Restrict input type in shiny field
<p>As it is, <code>numericInput</code> accepts both string and numeric inputs. If a string is entered it is converted to <code>NA</code> (try with the code below). Is there a way of not allowing the user to type a string in a numeric field in shiny?</p>

<pre><code>ui &lt;- fluidPage(
  numericInput("num", label = "text not allowed", value = 1),
  verbatimTextOutput("value")
)

server &lt;- function(input, output) {
  output$value &lt;- renderPrint({ input$num })      
}

shinyApp(ui = ui, server = server)
</code></pre>

<p>So far, I have added a text output next to the numeric input that warns the user that only numbers are accepted if she enters a string in a <code>numericInput</code> field. This solution is far from ideal for me. </p>

<p>I want it to be impossible for the user to enter a character value in a numeric field.</p>