data-defender

A node.js module to let you define and enforce data constraints.

The module is database-agnostic.

The module is also ideal for evaludating incoming request paramters for servers such as HTTP.

NOTE: This module alone does NOT store data in a database and it does NOT read from any database.

How To Install

npm install data-defencer

API

.returnError()

Enable the module to return errors instead of throwing exceptions.

.create(schemaName [string])

Returns a schema object to allow you to define constraints on each data property.

It will return an error if trying to create a schema that has already been created.

Example:

var defender = require('data-defender');
var example = defender.create('example');

example.define('id', {
    type: defender.DATATYPE.UNIQUE
});
example.define('name', {
    type: defender.DATATYPE.STR,
    default: 'No Name',
    validation: myValidationFunction,
    max: 30,
    min: 4
});

.get(schemaName [string])

Returns an already defined schema object.

It will return an error if trying to get a schema that has not been created.

Example:

var example = defender.get('example');

Schema Object

It is an instance of Struct class.

This object allows you to define constraints on each data property.

.define(PropertyName [string], constraints [object])

If there is an error, it will return an error.

constraints:

{
    type: [enum],
    default: [*default value],
    validation: [*function],
    max: [*number or date],
    min: [*number or date] 
}

type [enum]

Defines the data type of the property.

This is required.

The possible values are:

var defender = require('data-defender');

// number type
defender.DATATYPE.NUM;

// string type
defender.DATATYPE.STR;

// array type
defender.DATATYPE.ARR;

// object type
defender.DATATYPE.OBJ;

// unique type
defender.DATATYPE.UNIQUE;

// date type
defender.DATATYPE.DATE;

// boolean type
defender.DATATYPE.BOOL;

// modified time type
defender.DATATYPE.MOD;

NOTE 1: UNIQUE and MOD data type's value cannot be updated.

NOTE 2: MOD data type property will be updated automatically by updating other properties.

default [*default value]

An optional value to define a default value for the property.

NOTE: By setting this value to null, you can allow null value for this property.

validation [*function]

An optional function used to validated the value for the property.

The validation function is given the value as an argument.

NOTE: Validation function can only performce synchronous operations.

Example:

var defender = require('data-defender');
var validate = function (value) {
    // only odd numbers
    return value % 2 !== 0;
};
var example = defender.create('example');
example.define('oddNum', {
    type: defender.DATATYPE.NUM,
    validation: validate,
    default: 1,
    min: 1,
    max: 99
});

max [*number or date]

An optional value to define the maximum value for the property.

min [*number or date]

An optional value to define the minimum value for the property.

.lockSchema()

Locks the definition of schema. If you call .define() after invoking this function, it will throw an excetion.

.getPropertyNames()

Returns an array of defined property names.

.load(data [*object])

It loads the data and returns a data object.

If the given values do not meet the constraints defined by the schema, it will return an error.

NOTE: If you define a property that is UNIQUE and pass nothing to .load(), it will auto-generate a unique ID as a string.

Example:

var defender = require('data-defender');
var mySchema = defender.create('mySchema');
mySchema.define('id', {
    type: defender.DATATYPE.UNIQUE
});
mySchema.define('name', {
    type: defender.DATATYPE.STR,
    max: 30,
    min: 1
});
mySchema.define('age', {
    type: defender.DATATYPE.NUM,
    min: 0
});

var dbRecord = mySchema.load(dataFromDatabase);

Data Object

An instance of Data class. This object allows you to change the property values of the data loaded according to the schema constraints defined.

Example:

var defender = require('data-defender');
var mySchema = defender.create('mySchema');
mySchema.define('id', {
    type: defender.DATATYPE.UNIQUE
});
mySchema.define('name', {
    type: defender.DATATYPE.STR,
    max: 30,
    min: 1
});
mySchema.define('age', {
    type: defender.DATATYPE.NUM,
    min: 0
});

var dbRecord = mySchema.load(dataFromDatabase);
dbRecord.update('name', 'New Name');
dbRecord.update('age', dbRecord.get('age') + 4);

.update(propertyName [string], value [mix])

Updates the property value of the name given with the value passed to the function.

.get(propertyName [string])

Returns the current value of the given property.

.toJSON()

Returns all the property along with their values as an object.

Useful when you need to store the data to database etc.

Example:

var dataToSave = myData.toJSON();
saveToDatabase(dataToSave, callback);