Building Multi-Page {shiny} apps with {brochure}

NHS-R / 2022-02-16

Transcript

1. BUILDING MULTI-PAGE {SHINY} APPS WITH
   {BROCHURE}
   NHS-R / 2022-02-16
   COLIN FAY
   

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2. > whoami
   Colin FAY - Data Science Engineering & R-Hacker at
   ThinkR.
   Hyperactive open source developer, lead developer of
   the {golem} project, author of the Engineering
   Production Grade Shiny Apps book.
   https://rtask.thinkr.fr
   https://twitter.com/_colinfay
   https://github.com/colinfay
   https://colinfay.me
   Colin FAY (@_ColinFay) - https://rtask.thinkr.fr 2 / 23
   

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3. Data Science
   engineering, focused on
   R
    Training
    Software Engineering
    R in production
    Consulting
   Colin FAY (@_ColinFay) - https://rtask.thinkr.fr 3 / 23
   

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4. BUILDING MULTI-PAGE {SHINY} APPS WITH
   {BROCHURE}
   

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5. Multiple Page Shiny Apps with
   {brochure}
   Colin FAY (@_ColinFay) - https://rtask.thinkr.fr 5 / 23
   

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6. I know what you're thinking
   🤔
   Colin FAY (@_ColinFay) - https://rtask.thinkr.fr 6 / 23
   

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7. YASE (Yet Another Shiny
   Extension)
   Colin FAY (@_ColinFay) - https://rtask.thinkr.fr 7 / 23
   

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8. Ok let me explain
   🗣
   Colin FAY (@_ColinFay) - https://rtask.thinkr.fr 8 / 23
   

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9. (Because yes, there's a rational
   explaination)
   Colin FAY (@_ColinFay) - https://rtask.thinkr.fr 9 / 23
   

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10. 10(*) types of webapps
    Multi-page apps
    The "traditionnal" way of building content on the web.
    Each time you move from one page to another, the whole content is reloaded.
    This is how most websites work.
    Single page apps
    More "modern" way to build apps.
    The HTML/CSS/JS is uploaded one time, and its content is updated via JavaScript requests
    to the server.
    This is how {shiny} works.
    (*) Sorry for everyone not getting the joke, I just read a book about binary numbers and wanted to
    sound smart.
    Colin FAY (@_ColinFay) - https://rtask.thinkr.fr 10 / 23
    

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11. What's wrong with the way
    {shiny} works?
    Nothing, but let's take a step back
    What do I need when I build a web app?
    Colin FAY (@_ColinFay) - https://rtask.thinkr.fr 11 / 23
    

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12. What do I need when building a
    web app ?
     Multiple paths (real ones): /, /analysis, /results, /contact...
     Not load the whole app everytime
     Cookies
     Healtcheck
     HTTP method support (POST, PUT, DELETE, etc.)
     HTTP code support (200, 300, 400...)
     Tweak http requests and responses
    And many others things
    Colin FAY (@_ColinFay) - https://rtask.thinkr.fr 12 / 23
    

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13. But why would I want that?
    Serving static, pure HTML landing pages
    Being able to point to specific part of the app (not 'open the app, click there and there
    and see')
    Lower the load on the server by serving static HTML elements
    Monitor your app via healthcheck
    Identify the user when they come back to the app
    POST elements to the server
    Add a 404 page for unreachable pages
    Redirect pages to others
    Colin FAY (@_ColinFay) - https://rtask.thinkr.fr 13 / 23
    

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14. HERE COMES {BROCHURE}!
    

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15. Previous works
    {blaze} https://github.com/nteetor/blaze
    {shiny.router} https://github.com/Appsilon/shiny.router
    => Not really multi-page, but "hack" your browser path by using URL fragments
    A Fragment URL Specifies A Location Within A Page
    Url fragments create history in your browser but don't reload the full page
    Are not sent as part of the http request (so it can be harder to log what's happening in
    the app)
    => Don't have all the features from the last slide
    Colin FAY (@_ColinFay) - https://rtask.thinkr.fr 15 / 23
    

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16. Basic brochure
    library(shiny)
    
    library(brochure)
    
    brochureApp(
    
    page(
    
    href = "/",
    
    ui = fluidPage(
    
    plotOutput("plot")
    
    ),
    
    server = function(input, output, session) {
    
    output$plot <- renderPlot({
    
    plot(iris)
    
    })
    
    }
    
    ),
    
    page(
    
    href = "/page2",
    
    ui = fluidPage(
    
    h1("This is my second page")
    
    )
    
    )
    
    )
    Colin FAY (@_ColinFay) - https://rtask.thinkr.fr 16 / 23
    

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17. About HTTP
    

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18. log_where <- function(req) {
    
    cli::cat_rule(
    
    sprintf(
    
    "%s - %s",
    
    Sys.time(),
    
    req$PATH_INFO
    
    )
    
    )
    
    req
    
    }
    
    brochureApp(
    
    req_handlers = list(
    
    log_where
    
    )
    
    )
    Cookies, request and response
    handlers
    Colin FAY (@_ColinFay) - https://rtask.thinkr.fr 18 / 23
    

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19. Cookies, request and response
    handlers
    login <- function() {
    
    page(
    
    href = "/login",
    
    ui = tagList(
    
    h1("You've just logged!")
    
    ),
    
    server = function(input, output, session) {
    
    },
    
    res_handlers = list(
    
    ~ set_cookie(.x, "BROCHURECOOKIE", 12)
    
    )
    
    )
    
    }
    Colin FAY (@_ColinFay) - https://rtask.thinkr.fr 19 / 23
    

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20. brochureApp(
    
    # Pages
    
    page_1(),
    
    page_2(),
    
    page_contact(),
    
    page(
    
    href = "/check",
    
    ui = tagList(),
    
    # This req_handler will returns
    
    # an httpResponse, it will be
    
    # returned directly to the browser
    
    req_handlers = list(
    
    # Exported since shiny 1.6.0
    
    ~ shiny::httpResponse(
    
    200,
    
    content = "OK"
    
    )
    
    )
    
    )
    
    )
    > httr::GET('http://url/check')
    Response [http://url/check]
    Date: 2022-02-16 12:19
    Status: 200
    Content-Type: text/html;
    charset=UTF-8
    Size: 2 B
    Simple healthcheck
    Colin FAY (@_ColinFay) - https://rtask.thinkr.fr 20 / 23
    

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21. Demo time
    Colin FAY (@_ColinFay) - https://rtask.thinkr.fr 21 / 23
    

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22. 📖 engineering-shiny.org/
    Colin FAY (@_ColinFay) - https://rtask.thinkr.fr 22 / 23
    

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23. Thx! Questions?
    Find me Online
    colin@thinkr.fr
    https://twitter.com/_colinfay
    https://twitter.com/thinkr_fr
    https://github.com/ColinFay
    https://thinkr.fr/
    https://rtask.thinkr.fr/
    https://colinfay.me/
    Colin FAY (@_ColinFay) - https://rtask.thinkr.fr 23 / 23
    

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