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Fix query result of eager_load example in the guides. [ci-skip]

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Calling `eager_load` will execute a single query with a join, not two.
The original queries were probably the result of executing the code in
the console, where `books = Book.eager_load(:author).limit(10) `
would execute the query.
This commit is contained in:
Petrik 2024-05-29 16:36:24 +02:00
parent b9f814ad86
commit 11b25e0790
1 changed files with 4 additions and 5 deletions
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9
guides/source/active_record_querying.md
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@ -1744,13 +1744,12 @@ books.each do |book|
end
```
The above code will execute just **2** queries, as opposed to the **11** queries from the original case:
The above code will execute just **1** query, as opposed to the **11** queries from the original case:
```sql
SELECT DISTINCT books.id FROM books LEFT OUTER JOIN authors ON authors.id = books.author_id LIMIT 10
SELECT books.id AS t0_r0, books.last_name AS t0_r1, ...
FROM books LEFT OUTER JOIN authors ON authors.id = books.author_id
WHERE books.id IN (1,2,3,4,5,6,7,8,9,10)
SELECT "books"."id" AS t0_r0, "books"."title" AS t0_r1, ... FROM "books"
LEFT OUTER JOIN "authors" ON "authors"."id" = "books"."author_id"
LIMIT 10
```
NOTE: The `eager_load` method uses an array, hash, or a nested hash of array/hash in the same way as the `includes` method to load any number of associations with a single `Model.find` call. Also, like the `includes` method, you can specify conditions for eager loaded associations.