sworm

SWORM

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

• Microsoft SQL Server (MSSQL)
• PostgreSQL
• MySQL

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:

var sworm = require('sworm');

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

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

});

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 () {

  ...

});

Connection options:

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

• config connection options passed to the database driver of choice. See configuration options for: SQL Server, MySQL, PostgreSQL.

• url a connection URL passed to the postgres driver. See the pg url format.

• 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()

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.

• 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',

  function: addPerson(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({...}, [options]);

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

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.
});

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

var records = db.query(sql, [parameters]);

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.

Model Queries

var entities = model.query(sql, [parameters]);

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