I have a shiny app with a css style-sheet. Within the shiny app i use reactable and reactable.extras to capture text inputs.

library(shiny)
library(dplyr)
library(reactable)
library(reactable.extras)

df <- tibble(text_col = rep(NA, 5))

tweak_css <- function(file = "style.css") {

  tags$link(rel= "stylesheet",
            type = "text/css",
            href = file) |>
            tags$head()

}


shinyApp(
  ui = fluidPage(
    tweak_css(),
    reactable_extras_dependency(),
    reactableOutput("react"), 
    dataTableOutput("out")
  ),
  server = function(input, output) {
    rv <- reactiveValues(data = df)
    
    
      
    output$react <- renderReactable({
      reactable(
        rv$data,
        
        columns = list(
          
          text_col = colDef(
          cell = text_extra(id = "text", 
                            class = "text-extra"))
        )
        
      )
    })
    
    text_d <- reactive({ input$text}) %>% debounce(3000)    
    
    observeEvent(text_d(), {
      
      rv$data[text_d()$row, text_d()$column] <- text_d()$value
      
    })   
    
    output$out <- renderDataTable({
      rv$data
    })
  }
)

The accompanying style-sheet defines the size of the text input field. I fail to manage preventing text overflow.

.text-extra {
  
  width: 80px;
  height: 80px;
  word-break: break-word;
  
}

I tried almost everything described here How to prevent text from overflowing in CSS? but it does not solve the problem. What can i do that the user can enter text with line breaks?

EDIT:

The use of DT seems not suitable since my original application has some more columns with checkboxes included.

What can i do that the user can enter text with line breaks?

You could wrap the text_extra function and give it the correct style.

Code

library(shiny)
library(dplyr)
library(reactable)
library(reactable.extras)

df <- tibble(text_col = rep(NA, 5))

text_extra <- function(id = NULL, class = NULL) {
  function(value, index, name) {
    div(
      class = class,
      style = "white-space: pre-wrap !important; word-break: break-all !important;",
      textAreaInput(
        inputId = paste0(id, "_", index, "_", name),
        label = NULL,
        value = value,
        resize = "none",
        width = "80px",
        height = "80px"
      )
    )
  }
}
shinyApp(
  ui = fluidPage(
    reactable_extras_dependency(),
    reactableOutput("react"), 
    dataTableOutput("out")
  ),
  server = function(input, output) {
    rv <- reactiveValues(data = df)
    
    output$react <- renderReactable({
      reactable(
        rv$data,
        columns = list(text_col = colDef(cell = text_extra(id = "text", class = "text-extra")))
      )
    })
    
    text_d <- reactive({ input$text}) %>% debounce(3000)    
    
    observeEvent(text_d(), {
      
      rv$data[text_d()$row, text_d()$column] <- text_d()$value
      
    })   
    
    output$out <- renderDataTable({
      rv$data
    })
  }
)

With datatable and checkboxes

library(shiny)
library(dplyr)
library(DT)

# Create sample data
df <- tibble(
  text_col = rep(NA, 5),
  yes_no = rep(FALSE, 5)
)

shinyApp(
  ui = fluidPage(
    DTOutput("table")
  ),
  
  server = function(input, output, session) {
    rv <- reactiveValues(data = df)
    
    output$table <- renderDT({
      datatable(
        rv$data,
        editable = list(
          target = 'cell',
          disable = list(columns = c(2))  # Enable editing for text column only
        ),
        selection = "none",
        options = list(
          columnDefs = list(
            list(
              targets = 2,  # yes_no column index (1-based)
              render = JS("
                function(data, type, row, meta) {
                  if (type === 'display') {
                    return '<input type=\"checkbox\"' + 
                           (data ? ' checked' : '') + 
                           ' onclick=\"(' + function(el) {
                             var cell = el.parentNode;
                             var row = cell.parentNode;
                             var rowIdx = row.rowIndex;
                             var colIdx = cell.cellIndex;
                             Shiny.setInputValue(\'checkbox_click\', 
                               {row: rowIdx, checked: el.checked, col: colIdx}, 
                               {priority: \'event\'}
                             );
                           } + ')(this)\">';
                  }
                  return data;
                }")
            )
          )
        )
      )
    })
    
    observeEvent(input$table_cell_edit, {
      info <- input$table_cell_edit
      rv$data[info$row, info$col] <- info$value
    })
    
    observeEvent(input$checkbox_click, {
      info <- input$checkbox_click
      print(info)
      rv$data$yes_no[info$row] <- info$checked  # Add 1 because JS is 0-based
      print(rv$data)
    })
  }
)