Active Record Scopes and Arel
summary
Argues that using Arel instead of SQL fragments makes ActiveRecord scopes truly composable and database-portable, showing concrete code: Arel table columns with matches produce ILIKE on Postgres and LIKE elsewhere, in accepts arrays or ranges (generating IN or BETWEEN), and combining predicates with or or hash-style where avoids ambiguous column errors when merging scopes. Recommends class methods over lambda scopes for time-dependent or complex queries and mentions Squeel as a nicer predicate DSL.
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chapters (10)
- 0:00History of Rails Querying
- 2:11Introduction of named scopes
- 4:00Rails 3 querying changes
- 5:44Database compatibility issues
- 8:21Introduction to Arel
- 10:41Using Arel for complex queries
- 13:20Advanced Arel and hashes
- 15:55Avoiding SQL fragments
- 19:28Scope best practices
- 22:52Arel predicates and Squeel
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