How to link rmarkdown report with shinyapps to export webapp content in R?

Question

I am trying to build a webapp with shiny in R which shows values of different indicators by means of a couple of tables, one dynamic graph and one image. The result is like a factsheet for a selected item from a list and I’d like to capture the results and provide the possibility to download what is shown in the screen (the tables, graph and image).

I saw I could do it by generating a report in Rmarkdown and export it with downloadHandler, following this example (http://dev.use-r.com/shiny-examples/016-knitr-pdf). As far as I understand, in the server the output$downloadReport creates the object composed by the filename and the content based on a template of the report previously stored in the same directory as ui.R and server.R according to this:

 #Output report
 output$downloadReport <- downloadHandler(
  filename = function() {
   paste(input$City_id,'factsheet', sep = '.', switch(
    input$format, PDF = 'pdf', HTML = 'html', Word = 'docx'
  ))
 },

  content = function(file) {
   src <- normalizePath('report.Rmd')
   return(src)

   # temporarily switch to the temp dir, in case you do not have write
   # permission to the current working directory
   owd <- setwd(tempdir())
   on.exit(setwd(owd))
   file.copy(src, 'report.Rmd')

   library(rmarkdown)
   out <- render('report.Rmd', switch(
     input$format,
     PDF = pdf_document(), HTML = html_document(), Word = word_document()
   ))
   file.rename(out, file)
  }
 )

To check the template for the report in this example I followed this (https://github.com/rstudio/shiny-examples/blob/master/016-knitr-pdf/report.Rmd). But,when I want to create my ‘report.Rmd’ template, I see there are different ways to create a new R markdown document (document with different output formats, presentation, shiny, and template), and this selection influences the output. I have tried some of them but didn’t succeed to make it work.

For instance, I took a new R Markdown document html output format, named ‘report.Rmd’ and saved in the same folder as ui and server files. With some very simple content:

title: "Untitled"
author: "Raquel_ub"
date: "Tuesday, October 27, 2015"
output: html_document
---

# Selected city
```{r, echo=FALSE}
level(input$City_id)
```

I get this non-informative error: Error opening file: 2 Error reading: 6

Any hint/clue on what’s going on is more than welcome!

Many thanks, Raquel

Ah, my session info:

> sessionInfo()
R version 3.1.1 (2014-07-10)
Platform: x86_64-w64-mingw32/x64 (64-bit)

locale:
[1] LC_COLLATE=Spanish_Spain.1252  LC_CTYPE=Spanish_Spain.1252   
[3] LC_MONETARY=Spanish_Spain.1252 LC_NUMERIC=C                  
[5] LC_TIME=Spanish_Spain.1252    

attached base packages:
[1] splines   stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] rmarkdown_0.8.1   shiny_0.12.2      rsconnect_0.4.1.7 rCharts_0.4.5    
[5] doBy_4.5-13       survival_2.37-7   foreign_0.8-66   

loaded via a namespace (and not attached):
 [1] digest_0.6.8     evaluate_0.8     formatR_1.2.1    grid_3.1.1      
 [5] htmltools_0.2.6  httpuv_1.3.3     jsonlite_0.9.17  knitr_1.11      
 [9] lattice_0.20-29  magrittr_1.5     MASS_7.3-33      Matrix_1.1-4    
[13] mime_0.4         packrat_0.4.5    plyr_1.8.3       R6_2.1.1        
[17] Rcpp_0.12.1      RJSONIO_1.3-0    rstudio_0.98.977 rstudioapi_0.3.1
[21] stringi_1.0-1    stringr_1.0.0    tools_3.1.1      whisker_0.3-2   
[25] xtable_1.7-4     yaml_2.1.13   

Answer 1

I faced a similar situation and also tried downloadHandler but I couldn't make it work so what I did was:

1. In the server codeblock, put your resulting plots, data.frames, etc. in the global Environment like this: plot1<<-ggplot().
2. save these objects with save("df.1","plot1", file="path/to/file/MyData.RData").
3. Load MyData.RData file in a template.Rmd file:

```{r, echo=FALSE, message=FALSE} load("path/to/file/myData.RData") ```

I think the rest is pretty easy to figure out.

Cheers!