Persistor

Description

Persistor is a subclass of SuperType that serializes to and reconstitutes from mongoDB or PostgreSQL.

Installation

It is automatically installed with Amorphic

Example

First create some object templates (many-to-many example):

var ObjectTemplate = require('supertype').default;
var PersistObjectTemplate = require('persistor')(ObjectTemplate, null, ObjectTemplate);

var Customer = PersistObjectTemplate.create("customer:Customer", {
email: {type: String},
firstName: {type: String},
middleName: {type: String},
lastName: {type: String}
});

var Account = PersistObjectTemplate.create("account:Account", {
init: function (number, title, customer) {
this.number = number;
this.title = title;
if (customer)
this.addCustomer(customer);
},
addCustomer: function(customer, relationship) {
var role = new Role(customer, this, relationship);
this.roles.push(role);
customer.roles.push(role);
},
number: {type: Number},
title: {type: Array, of: String, max: 4}
});

var Role = PersistObjectTemplate.create("role:Role", {
init: function (customer, account, relationship) {
this.customer = customer;
this.account = account;
if (relationship)
this.relationship = relationship;
},
relationship: {type: String, value: "primary"},
customer: {type: Customer}
});

Customer.mixin({
roles: {type: Array, of: Role, value: [], fetch: true}
});

Account.mixin({
roles: {type: Array, of: Role, value: [], fetch: true}
});

Next you need a schema but this schema only defines the foreign key relationships

var collections = {
customer: {
children: {
roles: {template: Role, id:"customer_id"}
}
},
account: {
children: {
roles: {id:"account_id"}
}
},
role: {
parents: {
customer: {id: 'customer_id'},
account: {id: 'account_id'}
}
},
};

In the schema, the high level properties, customer, account and role are the names of the documents and must match the
names of the documents in the template definition which is always :

var Role = PersistObjectTemplate.create("role:Role", {

Then open your database and set the schema

return Q.ninvoke(MongoClient, "connect", "mongodb://localhost:27017/testpersist").then(function (db) {
PersistObjectTemplate.setDB(db);
PersistObjectTemplate.setSchema(collections);
return Q(db);
}).then ....;

Create some objects

var sam = new Customer("Sam", "M", "Elsamman");
var karen = new Customer("Karen", "", "Burke");
var account = new Account(123, ['Sam Elsamman', 'Karen Burke'], sam);
account.addCustomer(karen, "joint");

Persist the top level and any connected dirty objects will automatically persist as well, managing all foreign
keys needed to maintain the relationships.

sam.persistSave().then(function() {
// id inserted after saving
return Q(sam._id);
}).then ....

And retrieve stuff back by id, cascading down to fetch the roles as well.

Customer.getFromPersistWithId(customer_id, {roles: true}).then (function (customer) {
// Customer object complete with collection of role objects fetched and instantiated
});

Or fetch with a query

Customer.getFromPersistWithQuery({lastName: "Elsamman"}, {roles: true}).then (function (customer) {
// Customer object complete with collection of role objects fetched and instantiated
});

The account object connected to the fetched role is also automatically when a role is fetched because the template specified
{fetch: true}. Had it not been specified you would manually fetch the related account object like this

Customer.getFromPersistWithId(customer_id, {roles: true}).then (function (customer) {
customer.role[0].fetch({account: true}).then(function() {
// Now you can reference customer.role[0].account
});
});

Debugging the container

1. Remove local node_modules folder and delete package-lock file and run the following commnd to launch the container in debug mode.
npm run test:docker:debug

If you are using Visual Studio Code, you can use the following setting to attach to the debugging container.
{
"type": "node",
"request": "attach",
"name": "persistor_debug",
"port": 5858,
"localRoot": "${workspaceFolder}",
"remoteRoot": "/app"
}

Debugging in the local environment.

2. Make sure to install the mongodb and postgres locally and set the environment variables from the test.local.env file.
If you are using Visual Studio Code, you can use the following setting to debug.
{
"type": "node",
"request": "launch",
"name": "Mocha Tests",
"program": "${workspaceFolder}/node_modules/mocha/bin/_mocha",
"args": [
"-u",
"tdd",
"--timeout",
"999999",
"--colors",
"${workspaceFolder}/test"
],
"envFile": "${workspaceFolder}/test.local.env",
"internalConsoleOptions": "openOnSessionStart"
}

License

Persistor is licensed under the MIT license