Schema to validate single object or collection

[Mathew]

I am new to JSON and JSON schema validation. I am using Draft-3 schema specification.   I have the following schema to validate a single employee object:   {     "$schema":"http://json-schema.org/draft-03/schema#",     "title":"Employee Type Schema",     "type":"object",     "properties":     {         "EmployeeID": {"type": "integer","minimum": 101,"maximum": 901,"required":true},         "FirstName": {"type": "string","required":true},         "LastName": {"type": "string","required":true},         "JobTitle": {"type": "string"},         "PhoneNumber": {"type": "string","required":true},         "Email": {"type": "string","required":true},         "Address":         {             "type": "object",             "properties":             {                 "AddressLine": {"type": "string","required":true},                 "City": {"type": "string","required":true},                 "PostalCode": {"type": "string","required":true},                 "StateProvinceName": {"type": "string","required":true}             }         },         "CountryRegionName": {"type": "string"}     } } And I have the following schema to validate an array of the same employee object:   {     "$schema": "http://json-schema.org/draft-03/schema#",     "title": "Employee set",     "type": "array",     "items":     {         "type": "object",         "properties":         {             "EmployeeID": {"type": "integer","minimum": 101,"maximum": 301,"required":true},             "FirstName": {"type": "string","required":true},             "LastName": {"type": "string","required":true},             "JobTitle": {"type": "string"},             "PhoneNumber": {"type": "string","required":true},             "Email": {"type": "string","required":true},             "Address":             {                 "type": "object",                 "properties":                 {                     "AddressLine": {"type": "string","required":true},                     "City": {"type": "string","required":true},                     "PostalCode": {"type": "string","required":true},                     "StateProvinceName": {"type": "string","required":true}                 }             },             "CountryRegionName": {"type": "string"}         }     } } Is it possible to create one single schema (I mean file) that would validate both a single employee instance and an rray of the employee object?     Sample data to test schemas:   {  "EmployeeID": 203,  "FirstName": "Squidward",  "LastName": "Tentacles",  "JobTitle": "Cashier",                  "Email": "Squidward.Tentacles&KrustyKrab.com",  "PhoneNumber": "(212)306-5000",                  "Address": {   "AddressLine": "15 Spongebob Parkway",   "City": "Bikini Bottom",   "PostalCode": "72834",   "StateProvinceName": "BB"  },  "CountryRegionName": "Down Under" }

[Geraint]

Are you familiar with using "$ref" to reference other schemas?

With "$ref", you can have something like this for your array:

{

    "type": "array",

    "items": {"$ref": "/schemas/path/to/employee"}

}

What I do very often is to embed an array definition like this inside the main schema, using "definitions":

{
    "$schema":"http://json-schema.org/draft-03/schema#",
    "title":"Employee Type Schema",
    "type":"object",

    "properties": {...},

    "definitions": {

        "array": {

            "type": "array",

            "items": {"$ref": "#"} // refers back to the root of the schema

        }

    }

}

Here, you can specify an array of items using "/schemas/path/to/employee#/definitions/array".  (There is nothing special about the "definitions" keyword, but it's reserved for this use, and it's a good convention.)

If you want something to be an array or a single item, then I would put a second entry in "definitions", using "oneOf":

{
    "$schema":"http://json-schema.org/draft-03/schema#",
    "title":"Employee Type Schema",
    "type":"object",

    "properties": {...},

    "definitions": {

        "array": {...},

        "singleOrArray": {

            "oneOf": [

                {"$ref": "#"}, // the root schema, defining the object

                {"$ref": "#/definitions/array"} // the array schema.

            ]

        }

    }

}

Hope that helps!

Geraint