title: Passing props to React Router children routes
body: <p>I'm having trouble overcoming an issue with react router. The scenario is that i need to pass children routes a set of props from a state parent component and route.<br>
  what i would like to do is pass <code>childRouteA</code> its <code>propsA</code>, and pass <code>childRouteB</code> its <code>propsB</code>. However, the only way i can figure out how to do this is to pass <code>RouteHandler</code> both <code>propsA</code> and <code>propsB</code> which means every child route gets every child prop regardless of whether its relevant. this isnt a blocking issue at the moment, but i can see a time when i'd be using the two of the same component which means that keys on propA will overwritten by the keys by the keys of propB.  </p>
  
  <pre><code># routes
  routes = (
    &lt;Route name='filter' handler={ Parent } &gt;
      &lt;Route name='price' handler={ Child1 } /&gt;
      &lt;Route name='time' handler={ Child2 } /&gt;
    &lt;/Route&gt;
  )
  
  # Parent component
  render: -&gt;
    &lt;div&gt;
      &lt;RouteHandler {...@allProps()} /&gt;
    &lt;/div&gt;
  
  timeProps: -&gt;
    foo: 'bar'
  
  priceProps: -&gt;
    baz: 'qux'
  
  # assign = require 'object-assign'
  allProps: -&gt;
    assign {}, timeProps(), priceProps()
  </code></pre>
  
  <p>This actually works the way i expect it to. When i link to <code>/filters/time</code> i get the <code>Child2</code> component rendered. when i go to <code>/filters/price</code> i get the <code>Child1</code> component rendered. the issue is that by doing this process, <code>Child1</code> and <code>Child2</code> are both passed <code>allProps()</code> even though they only need price and time props, respectively. This can become an issue if those two components have an identical prop name and in general is just not a good practice to bloat components with unneeded props (as there are more than 2 children in my actual case).<br>
  <strong>so in summary</strong>, is there a way to pass the <code>RouteHandler</code> timeProps when i go to the time route (<code>filters/time</code>) and only pass priceProps to <code>RouteHandler</code> when i go to the price route (<code>filters/price</code>) and avoid passing all props to all children routes?</p>