Ruby-on-rails 在 Rails 查询中包含 LIKE 子句的最佳方法是什么？
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What's the best way to include a LIKE clause in a Rails query?
提问by Peter Nixey
What's the best way to include a LIKE clause in a Rails query i.e. something along the lines of (the completely incorrect):
在 Rails 查询中包含 LIKE 子句的最佳方法是什么，即类似于（完全不正确）的内容：
Question.where(:content => 'LIKE %farming%')
回答by Ammar
You'd use the syntax:
你会使用语法：
Question.where("content LIKE ?" , "%#{farming}%")
回答by numbers1311407
If this is Rails 3 you can use Arel's matches. This has the advantage of being database agnostic. For example:
如果这是 Rails 3，您可以使用 Arel 的matches. 这具有与数据库无关的优点。例如：
Question.where(Question.arel_table[:content].matches("%#{string}%"))
This is somewhat clunky, but easily extracted to scopes, e.g.:
这有点笨重，但很容易提取到范围，例如：
class Question
def self.match_scope_condition(col, query)
arel_table[col].matches("%#{query}%")
end
scope :matching, lambda {|*args|
col, opts = args.shift, args.extract_options!
op = opts[:operator] || :or
where args.flatten.map {|query| match_scope_condition(col, query) }.inject(&op)
}
scope :matching_content, lambda {|*query|
matching(:content, *query)
}
end
Question.matching_content('farming', 'dancing') # farming or dancing
Question.matching_content('farming', 'dancing', :operator => :and) # farming and dancing
Question.matching(:other_column, 'farming', 'dancing') # same thing for a different col
Of course to join with "AND" you could just chain the scopes.
当然，要加入“AND”，您可以将范围链接起来。
Edit: +1 to metawhere and squeel though (haven't tried latter but it looks cool) They both add this type of functionality and much more.
编辑：+1 到 metawhere 和 squeel（还没有尝试过后者，但看起来很酷）它们都添加了这种类型的功能等等。
回答by Mario Uher
If you want really sexy conditions and and don't have problems with external dependencies, I highly recommend MetaWhereand it's successor Squeel:
如果你想要真正性感的条件并且没有外部依赖的问题，我强烈推荐MetaWhere和它的继任者Squeel：
# MetaWhere
Question.where(:content.like => '%farming%')
# MetaWhere with operators overloaded
Question.where(:content =~ '%farming%')
# Squeel
Question.where { :content.matches => '%farming%' }
# Squeel with operators overloaded
Question.where { :content =~ '%farming%' }
