Rails erb Json视图条件渲染

Question

When I try this, I get {a: 1, b:} for c not present. When c is present I get {a:1,b:1} which is right. But how can I hide the node b conditionally so that I could only get {a:1}?

{"a":   <%= json @teams.count %>
,"b":   <%= json @teams.num if @c.present? %>}

Answer 1

You can pass a ruby hash to json and it will figure it out correctly

<%= json( a: @teams.count, b: (@teams.num if @c.present?) ) %>

The problem with your method is that you are trying to render the string yourself, but nil is being rendered as blank space instead of an empty string '' . You could theoretically fix it like this:

{"a":   <%= json @teams.count %>
,"b":   <%= json(@c.present? ? @teams.num : '' %>}

but you can avoid most of the hassle if you use the first method.