复杂的Postgres SQL到RoR ORM

Question

环境：RoR 3.2 + Postgres

我创建了一个具有2个文本属性的services表： title和description

我要进行以下全文搜索：

SELECT * FROM (
        SELECT DISTINCT ON (s.id) s.*, 
            ts_rank_cd(s.service_tsv, query) AS rank 
        FROM to_tsquery('red | drawing | fun') AS query, 
            services AS s
        WHERE (s.service_tsv @@ query)
        ORDER BY s.id DESC
) AS sub ORDER BY rank DESC;

SQL语句就像一个超级按钮一样工作，但是如何将其转换为Rails ORM：

Service.joins(???).where(???).uniq 

Answer 1

Service.find_by_sql(%q{SELECT * FROM (
        SELECT DISTINCT ON (s.id) s.*, 
            ts_rank_cd(s.service_tsv, query) AS rank 
        FROM to_tsquery('red | drawing | fun') AS query, 
            services AS s
        WHERE (s.service_tsv @@ query)
        ORDER BY s.id DESC
) AS sub ORDER BY rank DESC})

此处的指南http://guides.rubyonrails.org/active_record_querying.html#finding-by-sql