Recipes

Introduction

This vignette walks the user through some applications of linne.

Shiny Inputs

Shiny developers often want to customise how shiny inputs look and feel, which can be a bother. Let’s say we want to change the label color of the textInput shiny input.

shiny::textInput(inputId = "text", "Label") 

cat(as.character(shiny::textInput(inputId = "text", "Label")))
#> <div class="form-group shiny-input-container">
#>   <label class="control-label" for="text">Label</label>
#>   <input id="text" type="text" class="form-control" value=""/>
#> </div>

One might be tempted to only use sel_id('text'), as demonstrated above, this would not work. We could instead use on of the infix operators select the child tag “label” of the input.

Linne$new()$
  rule(
    sel_id("text") %child% sel_tag("label"),
    color = "#f4a717"
  )$show_css()
#> #text label{
#>  color:#f4a717;
#> }

Now, just to demonstrate what is possible with CSS, say we want to change the font size of a specific option in a selectInput.

shiny::selectInput("select", "Select one:", choices = letters[1:3]) 

cat(as.character(shiny::selectInput("select", "Select one:", choices = letters[1:3])))
#> <div class="form-group shiny-input-container">
#>   <label class="control-label" for="select">Select one:</label>
#>   <div>
#>     <select id="select"><option value="a" selected>a</option>
#> <option value="b">b</option>
#> <option value="c">c</option></select>
#>     <script type="application/json" data-for="select" data-nonempty="">{}</script>
#>   </div>
#> </div>

We can again use a combination of selectors to select say, option “b”, to a different size.

Linne$new()$
  rule(
    sel_id("select") # inputId = "select"
      %child% 
      sel_attr("value", "b"), # value = 'b'
    color = "#f4a717"
  )$show_css()
#> #select [value='b']{
#>  color:#f4a717;
#> }

A good way to conceptualise the %child% operator is to think of it like one uses the pipe in the rvest package or how one might use the pipe in purrr: to gradually but surely go down the tree until the right node is selected.