sworm

SWORM

A very lightweight write only Node.js ORM, with support for:

• Microsoft SQL Server (MSSQL)
• PostgreSQL
• MySQL
• Oracle DB
• Sqlite 3

NPM

npm install sworm

Then install a database driver, one of:

npm install mssql
npm install pg
npm install mysql
npm install oracledb
npm install sqlite3

See sworm in NPM.

Write Only?

The features in this module are mostly for writing graphs of related entities. Querying, on the other hand, is done with raw SQL so you can do it fast. See the query API for details.

This ORM avoids some of the largest issues experienced in other ORMs:

• query performance is too opaque
• N+1 queries are frequently the default
• configuring eager and lazy loading is tricky
• one-to-many, many-to-one, many-to-many relationships are notoriously difficult to get right
• lifecycle management of sessions and identity maps is rarely pleasant
• check out the massive generated SQL statements!

Just write SQL, you know how.

Example

var person = db.model({table: 'people'});
var address = db.model({table: 'addresses'});

var bob = person({
  name: 'bob',
  address: address({
    address: 'Fremantle'
  })
});

bob.save()

Produces:

-------- people ----------
| id | name | address_id |
--------------------------
| 11 | bob  | 22         |
--------------------------

------- addresses ------
| id | address         |
------------------------
| 22 | Fremantle       |
------------------------

Connection

Connect:

db.connect(config? : {}, fn? : () -> Promise);

• config database connection configuration, see below
• fn if passed, connect() will connect to the database, run the function, then disconnect. Ensure that fn returns a promise.

You can pass connection configuration to the sworm.db() function, or to the db.connect() function.

var sworm = require('sworm');

var db = sworm.db({
  driver: 'pg',
  config: {
    user: 'user',
    password: 'password',
    host: 'localhost',
    database: 'databasename'
  }
});

var person = db.model({table: 'people'});

var bob = person({name: 'Bob'});

// sworm connects at the first database interaction
bob.save();

Or define models then connect:

var sworm = require('sworm');

var db = sworm.db();

var person = db.model({table: 'people'});

db.connect({
  driver: 'mssql',
  config: {
    user: 'user',
    password: 'password',
    server: 'localhost',
    database: 'databasename'
  }
}).then(function () {

  ...

});

Or connect, run some code and then disconnect:

var sworm = require('sworm');

var db = sworm.db(config);

var person = db.model({table: 'people'});

db.connect(function () {

  // connected

  var bob = person({name: 'bob'});
  return bob.save().then(function () {
    ...
  });
}).then(function () {
  
  // disconnected

});

Connection options:

• driver, one of 'mssql', 'mysql', 'pg', 'oracle' or 'sqlite'.

• config configuration passed to the selected driver:

  • mysql

    See: https://github.com/felixge/node-mysql#connection-options

    {
      user: 'username',
      password: 'password',
      host: 'localhost',
      database: 'database name'
    }
    

  • mssql

    See: https://github.com/patriksimek/node-mssql#configuration-1

    {
      user: 'username',
      password: 'password',
      server: 'localhost',
      database: 'databaseName'
    }
    

  • pg

    See also the url option below.

    See: https://github.com/brianc/node-postgres/wiki/pg#connectstring-connectionstring-function-callback

    The driver will use connection pooling if you pass pool: true.

    {
      user: 'username',
      password: 'password',
      host: 'localhost',
      database: 'database name',
      pool: true
    }
    

  • oracle

    See: getConnection() For options see Oracledb Properties

    The driver will use connection pooling if you pass pool: true.

    By default the driver is set to autoCommit = true, you can pass options: { autoCommit: false} to turn this off again.

    {
      user: 'username',
      password: 'password',
      connectString: 'localhost/XE',
      pool: true,
    
      options: {
        // options to set on `oracledb`
        maxRows: 1000
      }
    }
    

    The driver can also use an existing pool:

    {
      pool: pool // from oracledb.createPool(config, cb),
    
      options: {
        // options to set on `oracledb`
        maxRows: 1000
      }
    }
    

  • sqlite

    See: https://github.com/mapbox/node-sqlite3/wiki/API#new-sqlite3databasefilename-mode-callback

    {
      filename: 'filename or :memory:'
    }
    

• url a connection URL, the following are supported

  • pg - postgres://user:password@host:5432/database. See the pg url format.
  • oracle - oracle://user:password@host:1521/sid&maxRows=100000&pool=true

• setupSession a function that is passed the db to setup the session before any queries are run.

  setupSession: function (db) {
    return db.query("alter session set time_zone = 'UTC'");
  }
  

• log: either true to log SQL statements with console.log()

  Can also be a function for custom logging:

  function (sql, params) {
    // sql == 'select * from people where name = @name'
    // params == {name: 'bob'}
  }
  

  Defaults to false, no logging.

