传递列表，经由参数

Question

到PostgreSQL，我使用Ruby通过这样的命令来调用通过外壳的PostgreSQL：

%x[ psql -A -F "," -o feeds/tmp.csv -f lib/sql/query.sql -v id_list="#{id_list}" ] 

query.sql的样子，但可以改变：

Select * 
From tbl_test 
Where id in (:id_list) 

查询应该解决为：

Select * 
From tbl_test 
Where id in ('a','b','c') 

在此先感谢。

Answer 1

# before 
-v id_list="#{id_list}" 

# after 
# `join` will separate the values in an array with the string provided 
# `map...` the block given to map will surround each item with single quotes 
-v id_list="#{id_list.map { |i| "'#{i}'" }.join(', ') }" 

# When `id` is an INTEGER you want the `IN` list specified without quotes 
# SELECT * FROM tbl_test WHERE id IN (1, 2, 3); 
-v id_list="#{id_list.map(&:to_i).join(', ') }"