att/rcloud.flexdashboard

flexdashboard from an RCloud notebook

Install

1. Install the rcloud.rmd package and this package on RCloud, using devtools::install_github() or install-github.me:

   source("https://install-github.me/att/rcloud.rmd")
   source("https://install-github.me/att/rcloud.flexdashboard")

2. In the RCloud Settings menu, in the Enable Extensions line, add rcloud.flexdashboard, so that the package is loaded automatically.
3. Reload RCloud in the browser. This loads the package, and you should have the flexdashboard.html item in the special pages menu, right beside the RCloud logo in the top left corner

Usage

R Markdown code chunks correspond to R notebook cells, and R Markdown text corresponds to markdown notebook cells.

To show the dashboard, select the flexdashboard.html special page, and then open it. rcloud.flexdashboard writes out an R Markdown file, calls rmarkdown::render on it, and then sends the outputted standalone HTML, embedded into an iframe to the browser.

Developer notes

The package uses rcloud.rmd to export the notebook to R Markdown.

The only tricky part of the implementation is loading the rcloud.flexdashboard package when in the dashboard. The call_notebook OCAP could be used to evaluate the notebook, but this would require that the user loads the rcloud.flexdashboard package manually in the notebook, and also that the user calls a special function in the last cell to transfer the formatted notebook to the browser. This is a solution that is used in the rcloud.rcap package.

Instead of this, we use a trick to trigger the loading of the package from JS. For this we call rcloud._ocaps.load_module_package() which loads the package as a side effect. We also need to define

.rcloud.export.ocaps <- function() { list() }

in the R package to avoid an error, because load_module_package() evaluates this.

When the package loads, we set up an OCAP in .onLoad(), and also assign it to window.RCloudFlexDashboard, so that we can call it from JS:

rcloud._ocaps.load_module_package(
    "rcloud.flexdashboard",
    function(x) {
        window.RCloudFlexDashboard.renderFlexDashboard(
            notebook,
            version,
            function(x) { console.log(x); }
        );
    }
);

The OCAP that we call simply saves the notebook to an R Markdown file (without actually evaluating it), and then calls rmarkdown::render() on it to create a standalone HTML file, which is then transmitted to the browser.

While this implementation works for authenticated users, it does not currently work for anonymous users, and it might be rewritten completely, see e.g. #13