Close

Close the connection after use:

db.close()

Debug

This module uses debug, so you can easily see what's happening under the hood by setting a DEBUG environment variable.

DEBUG=sworm node myapp.js

There are various schemes you can use:

• sworm all queries
• sworm:results all results
• sworm:mssql exact query passed to mssql
• sworm:mysql exact query passed to mysql
• sworm:pg exact query passed to postgres
• sworm:oracle exact query passed to oracle
• sworm:sqlite exact query passed to sqlite3

Models

var createEntity = db.model(options);

options can contain the following:

• table (undefined) the name of the table to save entities to

• id ('id') the name of the identity column. This can be an array of id columns for compound keys, or false if there is no id column.

• idType (oracledb.NUMBER) for oracledb the type of the identity column, for e.g. oracledb.STRING.

• foreignKeyFor a function that returns a foreign key field name for a member (see Relationships), defaults to:

  function foreignKeyFor(fieldName) {
    return fieldName + '_id';
  }
  

createEntity is a function that can be used to create entities from the model.

Model Methods

Any other properties or functions on the options object are accessible by entities.

var address = db.model({
  table: 'addresses',

  addPerson: function(person) {
    this.people = this.people || [];
    person.address = this;
    this.people.push(person);
  }
});

var fremantle = address({address: 'Fremantle'});
fremantle.addPerson(person({name: 'bob'}));

Entities

The entity constructor takes an object with fields to be saved to the database.

var person = db.model({...});

var bob = person({
  name: 'bob'
}, [options]);

Where options can have:

• saved: if true will update the entity (if modified) on the next save(), if false will insert the entity on the next save(). Default false.
• modified: if true (and if saved is true), will update the entity on the next save() regardless if it has been modified.

Save

var promise = entity.save([options]);

Inserts or updates the entity into the table. If the entity already has a value for its identity column, then it is updated, if not, it is inserted.

Objects know when they've been modified since their last insert or update, so they won't update unless a field is modified. You can force an update by passing {force: true}.

save() returns a promise.

Identity

entity.identity()

Returns the ID of the entity, based on the identity column specified in the model.

Changed

entity.changed()

Returns true if the object has been modified since the last save().

Relationships

Entities can contain fields that are other entities. This way you can build up graphs of entities and save them all in one go.

Many to One

When entity A contains a field that is entity B, then B will be saved first and B's ID will be set and saved with A.

The foreign key of the member will be saved on the field name member_id. So address will have a foreign key of address_id. See the foreignKeyFor option in Models.

var person = db.model({table: 'people'});
var address = db.model({table: 'addresses'});

var bob = person({
  name: 'bob',
  address: address({
    address: "15 Rue d'Essert"
  })
});

bob.save().then(function () {
  assert(bob.address_id == address.id);
});

In SQL:

-------- people ----------
| id | name | address_id |
--------------------------
| 11 | bob  | 22         |
--------------------------

------- addresses ------
| id | address         |
------------------------
| 22 | 15 Rue d'Essert |
------------------------

One to Many

When entity A contains a field that is an array that contains entities B and C. Then entity A will be saved first, followed by all entities B and C.

This allows entities B and C to refer to entity A, as they would in their tables.

var person = db.model({ table: 'people' });
var address = db.model({ table: 'addresses' });

var bob = person({name: 'bob'});
var jane = person({name: 'jane'});

var essert = address({
  address: "15 Rue d'Essert",
  people: [bob, jane]
});

bob.address = essert;
jane.address = essert;

essert.save().then(function () {
  // all objects saved.
});

Alternatively, we can return the people in the address using a function. When the address is saved, the people function will be called with the owner address as this, then we can set the foreign key for the people. Following the save() the results of the function will be saved as an array on the object.

var person = db.model({ table: 'people' });
var address = db.model({ table: 'addresses' });

var essert = address({
  address: "15 Rue d'Essert",
  people: function(addr) {
    return [
      person({ name: 'bob', address: addr }),
      person({ name: 'jane', address: addr })
    ];
  }
});

essert.save().then(function () {
  // all objects saved.
  // essert.people == [{name: 'bob', ...}, {name: 'jane', ...}]
});

Notice that whether we use an array or a function, the field itself is never saved to the database, only the entities inside the array.

