Objection.js, a SQL ORM

Slides from a talk given at LNUG May 2018

Transcript

1. Objection.js a SQL ORM Paul Jensen
2. HELLO ITS ME AGAIN!
3. Node.js has plenty of ORMs
4. Why consider another?
5. Sometimes a fresh take on an existing challenge can offer something better
6. So for your consideration, I offer you this…
7. Objection.js github.com/vincit/objection.js
8. Objection.js • Let’s you create models for tables with ES6 classes and define relationships between them • Make queries with Node’s async/await • Add validation to your models using JSON schema • Use eager-loading and transactions with your models • Work with nested documents in rows • Perform Graph Inserts and Upserts • and more…
9. Install
10. Knex knexjs.org
11. Knex • Rather than reinvent the wheel, Objection uses Knex, a powerful SQL query builder. • Besides building SQL queries, Knex is used to establish database connections, including pooling connections. • Also, it is used for managing database schemas via migrations.
12. Install a DB driver as well
13. Creating and managing database schemas
14. Creating and managing database schemas • Database migrations are a good pattern for managing changes to database schemas over time. • Objection.js defers to Knex for doing database migrations. • Knex depends on connecting to an existing database, so we’d need to create that first (unless it exists already).
15. Creating a database
16. Creating migrations • Migrations allow you to apply a change to a database schema in a step-by-step fashion. • The “up” action applies a change (creating a table, adding or modifying a column, appending an index). • The “down” action applies the reverse action of the change (e.g. if a migration’s “up” action creates a table, it’s equivalent “down” action will drop the table). • It provides a way to evolve a database schema over time, and be able to track the state of the database schema alongside the source code in version control (Git).
17. Creating migrations • Objection uses Knex’s in-built support for generating migrations and applying them, as well as being able to roll them back.
18. Creating migrations
19. Creating migrations
20. Creating migrations • Knex will create a migrations folder (unless it exists already) • It then creates a file in the migrations folder for the migration • The filename from the command line is prepended with a timestamp so that we can organise migrations in chronological order. • That determines the order in which migrations are executed.
21. The generated migration
23. Apply the migration
24. Apply the migration
26. Reversing the migration
27. Reversing the migration
29. Models
30. Models • Models are the wrappers around database tables • They help to encapsulate the business logic within those tables (relations, validations, indexes, triggers). • Objection.js allows you to create Models using ES classes
31. Task model
32. Queries
33. A simple SELECT query can be done with…
34. A more typical SELECT query can be done with…
35. INSERT queries can be done with…
36. UPDATE queries can be done with…
37. DELETE queries can be done with…
38. Relationships
39. Relationships • Objection.js provides a way to define the relationship between models that is powerful and flexible. • The relationships allow you to use other features like eager loading, as well as support Objection.js’ GraphQL plugin.
40. Relationships tasks id name due_by is_done created_at updated_at task_joins id dependent_id dependency_id created_at updated_at 1 ∞ ∞
44. You can also specify relationships through join tables
47. Example: Doing the dishes
51. Eager Loading
53. Lifecycle functions • A way to trigger functions when a record is inserted, updated, deleted, fetched or validated. • The lifecycle functions follow a pattern of beforeAction and afterAction.
54. Lifecycle functions • beforeValidate, afterValidate • beforeInsert, afterInsert • beforeUpdate, afterUpdate • beforeDelete, afterDelete • afterGet
55. Lifecycle functions You can execute functions that trigger during the lifecycle of inserting and updating records. You can determine whether they happen before or after the lifecycle event.
56. Lifecycle functions You can execute functions that trigger during the lifecycle of inserting and updating records. You can determine whether they happen before or after the lifecycle event.
57. Validations
58. Validations • Objection allows you to add validation logic to your models through using JSONSchema. • The validation logic will raise errors which can then be intercepted with try/catch
60. If you add jsonSchema to your models, you get to use some very cool plugins later on
61. Graph Inserts
62. Graph Inserts are cool
64. Quick demo
65. Plugins
66. Plugins • Objection comes with a few plugins that are worth checking out • Two which I can recommend are “objection-graphql” and “objection-password”
67. Objection-Password • Objection password adds quick local authentication to an application, using Bcrypt to apply the salting and hashing. • Setting it up is very simple - simply specify the number of hashing rounds for encrypting the password, and make your User model an extended class of the Password class
71. Objection-GraphQL • Objection-GraphQL allows you to put a GraphQL API on top of your Objection.js models with a few lines of code. • You will need to have your models using JSONSchema in order to get the benefits of this.
72. Quick little demo
73. Performance?
74. Do benchmark it, see what the performance impact is like
75. Wrap up
76. Objection.js github.com/vincit/objection.js
77. Knex knexjs.org
78. Objection-Password github.com/scoutforpets/objection-password
79. Objection-GraphQL github.com/vincit/objection-graphql
80. One more thing…
81. After 2½ glorious years at Starcount
82. I’m going to launch my own consultancy
83. ANEPHENIX
84. and I’m available for contracting from mid June
85. Thank You