Call a method on a variable where the method name is in another variable

问题

<% @labels.each do |label| %>
    <input type="text" name="<%=label.name%>" value="<%=@car.(label.related_to) %>" class="big-font" style="width: <%=label.width%>px; top: <%=label.y_coor%>px; left: <%=label.x_coor%>px;" /> 
<% end %>

Hello guys, I'm new to rails so this should be a fairly easy question to answer.

The issue is here: <%=@car.(label.related_to) %>.

label.related_to holds the string "make". I'm trying to get it to do this pretty much: @car.make

Any idea guys?

Thanks, Alain

回答1:

Use send to send a message to an object:

@car.send(label.related_to)

If there is any chance of label.related_to not being a valid method for the object, you'll probably want to be prepared to catch the NoMethodError

回答2:

You could use try method.

<%= car.try(label.related_to) %>

try would try to call the method on car. However, if the method (ie. make) does not exist it would throw an error.

You could make use of respond_to? to ensure that the method exist:

<%= car.try(label.related_to) if car.respond_to?(label.related_to) %>

来源：https://stackoverflow.com/questions/4800836/call-a-method-on-a-variable-where-the-method-name-is-in-another-variable