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Backend Pattern Query
Ferris Tseng edited this page Jan 2, 2020
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Query objects store complex SQL queries, data aggregation, and filtering methods. 1
app/queries
- The Query object should take a relation as it's argument, that should enable the caller to control the scope of the query.
- Query objects should be composable. 2
- Should return an
ActiveRecord::Relation. 2
Note: In practice, it's difficult to achieve some of these desired qualities because Caseflow's data spans multiple databases.
Use the Service pattern if you are encapsulating complex logic that requires a read.
- 1: https://github.com/infinum/rails-handbook/blob/master/Design%20Patterns/Query%20Objects.md
- 2: https://medium.flatstack.com/query-object-in-ruby-on-rails-56ea434365f0
| Pattern | Description |
|---|---|
| Service | Alternative for database logic that requires writes |