended schema

schema = User.merge({token: uuid})
 
schema == {
    id: number,
    [name]: string,
    token: uuid,
}

remove

Alias: omit

Returns schema without props

schema = User.remove('id')
 
schema == {
    [name]: string
}

required

Returns same schema, only with required props. Can take many props names.

schema = User.required('name')

schema == {
    id: number,
    name: string,
}

notRequired

Alias: optional

Make fields optional

schema = User.notRequired('id')

schema == {
    [id]: number,
    [name]: string,
}

set

Set schema option like additionalProperties or minLength

schema = User.set('additionalProperties', true)

schema == {
    type: "object",
    additionalProperties: true,
    required: ['id'],
    properties: {
        id: {type: "number"},
        name: {type: "string"},
    },
}

schema = {search: string.set('minLength', 3)}

schema == {
    search: {
        type: "string",
        minLength: 3,
    }
}

get

Return schema option value like minLength

schema = {
    search: string.set('minLength', User.prop('name').get('minLength'))
}

Schema options as methods

All schemas options are duplicated as methods

schema = {
    id: number.minimum(1),
    search: string.minLength(3).maxLength(20),
}

schema = User.additionalProperties(true).maxProperties(10)

Object schema inline options

All object options can be specified inline with properties with $ sign at the beginning of option name

schema = {
    id: number,
    
    $additionalProperties: true,
    $maxProperties: 10,
}

schema == {
    type: 'object',
    additionalProperties: true,
    maxProperties: 10,
    required: ['id'],
    properties: {
        id: {type: 'number'}
    }
}