ruby 使用哈希值呈现 ERB 模板
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Render an ERB template with values from a hash
提问by Shrikant Sharat
I must be overlooking something very simple here but I can't seem to figure out how to render a simple ERB template with values from a hash-map.
我一定在这里忽略了一些非常简单的东西，但我似乎无法弄清楚如何使用哈希映射中的值呈现一个简单的 ERB 模板。
I am relatively new to ruby, coming from python. I have an ERB template (not HTML), which I need rendered with context that's to be taken from a hash-map, which I receive from an external source.
我对 ruby 比较陌生，来自 python。我有一个 ERB 模板（不是 HTML），我需要使用从外部源接收的哈希映射中获取的上下文来呈现它。
However, the documentation of ERB, states that the ERB.resultmethod takes a binding. I learnt that they are something that hold the variable contexts in ruby (something like locals()and globals()in python, I presume?). But, I don't know how I can build a binding object out of my hash-map.
但是，ERB 的文档指出该ERB.result方法采用binding. 我才知道，他们是保持着可变背景的红宝石东西（像locals()和globals()在python，我相信？）。但是，我不知道如何从哈希映射中构建绑定对象。
A little (a lot, actually) googling gave me this: http://refactormycode.com/codes/281-given-a-hash-of-variables-render-an-erb-template, which uses some ruby metaprogramming magic that escapes me.
一点点（实际上很多）谷歌搜索给了我这个：http: //refactormycode.com/codes/281-given-a-hash-of-variables-render-an-erb-template，它使用了一些 ruby 元编程魔法逃脱我。
So, isn't there a simple solution to this problem? Or is there a better templating engine (not tied to HTML) better suited for this? (I only chose ERB because its in the stdlib).
那么，这个问题难道没有简单的解决方案吗？或者是否有更好的模板引擎（不绑定到 HTML）更适合于此？（我只选择 ERB 因为它在 stdlib 中）。
采纳答案by Dave Newton
I don't know if this qualifies as "more elegant" or not:
我不知道这是否符合“更优雅”的条件：
require 'erb'
require 'ostruct'
class ErbalT < OpenStruct
def render(template)
ERB.new(template).result(binding)
end
end
et = ErbalT.new({ :first => 'Mislav', 'last' => 'Marohnic' })
puts et.render('Name: <%= first %> <%= last %>')
Or from a class method:
或者从一个类方法：
class ErbalT < OpenStruct
def self.render_from_hash(t, h)
ErbalT.new(h).render(t)
end
def render(template)
ERB.new(template).result(binding)
end
end
template = 'Name: <%= first %> <%= last %>'
vars = { :first => 'Mislav', 'last' => 'Marohnic' }
puts ErbalT::render_from_hash(template, vars)
(ErbalT has Erb, T for template, and sounds like "herbal tea". Naming things is hard.)
（ErbalT 有 Erb，T 表示模板，听起来像“凉茶”。命名很难。）
回答by Moriarty
require 'erb'
require 'ostruct'
def render(template, vars)
ERB.new(template).result(OpenStruct.new(vars).instance_eval { binding })
end
e.g
例如
render("Hey, <%= first_name %> <%= last_name %>", first_name: "James", last_name: "Moriarty")
# => "Hey, James Moriarty"
Update:
更新：
A simple example without ERB:
一个没有 ERB 的简单例子：
def render(template, vars)
eval template, OpenStruct.new(vars).instance_eval { binding }
end
e.g.
例如
render '"Hey, #{first_name} #{last_name}"', first_name: "James", last_name: "Moriarty"
# => "Hey, James Moriarty
Update 2: checkout @adam-spiers comment below.
更新 2：在下面结帐@adam-spiers 评论。
回答by Phrogz
If you can use Erubisyou have this functionality already:
如果您可以使用Erubis，则您已经拥有此功能：
irb(main):001:0> require 'erubis'
#=> true
irb(main):002:0> locals = { first:'Gavin', last:'Kistner' }
#=> {:first=>"Gavin", :last=>"Kistner"}
irb(main):003:0> Erubis::Eruby.new("I am <%=first%> <%=last%>").result(locals)
#=> "I am Gavin Kistner"
回答by Tom Copeland
Ruby 2.5 has ERB#result_with_hashwhich provides this functionality:
Ruby 2.5ERB#result_with_hash提供了以下功能：
$ ruby -rerb -e 'p ERB.new("Hi <%= name %>").result_with_hash(name: "Tom")'
"Hi Tom"
回答by Lev Lukomsky
The tricky part here is not to pollute binding with redundant local variables (like in top-rated answers):
这里的棘手部分是不要用冗余局部变量来污染绑定（例如在最高评价的答案中）：
require 'erb'
class TemplateRenderer
def self.empty_binding
binding
end
def self.render(template_content, locals = {})
b = empty_binding
locals.each { |k, v| b.local_variable_set(k, v) }
# puts b.local_variable_defined?(:template_content) #=> false
ERB.new(template_content).result(b)
end
end
# use it
TemplateRenderer.render('<%= x %> <%= y %>', x: 1, y: 2) #=> "1 2"
# use it 2: read template from file
TemplateRenderer.render(File.read('my_template.erb'), x: 1, y: 2)
回答by asfer
回答by Alex D
If you want to do things very simply, you can always just use explicit hash lookups inside the ERB template. Say you use "binding" to pass a hash variable called "hash" into the template, it would look like this:
如果您想非常简单地做事，您总是可以在 ERB 模板中使用显式哈希查找。假设您使用“binding”将一个名为“hash”的哈希变量传递到模板中，它看起来像这样：
<%= hash["key"] %>
