[英]Rails extract values with join associations
I have a rails join table between 2 models superhero
and superpower
. 我有两个模型
superhero
和superpower
之间的铁路连接表。 Now I have 3 different superpower id
and I want all the superheroes
which have all the selected superpowers
现在我有3个不同的
superpower id
,我希望所有superheroes
都拥有所有选定的superpowers
To do that I'm trying to do the following: 为此,我正在尝试执行以下操作:
matches = Superhero.all
matches = matches.joins(:superpowers).where('superpowers.id = ?', 17).where('superpowers.id = ?', 12).where('superpowers.id = ?', 6)
But this gives me an empty object even though I have superheroes
which have all the given superpowers
in my join table 但是这给了我一个空的对象,即使我有
superheroes
在我的连接表中拥有所有给定的superpowers
The query generated from the above is: 从上面生成的查询是:
SELECT "superheroes".* FROM "superheroes" INNER JOIN "superheroes_superpowers" ON "superheroes_superpowers"."superhero_id" = "superheroes"."id" INNER JOIN "superpowers" ON "superpowers"."id" = "superheroes_superpowers"."superpower_id" WHERE (superpowers.id = 17) AND (superpowers.id = 17) AND (superpowers.id = 12) AND (superpowers.id = 6)
So weirdly it tries to check for the superpower
with id 17 twice (but it shouldn't affect the result I think) and the rest of the query seems to be correct. 所以很奇怪它试图检查id为17的
superpower
两次(但它不应该影响我认为的结果),其余的查询似乎是正确的。
try using an in clause 尝试使用in子句
superpowers_ids = [17,12,6]
matches = Superhero.all
matches = matches.joins(:superpowers).where('superpowers.id in (?)', superpowers_ids)
Superhero.joins(:superpowers).where(superpowers: { id: [17,12,6] } )
This gives the following SQL query (formatted for readibility): 这给出了以下SQL查询(格式化为可读性):
SELECT "superheros".*
FROM "superheros"
INNER JOIN "superhero_superpowers" ON "superhero_superpowers"."superhero_id" = "superheros"."id"
INNER JOIN "superpowers" ON "superpowers"."id" = "superhero_superpowers"."superpower_id"
WHERE "superpowers"."id" IN (17, 12, 6)
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