In SQL:

-------- people ----------
| id | name | address_id |
--------------------------
| 11 | bob  | 22         |
| 12 | jane | 22         |
--------------------------

------- addresses ------
| id | address         |
------------------------
| 22 | 15 Rue d'Essert |
------------------------

Many to Many

Many-to-many is just a combination of one-to-many and many-to-one:

var person = db.model({ table: 'people' });
var personAddress = db.model({ table: 'people_addresses', id: ['address_id', 'person_id'] });
var address = db.model({ table: 'addresses' });

function personLivesInAddress(person, address) {
  pa = personAddress({person: person, address: address});

  person.addresses = person.addresses || [];
  person.addresses.push(pa);

  address.people = address.people || [];
  address.people.push(pa);
}

var bob = person({name: 'bob'});
var jane = person({name: 'jane'});

var fremantle = address({
  address: "Fremantle"
});
var essert = address({
  address: "15 Rue d'Essert"
});

personLivesInAddress(bob, fremantle);
personLivesInAddress(jane, fremantle);
personLivesInAddress(jane, essert);

Promise.all([essert.save(), fremantle.save()]);

In SQL:

-- people ---
| id | name |
-------------
| 11 | bob  |
| 12 | jane |
-------------

------- addresses ------
| id | address         |
------------------------
| 22 | 15 Rue d'Essert |
| 23 | Fremantle       |
------------------------

---- people_addresses ----
| address_id | person_id |
--------------------------
| 22         | 12        |
| 23         | 12        |
| 23         | 11        |
--------------------------

Queries

db.query(sql, [parameters]).then(function (records) {
});

Where:

• sql is the SQL query, can be a query (i.e. select), or a command (update, insert, stored proc)
• parameters. If sql contains parameters in the form of @paramName the corresponding property on the parameters object will be substituted into the SQL, doing any escaping necessary.

For select queries, returns an array of objects, containing the fields of each record.

db.query('select * from people where name = @name', {name: 'Bob'}).then(function (results) {
  console.log(results);

  /*
     [
       {id: 2, name: 'Bob'}
     ]
   */
}); 

Stored Procedure Example

db.query('myProcName @param1, @param2', {param1: 'a', param2: 'b'});

Model Queries

model.query(sql, [parameters]).then(function (entities) {
});

Same as db.query() but records returned are turned into entities of the model that can subsequently be modified and saved.

person.query('select * from people where id = @id', {id: 1}, function (people) {
  var bob = people[0];
  bob.name = 'Jack';
  return bob.save();
});

Statements

Statements are just like queries but they don't bother to parse or log the results.

db.statement(query, [params, [options]]);

Transactions

You can insert update or query the database using transactions. Transactions can be used in two forms, explicitly running db.begin(), db.commit() and db.rollback(), or by calling db.transaction(fn) with a function that will commit automatically if it didn't fail.

The explicit form:

db.begin().then(() => {
  var bob = person({name: 'bob'});
  return bob.save();
}).then(() => {
  db.rollback();
  // or
  db.commit();
});

The implicit form:

db.transaction(() => {
  var bob = person({name: 'bob'});
  return bob.save();
});

db.begin([options]);

Begin the transaction

• options a string that is appended to the database's begin command, for e.g. db.begin('isolation level read committed') will result in the sql begin isolation level read committed.

db.rollback();

Rollback the transaction

db.commit();

Commit the transaction

db.transaction(options? : String, fn : () => Promise)

• options a string that is appended to the database's begin command, for e.g. db.begin('isolation level read committed') will result in the sql begin isolation level read committed.
• fn a function that is executed after the transaction has begun. The function is expected to return a promise, if resolved, the transaction will be committed, if rejected, the transaction will be rolled back.

db.transaction(() => {
  // this transaction will be rolled back
  return db.query('update people set name = @name', {name: 'jane'}).then(() => {
    throw new Error('uh oh!');
  });
});

db.transaction(() => {
  // this transaction will be committed
  return db.query('update people set name = @name', {name: 'jane'});
});

Accessing the Connection

You can access the underlying driver's connection after the database has connected of course through db.driver.connection.

Options

You can pass options to the database driver when executing a query

db.query(sql, parameters, [options])

• SQLite3
  • multiline or exec runs the exec() method on the connection which executes multiple lines, see exec. Note that this method ignores any query parameters passed in.
• Oracle
  • formatRows if false will not format rows as lower case and will return the raw oracledb results. Formatting rows may be a performance issue for large result sets.
  • any other options are passed to oracledb's execute method.

Development

Tests

The only thing slightly awkward about this project are the test environments for each database. I've tried to make this as easy as possible however:

• sqlite3 works out of the box on most if not all platforms
• mysql, postgres and oracle instances can be found in the docker-compose.yml file. Install docker, make it run somehow, then run docker-compose up -d. This will download and start each of the databases necessary to run the tests. The tests look for the $DOCKER_HOST environment variable to see where the docker host is, if it's in a VM or somewhere else, otherwise the databases are expected to be on localhost, running on their default ports.
• mssql is less friendly, and all I ask is that it's running on a machine called windows (hack your /etc/hosts file if necessary), with a fresh database called sworm, with user user and password password.

Each database can be tested individually by running mocha test/{mssql,mysql,postgres,oracle,sqlite}Spec.js. All of them with simply npm test.

Nevertheless, this project is almost entirely covered with tests and I expect any pull request to have tests that demonstrate any new feature or bugfix.