Today I Learned

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Nested table querying with ActiveRecord

Sometimes you need to query a joined table in ActiveRecord. This can be easily done via the hash syntax:

User.where(greetings: {text: "HOWDY"}).to_sql

=> SELECT "users".* FROM "users" WHERE ("greetings"."text" = 'HOWDY')

Note: the key here (greetings) is pluralized because we’re referencing a table name and not a potential relationship that ActiveRecord knows about.

Note: I’ve ommited a join to the greetings table that would have this query make sense

Cool: so we can do that but there’s even an alternative way to handle this using dot notation

User.where("greetings.text": "HOWDY"}).to_sql

=> SELECT "users".* FROM "users" WHERE ("greetings"."text" = 'HOWDY')

Under the hood, ActiveRecord will convert dots from the string key and interpret them as table and column names.

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