Foundations.JSON.Schema

Schema.validate

You can use this API to determine if a JSON data object is valid JSON. Optionally, you can also validate it against a passed JSON schema object.

Syntax 

    Schema.validate( {instance object}, {schema object});

Parameters

Argument Required Type Description
instance object Yes any JSON data object.
schema object No any JSON schema object.

Returns 

{
  valid  : boolean,
  errors : [
      {
          property : string,
          message  : string
      }
  ]
}
Argument Required Type Description
valid Yes boolean Is instance object valid according to schema flag.
errors Yes array Array of inline objects. Returns empty array ("[]") if no errors.
errors[n].property No string Property that had the error.
errors[n].message No string Error message

Example 

var jsonlib = MojoLoader.require({name:"foundations.json", version: "1.0"});
var fjson = jsonlib["foundations.json"];
var jsonSchema = {"id":"com.palm.schema.test:1", 
  "type": "object", 
  "properties" : { "_kind" : {"type": "string", "value":"com.palm.schema.test:1"},
      "foo": {"type": "string", "description": "foo string"},
      "bar": {"type": "string", "description": "bar string"},
      "isMember": {"type": "boolean", "description" : "Is member flag" }
  }
};

var BadObj = {"_kind":"com.palm.schema.test:1", "foo":"myFoo", "bar":"myBar", "isMember": "true"};

Mojo.Log.info("FoundJSON: BadObj validate "+ JSON.stringify(fjson.Schema.validate(BadObj, jsonSchema)));

Example Output 

{"valid":false,"errors":[{"property":"isMember","message":"string value found, but a boolean is required"}]}

Schema.checkPropertyChange

Checks an object property for a valid value given its schema. Unlike the validate method, it assumes the passed schema object is valid.

Syntax 

    Schema.checkPropertyChange( {instance object}, {schema object}, "property");

Parameters

Argument Required Type Description
instance object Yes any JSON data object.
schema object Yes any JSON schema object. It is assumed this is valid.
property Yes string Name of schema property.

Returns 

{
  valid  : boolean,
  errors : [
      {
          property : string,
          message  : string
      }
  ]
}
Argument Required Type Description
valid Yes boolean Is instance object valid according to schema flag.
errors Yes array Array of inline objects. Returns empty array ("[]") if no errors.
errors[n].property No string Property that had the error.
errors[n].message No string Error message

Example 

var jsonlib = MojoLoader.require({name:"foundations.json", version: "1.0"});
var fjson = jsonlib["foundations.json"];
var jsonSchema = {"id":"com.palm.schema.test:1",
  "type": "object",
  "properties" : { "_kind" : {"type": "string", "value":"com.palm.schema.test:1"},
      "foo": {"type": "string", "description": "foo string"},
      "bar": {"type": "string", "description": "bar string"},
      "isMember": {"type": "boolean", "description" : "Is member flag" }
  }
};

var BadObj = {"_kind":"com.palm.schema.test:1", "foo":"myFoo", "bar":"myBar", "isMember": "true"};
var GoodObj = {"_kind":"com.palm.schema.test:1", "foo":"myFoo", "bar":"myBar", "isMember": true};
Mojo.Log.info("FoundJSON: checkPropertyChange good object "+ JSON.stringify(fjson.Schema.checkPropertyChange(GoodObj, jsonSchema, "isMember")));
Mojo.Log.info("FoundJSON: checkPropertyChange bad object "+ JSON.stringify(fjson.Schema.checkPropertyChange(BadObj, jsonSchema, "isMember")));

Example Output 

FoundJSON: checkPropertyChange good object {"valid":true,"errors":[]}, 
FoundJSON: checkPropertyChange bad object {"valid":false,"errors":[{"property":"isMember.isMember","message":"string value found, but a boolean is required"}]}