How to Change 'Maximum Upload Size Exceeded' Restriction in Shiny and Save User File Inputs

How to change 'Maximum upload size exceeded' restriction in Shiny and save user file inputs?

Quoting Joe Cheng from this shiny-discuss post

By default, Shiny limits file uploads to 5MB per file. You can modify this limit by using the shiny.maxRequestSize option. For example, adding options(shiny.maxRequestSize=30*1024^2) to the top of server.R would increase the limit to 30MB.

Changing the size and storing an image file uploaded by the user with Shiny

We can use magick::image_scale() to resize the images and then save them in the working directory (or maybe create temp files) because drive_update takes a path as media argument.

Version avoiding code repetitions:

library(shiny)
library(magick)
library(tidyverse)
library(googledrive)

n_showphotos <- 3

ui <- fluidPage(
    fileInput("loadphotos", label = "Carregar fotos", multiple = TRUE),
    actionButton("do", "Carregar"),
    tagList(
    map(str_c('showphotos', 1:n_showphotos), ~imageOutput(.x, height = '200px')))
)

server <- function(input, output, session) {
    
    observeEvent(input$do, {
        

        lst <- NULL
        for (i in 1:length(input$loadphotos[,1])) {
            lst[[i]] <- input$loadphotos[[i, 'datapath']]
        }
        
        lst %>%
            map2(str_c('showphotos', 1:length(.)),~ { output[[.y]] <- renderImage({list(src = .x, height="200")},deleteFile = FALSE) })
        
        #a list with all the images but resized to 200
        #"x200" to resize by height
        images_resized <- lst %>% 
            map(~image_scale(image = image_read(.x), "200"))
        
        #images will be located in the project directory or home folder (getwd() to get working directory if in doubt)
        images_resized %>%
            walk2(str_c('image', 1:length(.)), ~ image_write(.x, path = str_c(.y, '.png'), format = "png"))
        
        
        #        drive_upload(image1.png, 
        #               as_id("https://drive.google.com/drive/u/1/folders/1qj0eeee...")
   
    })
    
}

shinyApp(ui, server)

With code repetition:

library(tidyverse)
library(googledrive)
library(shiny)
library(magick)

ui <- fluidPage(
    fileInput("loadphotos", label="Carregar fotos", multiple=T),
    actionButton("do", "Carregar"),
    imageOutput("showphotos1", height="200px"),
    imageOutput("showphotos2", height="200px"),
    imageOutput("showphotos3", height="200px")
)

server <- function(input, output, session) {
    observeEvent(input$do, {
        lst <- NULL
        req(input$loadphotos)
        for(i in 1:length(input$loadphotos[,1])) {
            lst[[i]] <- input$loadphotos[[i, 'datapath']]
        }
        output$showphotos1 <- renderImage({list(src=lst[[1]], height="200")})
        output$showphotos2 <- renderImage({list(src=lst[[2]], height="200")})
        output$showphotos3 <- renderImage({list(src=lst[[3]], height="200")})
        
        
        images_resized <- NULL
        for (i in 1:length(lst)) {
            
           image_scale(image = image_read(lst[[i]]), '200') %>% 
           image_write(path = str_c('image', i, '.png'), format = "png")
            
        }
        
        #image1.png ... image3.png are available in the working directory.
        
        #        drive_upload(image1, 
        #               as_id("https://drive.google.com/drive/u/1/folders/1qj0eeee...")

        
        })
}

shinyApp(ui, server)

Edit:
Adjust ui based on the number of images uploaded by the user.

library(shiny)
library(magick)
library(tidyverse)
library(googledrive)

ui <- fluidPage(
    fileInput("loadphotos", label = "Carregar fotos", multiple = TRUE),
    actionButton("do", "Carregar"),
    uiOutput('images_outputs')
)

server <- function(input, output, session) {
    
    observeEvent(input$do, {
        
        lst <- NULL
        for (i in 1:length(input$loadphotos[,1])) {
            lst[[i]] <- input$loadphotos[[i, 'datapath']]
        }
        
        output$images_outputs <- renderUI({
            tagList(
                map(str_c('showphotos', 1:length(lst)), ~imageOutput(.x, height = '200px')))
        })
        
        lst %>%
            map2(str_c('showphotos', 1:length(.)),~ { output[[.y]] <- renderImage({list(src = .x, height="200")},deleteFile = FALSE) })
        
        #a list with all the images but resized to 200
        #"x200" to resize by height
        images_resized <- lst %>% 
            map(~image_scale(image = image_read(.x), "200"))
        
        #images will be located in the project directory or home folder (getwd() to get working directory if in doubt)
        images_resized %>%
            walk2(str_c('image', 1:length(.)), ~ image_write(.x, path = str_c(.y, '.png'), format = "png"))
        
        
        #        drive_upload(image1.png, 
        #               as_id("https://drive.google.com/drive/u/1/folders/1qj0eeee...")
        
    })
    
}

shinyApp(ui, server)

note: It may be needed to adjust the maximum file size accepted by shiny using options(shiny.maxRequestSize={size}) as shown here

R shiny fileInput large files

Here is an example of using file.choose() in a shiny app to obtain the local path of the file (and hence the file name):

library(shiny)


ui <- fluidPage(

   # Application title
   titlePanel("Choosing a file example"),


   sidebarLayout(
      sidebarPanel(
        actionButton("filechoose",label = "Pick a file")
      ),

      mainPanel(
         textOutput("filechosen")
      )
   )
)


server <- function(input, output) {

  path <- reactiveValues(
    pth=NULL
  )


  observeEvent(input$filechoose,{
    path$pth <- file.choose()
  })

   output$filechosen <- renderText({

      if(is.null(path$pth)){
        "Nothing selected"
      }else{
        path$pth
      }
   })
}

# Run the application 
shinyApp(ui = ui, server = server)

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