CODEWITHSUNDEEP
sqlruby-on-railsactiverecordscope
Meliborn
Meliborn

Reputation: 6645

Lazy scopes in Rails

As we know, scopes starts load when calling. So this expression

articles = Article.published
articles.newest

gets 2 queries. Yes, we can do such this

articles = Article.published.newest

But what if I need conditions? If foo == bar than continue chain.

Upvotes: 2

Views: 1131

Answers (3)

Sean Hill
Sean Hill

Reputation: 15056

You are incorrect. In your example, the two lines:

articles = Article.published
articles.newest

This will not generate two queries. The reason that you are able to continue chaining is that these calls will return an ActiveRecord::Relation, which will only execute a query on traversal or a select few other method calls, like count, sum, or other aggregation methods.

If you are looking at this from the console, it will appear that each line is generating a query. This is because in the console, there is an implicit inspect call being called after every evaluation, which will generate a query.

Upvotes: 11

Benjamin M
Benjamin M

Reputation: 24577

Conditions in the same table?

@a = Article.where("published = true AND foo = bar").order("publishing_date desc").limit(1)

If you need eager loading with multiple tables, use the includes(...) method.

Upvotes: 0

xdazz
xdazz

Reputation: 160973

You could just do like below:

articles = foo == bar ? Article.published.newest : Article.published

Upvotes: 0

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