Objection.js, a SQL ORM
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- Objection.js is a SQL ORM that allows you to define models for tables using ES6 classes and define relationships between them. It uses Knex for building SQL queries and managing database schemas. - The presentation demonstrates how to install Objection.js and Knex, create database migrations to manage schema changes, define models and relationships, perform queries, add validation, and use plugins like Objection-GraphQL and Objection-Password. - The speaker also announces that they are launching their own consultancy called ANEPHENIX and will be available for contracting work beginning in mid-June.
Objection.js, a SQL ORM
- 1. Objection.js a SQL ORM Paul Jensen
- 3. Node.js has plenty of ORMs
- 5. Sometimes a fresh take on an existing challenge can offer something better
- 6. So for your consideration, I offer you this…
- 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).
- 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.
- 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.
- 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.
- 44. You can also specify relationships through join tables
- 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.
- 73. Performance?
- 74. Do benchmark it, see what the performance impact is like
- 75. Wrap up 🌯
- 77. Knex knexjs.org
- 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