[英]Rails: Sorting a query by params?
I am using running a simple find all and paginating with willpaginate, but I'd also like to have the query sorted by the user. 我正在使用运行一个简单的查找全部并使用willpaginate进行分页,但我也希望将查询按用户排序。 The first solution that came to mind was just use a params[:sort]
想到的第一个解决方案就是使用params [:sort]
http://localhost:3000/posts/?sort=created_at+DESC
@posts = Post.paginate :page => params[:page], :order => params[:sort]
But the problem with his approach is that the query is defaulting as sorting by ID and I want it to be created_at. 但他的方法的问题是查询默认为按ID排序,我希望它是created_at。
Is this a safe approach to sorting and is there a way to default to created_at? 这是一种安全的排序方法,有没有办法默认为created_at?
I'd use a named scope for providing the default order (available since Rails 2.1). 我使用命名范围来提供默认顺序(自Rails 2.1起可用)。
You'd add the scope in your Post model: 您将在Post模型中添加范围:
named_scope :ordered, lambda {|*args| {:order => (args.first || 'created_at DESC')} }
Then you can call: 然后你可以打电话:
@posts = Post.ordered.paginate :page => params[:page]
The example above will use the default order from the named_scope
( created_at DESC
), but you can also provide a different one: 上面的示例将使用
named_scope
( created_at DESC
)中的默认顺序,但您也可以提供另一个:
@posts = Post.ordered('title ASC').paginate :page => params[:page]
You could use that with Romulo's suggestion: 你可以在Romulo的建议中使用它:
sort_params = { "by_date" => "created_at", "by_name" => "name" }
@posts = Post.ordered(sort_params[params[:sort]]).paginate :page => params[:page]
If params[:sort]
isn't found in sort_params
and returns nil
then named_scope
will fall back to using the default order. 如果在
sort_params
找不到params[:sort]
并返回nil
那么named_scope
将回退到使用默认顺序。
Railscasts has some great info on named_scopes. Railscasts在named_scopes上有一些很棒的信息。
In general, the way to supply default values for Hash and Hash-like objects is to use fetch
: 通常,为Hash和Hash类对象提供默认值的方法是使用
fetch
:
params.fetch(:sort){ :created_at }
A lot of people just use ||
很多人只是使用
||
though: 虽然:
params[:sort] || :created_at
I prefer fetch
myself as being more explicit, plus it doesn't break when false
is a legitimate value. 我宁愿
fetch
自己为更加明确,加上当它不破false
是一个合法的值。
The Ruby idiom to set a default would be: 设置默认值的Ruby习语是:
@posts = Post.paginate :page => params[:page], :order => params[:sort] || "created_at"
But the approach isn't safe. 但这种方法并不安全。 The paginate method will not bother with a parameter like
"created_at; DROP DATABASE mydatabase;"
paginate方法不会打扰像
"created_at; DROP DATABASE mydatabase;"
这样的参数"created_at; DROP DATABASE mydatabase;"
. 。 Instead, you could use a dictionary of valid sort parameters (untested):
相反,您可以使用有效排序参数的字典(未经测试):
sort_params = { "by_date" => "created_at", "by_name" => "name" }
@posts = Post.paginate :page => params[:page], :order => sort_params[params[:sort] || "by_date"]
So that the URI becomes: 这样URI变为:
http://localhost:3000/posts/?sort=by_date
I prefer this idiom: 我更喜欢这个成语:
@posts = Post.paginate :page=>page, :order=>order
...
def page
params[:page] || 1
end
def order
params[:order] || 'created_at ASC'
end
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