https://github.com/ixpantia/tower

Ergonomic middleware for Shiny applications
https://github.com/ixpantia/tower

Last synced: 8 days ago
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Ergonomic middleware for Shiny applications

• Host: GitHub
• URL: https://github.com/ixpantia/tower
• Owner: ixpantia
• License: other
• Created: 2024-01-31T02:58:12.000Z (11 months ago)
• Default Branch: main
• Last Pushed: 2024-10-22T02:07:49.000Z (about 2 months ago)
• Last Synced: 2024-11-06T09:09:17.418Z (about 1 month ago)
• Language: R
• Homepage: https://ixpantia.github.io/tower/
• Size: 4.51 MB
• Stars: 16
• Watchers: 2
• Forks: 1
• Open Issues: 2
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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• jimsghstars - ixpantia/tower - Ergonomic middleware for Shiny applications (R)

README

        
# tower

[![R-CMD-check](https://github.com/ixpantia/tower/actions/workflows/R-CMD-check.yaml/badge.svg)](https://github.com/ixpantia/tower/actions/workflows/R-CMD-check.yaml)

Dead simple middleware for R Shiny.

## Summary

`tower` is a simple library for adding middleware to Shiny applications.

It is inspired by the [tower](https://docs.rs/tower/latest/tower/) crate for Rust.

It is designed to enable package authors and Shiny developers to extend

Shiny a little bit more than what is usually possible.

You can use  `tower` to add middlewares that forward, modify, or intercept

requests in Shiny applications. This can be useful for adding logging, authentication,

caching, or routing to your Shiny applications.

## Installation

You can install the development version of `tower` from GitHub with:

``` r

# install.packages("remotes")

remotes::install_github("ixpantia/tower")

```

## Example

We may want to add a new route to our Shiny application that adds a count

to a counter every time a user visits the route. We can do this with `tower`

by adding a middleware that intercepts the request and increments the counter.

``` r

library(shiny)

library(tower)

# Counter environment

global_counter <- new.env()

global_counter$count <- 0

# Middleware to increment the counter

increment_counter <- function(req) {

  global_counter$count <- global_counter$count + 1

  response_builder() |>

    add_body(paste("Counter is now", global_counter$count)) |>

    build_response()

}

# A very empty Shiny app (not necesarry for the demo)

ui <- fluidPage()

server <- function(input, output, session) {}

shinyApp(ui, server) |>

  create_tower() |>

  add_get_route("/counter", increment_counter) |>

  build_tower()

```

If you run the code above and visit the route `/counter` in your browser,

you will see the counter increment every time you visit the route.

## How it works

Basically, `tower` adds layers to a Shiny application. A layer is a function

that takes a request and returns either a response or NULL. If a layer returns

a response, the response is sent to the client and the request is not forwarded

to the next layer. If a layer returns NULL, the request is forwarded to the next

layer.