- Schema validation module for Racer
- Uses z-schema, which supports JSON-Schema v4
- Schema validation executes in sync 'validate' hook, so you validate the actual result of operation
- Supports custom validators with async and sync logic
- Custom validators can preload data in async hook to use it later in sync
- Works only with JSON OT type
- Format functions should be sync
- For every op the whole doc validates each time, because it`s the only case when z-schema returns full path to wrong fields
Current 0.7 version of ShareJS has 4 hooks which are executed while operation is applied.
- async 'submit' hook - executes once before op is applied to data snapshot in db. This is convinient place to preload data and execute async validation logic. Be aware that you can not have result of operation here. It
s ok for some ops (model.set, model.add) because they ovewrites previous data (or add new), but for array mutators (model.push, model.pop, etc), string mutators (model.stringInsert, model.stringRemove) and increment (model.increment) its impossible to predict what will be the result data and we can not use some kinds of validators here because of this, like max, min, etc. That`s why we should use sync hook. - sync 'preValidate' hook - executes before op actually applied to snapshot. In high concurent cases it can be executed more than one time. We still does not have result data here, so it`s useless for us.
- sync 'validate' hook - executes after op is applied to snapshot, but before these changes are saved to db. Can be executed more than one time. It`s best place for schema validation logic as we have result data here which is not saved to db yet
- async 'after submit' hook - executes once after changes are saved to db. It`s useless for validation, but good to trigger some stuff
All schema validation logic executes in 'validate' hook. Custom validators have two methods: '.sync' - sync and executes in 'validate' hook and '.async' - async and executes in 'submit' hook. There can be one of them or both, also you can preload data in '.async' method to use it later in '.sync'
npm install racer-schema
var options = {
// Schemas use JSON-Schema format
schemas: {
users: {
title: 'Example Schema',
type: 'object',
properties: {
nickname: {
type: 'string',
format: 'xstring', // custom format
minLength: 1,
maxLength: 10
},
email: {
type: 'string',
format: 'email'
},
age: {
description: 'Age in years',
type: 'integer',
minimum: 0
},
roleId: {
type: 'string',
collection: 'roles', // additional field for 'join' custom validator
validators: ['join'] // custom validators
},
hobbies: {
type: 'array',
maxItems: 3,
items: {
type: 'string'
},
uniqueItems: true
}
},
required: ['email']
},
roles: {
type: 'object',
properties: {
name: {
type: 'string'
}
}
}
},
// JSON-Schema formats can be added here. They should be sync
formats: {
xstring: function(str) {
return str !== 'xxx';
}
},
// Custom validators
validators: {
// join - is working example of custom validator. It ensures that value is id of doc of specific collection
join: {
async: function(context, done) {
var id = context.value; // here is value for this op
if (!id) return done();
var collection = context.schema.collection; // context.schema - is schema of current property
var model = this.store.createModel();
var $entity = model.at(collection + '.' + id);
model.fetch($entity, function(err) {
if (err) return done(err);
if (!$entity.get()) {
return done(Error('No ' + collection + ' with id ' + id));
}
done();
});
}
},
// this is example of custom validator, that preloads data and uses it later
preload: {
async: function(context, done) {
var model = this.store.createModel(); // that`s how to get model
var $someData = model.at('some.path');
model.fetch($someData, function(err) {
if (err) return done(err);
var data = $someData.get();
done(null, data); // pass data as second parameter
})
},
sync: function(value, context) {
var data = context.data; // preloaded data is here
return true || false;
}
}
}
}
racer.use(require('racer-schema'), options);
// Or
derby.use(require('racer-schema'), options);
model.add('collection', doc, function(err) {
if (err) {
var errors = err.errors;
for (var i = 0; i < errors.length; i++) {
var error = errors[i];
var message = error.message; // Error message
var paths = error.paths; // Array of strings. Full path to error field
}
}
});
- racer-schema-example simple app with validation
Copyright (c) 2014 Vladimir Makhaev
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