json-schema-aopromise

JSON Schema validator and filter aspect for
aopromise aspect oriented programming toolkit, using tv4.
Useful for type-hint-like parameter validation.

Quick start

$3

You can use the aspect by passing the schemas for each argument of the wrapped function you want to validate

``javascript
aop = require('aopromise');
aop.register('validated', require('json-schema-aopromise').Validator);

var userSchema = getUserSchema();

userService.save = aop()
.validated(userSchema) // schema for the first argument, you may an array for multiple arguments
.fn(function (user) {
// user object is valid
});

userService.save({
"id": "invalidId", // not a number
"name": "John Doe",
"gender": "DUCK!" // not in enum
}).catch(function (e) { // will fail, so
return console.error(e.message, e.explanation)
});


// declaring schema
// more info at http://json-schema.org/examples.html
function getUserSchema() {
return {
"title": "User schema",
"type": "object",
"properties": {
"id": {
"type": "integer"
},
"name": {
"type": "string"
},
"email": {
"type": "string"
},
"gender": {
"type": "string",
enum: ['male', 'female']
}

},
"required": ["name"]
};
}
`

#### Options for validator
`javascript
{
filter: [true|false] // Whether to filter out properties that are no specified on the schema. The default uses additionalProperties as switch of the feature.
}
`

$3


You may want to filter your function output. An example is when you have users stored in the database and only
a limited set of properties are public for the users of your API, for example skip the password hash.
In this case you may want to have a limited schema with the public fields of the user and filter the output of the result
with that.
`javascript
var aop = require('aopromise');
aop.register('filtered', require('../lib/json-schema-aopromise').Filter);

userService.get = aop()
.filtered(getLimitedUserSchema())
.fn(function (id) {
return {
"id": id,
"name": "Joe",
"email": "secret@email.com" // this should be filtered out
}
});


userService.get(123).then(function(user){
console.log(user);
// outputs user without email:
// { id: 123, name: 'Joe' }
});

function getLimitedUserSchema() {
var userSchema = getUserSchema(); // using user schema implementation above
delete userSchema.properties.email;
return userSchema;
}

`

#### Options for result filter
`javascript
{
validate: [true|false] // Whether to validate the result against the schema. If true, the promise will be rather rejected if the result does not match the schema. Default false.
}
`

$3


The library exposes a typed validation error that can be catched with bluebird promises:
`javascript
var ValidationError = require('json-schema-aopromise').ValidationError;
userService.save({
"id": "invalidId", // not a number
"name": "John Doe",
"gender": "DUCK!" // not in enum
}).catch(ValidationError, function (err) { // will fail, so
console.error(err.message); // outputs "Validation of arguments failed."
console.error(err.explanation); // outputs: /id: Invalid type: string (expected integer)
// /gender: No enum match for: "DUCK!"
}).catch(function(err){ // others
// ...
})
`

$3

#### 0.3
BREAKING CHANGE: thrown error is not an array anymore. Error array is now available in the errors validationErrors property.
`javascript
// THIS IS NOT WORKING ANYMORE
userService.save(...).catch(ValidationError, function (err) {
err.forEach(...);
})
// WORKS
userService.save(...).catch(ValidationError, function (err) {
err.validationErrors.forEach(...);
})
``