Empty dataTable after saving in shiny

Question

I create a reactive and editable matrix with dataTable in the shiny flex dashboard but when I try to save it as a CSV file it's empty

### Chart A

```{r}

      numericInput("num_hos", "Number of hospitals:", value = 2)
      numericInput("num_qua", "Number of quantities:", value = 2)
      actionButton("create", "Create an empty Matrix")
```



Column {data-width=350}
-----------------------------------------------------------------------

### Chart C

```{r}
data <- eventReactive(input$create,{
  matrix(nrow = input$num_hos+2,ncol = input$num_qua+1)
})

renderDataTable(data(),server = T,editable=list(target = "column"),
extensions = 'Buttons',options = list(dom = 'Blfrtip',buttons=c('copy', 'csv', 'excel', 'pdf', 'print'),
lengthMenu = list(c(10,25,50,-1),
  c(10,25,50,"All"))))
```

Answer 1

The code below works, but I use editable = list(target = "cell"), because I didn't manage with "column": I don't know how to validate the edits (with "cell" I just click somewhere).

---
title: "Untitled"
output: flexdashboard::flex_dashboard
date: "2023-03-20"
runtime: shiny_prerendered
---

```{r, context='setup', include=FALSE}
library(DT)
library(shiny)
```

### Chart A

```{r}
fillCol(
  height = 600, flex = c(NA, 1), 
  inputPanel(
    numericInput("num_hos", "Number of hospitals:", value = 2),
    numericInput("num_qua", "Number of quantities:", value = 2),
    actionButton("create", "Create an empty Matrix")
  ),
  DTOutput("dtable", height = "100%")
)
```

Column {data-width=350}
-----------------------------------------------------------------------

### Chart C

```{r, context='server'}
dat <- NULL
data <- eventReactive(input$create, {
  dat <<- matrix(nrow = input$num_hos+2, ncol = input$num_qua+1)
  dat
})

output[["dtable"]] <- renderDT({
  datatable(
    data(), 
    editable = list(target = "cell"),
    extensions = "Buttons", 
    options = list(
      dom = 'Blfrtip', 
      buttons=c('copy', 'csv', 'excel', 'pdf', 'print'),
      lengthMenu = list(c(10, 25, 50, -1), c(10, 25, 50, "All"))
    )
  )
})

proxy <- dataTableProxy("dtable")

observeEvent(input[["dtable_cell_edit"]], {
  dat <<- editData(dat, input[["dtable_cell_edit"]], proxy, rownames = FALSE)
})
```