DataValidatorListener

DataValidatorListener is one of the default listeners of MOST data models. Validates data objects against validation rules defined in model attributes.

Validation Rules

Each attribute may have a set of validation rules. These rules may validate data against:

Use default validation rules

In the following example price attribute has a validation which allows values between 0 to 1000:


{
    "name": "price",
    "title": "Price",
    "description": "The price of the product.",
    "type": "Number",
    "nullable":false,
    "validation": {
        "minValue":0,
        "maxValue":1000
    }
}

The following code snippet tries to save an object with a negative value in price:


 var obj = {
                "price": -23.45,
                "model": "FS2400",
                "name": "USB 3.0 Adapter"
            };
 context.model("Product").save(obj).then(function() {
               return done();
           }).catch(function(err) {
               return done(err);
           });

and the result is:


 {
     "code": "ERANGE",
     "model": "Product",
     "field": "price",
     "message": "The value should be between 0 to 1000."
 }

Use data type validation

A validation may be performed by using a pre-defined data type:


 {
     "name": "price",
     "title": "Price",
     "description": "The price of the product.",
     "type": "Number",
     "nullable":false,
     "validation": {
        "type":"NonNegativeNumber"
     }
 }

An operation tries to save a product with a negative price:


 var obj = {
                "price": -23.45,
                "model": "FS2400",
                "name": "USB 3.0 Adapter"
            };
 context.model("Product").save(obj).then(function() {
               return done();
           }).catch(function(err) {
               return done(err);
           });

and the result is:


 {
    "code": "EPATTERN",
    "model": "Product",
    "field": "price",
    "message": "The value should be a number greater or equal to zero."
}

The following list contains a set of pre-defined data types which may be used for data type validation:

Type	Description
NegativeInteger	An integer containing only negative values (..,-2,-1)
NegativeNumber	A number containing only negative values (..,-2,-1)
NonNegativeInteger	An integer containing only non-negative values (0,1,2,..)
NonNegativeNumber	An number containing only non-negative values (0,1,2,..)
NonPositiveInteger	An integer containing only non-positive values (..,-2,-1,0)
NonPositiveNumber	A number containing only non-positive values (..,-2,-1,0)
PositiveInteger	An integer containing only positive values (1,2,..)
PositiveNumber	A number containing only positive values (0.1,+1,2,..)
Float	Float data type is a single-precision floating point.
Email	A string which represents an email address (e.g. user@example.com)
Guid	A string which represents a global unique identifier (e.g. 21EC2020-3AEA-4069-A2DD-08002B30309D).
AbsoluteURI	A string which represents an absolute URI address (e.g. https://www.example.com/help?article=1001)
RelativeURI	A string which represents a relative URI address (e.g. /help?article=1001)
Time	A string which represents an instant of time that recurs every day (e.g. 13:20:45)
Date	Represents a date value.
DateTime	Represents a date and time value.
Duration	A string which represents a duration of time (e.g. P1Y1M10D, P10D, -P0Y1M10D2H15M30S etc)
IP	A string which represents an IPv4 address (e.g. 127.0.0.1)

Use custom validator

Value validation may be performed by custom validator which is being registered as follows:


 {
    "name": "price",
    "title": "Price",
    "description": "The price of the product.",
    "type": "Number",
    "nullable":false,
    "validation": {
      "validator":"./validators/price-validator"
    }
}

where price-validator is a module which exports a createInstance() method that returns an instance of a class which inherits DataValidator class.


 //# ./validators/price-validator
 var util = require("util"),
 most = require("most-data");

 function PriceValidator(attr) {
    this.attr = attr;
    PriceValidator.super_.call(this);
}
 util.inherits(PriceValidator, most.validators.DataValidator);
 PriceValidator.prototype.validateSync = function(val) {
    if (typeof val === 'number') {
        if (val<=0) {
            return {
                code:"EPRICE",
                "message":"A valid price must be always greater than zero."
            };
        }
    }
    else {
        return {
            code:"EPRICE",
            "message":"A valid price must be always a number greater than zero."
        };
    }
};
 exports.createInstance = function() {
    return new PriceValidator();
};

An operation tries to save a data object:


 var obj = {
        "price":-10.75,
        "model": "FS2USB3",
        "name": "USB 3.0 Adapter"
    };
context.model("Product").save(obj).then(function() {
       return done();
   }).catch(function(err) {
       return done(err);
   });

and the result is:


 {
    "code": "EPRICE",
    "model": "Product",
    "field": "price",
    "message": "A valid price must be always greater than zero."
}

A custom validator may use async validate(val,callback) method:


 PriceValidator.prototype.validate = function(val, callback) {
    this.getContext().model("Product")
    .where("price").lowerThan(val).count()
    .then(function(result) {
        if (result<=5) {
            return callback(null, {
                code:"EPRICE",
                "message":util.format("You have already 5 products with price lower than %s.", val)
            });
        }
        return callback();
    }).catch(function(err) {
        return callback(err);
    });
};

and the result may be:


 {
    "code": "EPRICE",
    "model": "Product",
    "field": "price",
    "message": "You have already 5 products with price lower than 10."
}

Constructor

new DataValidatorListener()

Source:

data-validator.js, line 975

Methods

beforeSave(event, callback)

Occurs before creating or updating a data object.

Parameters:

Name	Type	Description
`event`	DataEventArgs \| *	An object that represents the event arguments passed to this operation.
`callback`	function	A callback function that should be called at the end of this operation. The first argument may be an error if any occured.

Source:

data-validator.js, line 984