how to integerate R script in Shiny web page?

Question

In R script, I built a svm model by provide training. and in shiny webpage i designed user interface in which one textbox and two textarea are placed to get input from user.

Now i want that when user submit on button the textbox and textarea value should be used by R script program in which a training is given to model and now new input is used to classify data by built in model.

so how to pass text field value of shiny webpage to R script?

 ui <- fluidPage( fluidRow(id="form-row",column(6,offset =3 ,id="form-col",p(id="mandatory","'*' Fields are manadatory"),div(id = "form",
                              div(id="p-container",p(id="form-header","Your Question")), 
                              div(id="form-field-container",
                              textInput("title", "*Title",  width='100%',placeholder="Your Title is here..."),
                             # verbatimTextOutput("value"),
                            textOutput("title_val"),
                            #for text area width 100%
                              tags$style(HTML(".shiny-input-container:not(.shiny-input-container-inline){width: 100%;}")),
                              textAreaInput("description", "*Description", width='100%',rows = 3, resize = "both",placeholder="Description..."),
                            textOutput("desc_val"),  
                            textAreaInput("code", "*Code", width='100%',rows = 3, resize = "both",placeholder="Write your code..."),
                            textOutput("code_val"),
                            useShinyalert(),
                              actionButton("submit", "Submit", class = "btn-primary")
                              ))
        )
    )
)
server <- function(input, output, session){
  observeEvent( input$submit,{
    title_val <- as.character(input$title)
    desc_val <- as.character(input$description)
    code_val <- as.character(input$code)
    ques<- paste(desc_val, code_val,sep=" \n")
  shinyalert( title_val, ques, type = "success")

  })
}

shinyApp(ui=ui, server=server)

Answer 1

You could do something like this:

eval(parse(text = input$code))

You could use eval and parse to evaluate a string.

library(shiny)
library(tidyverse)
library(shinyalert)

ui <- fluidPage( fluidRow(id="form-row",column(6,offset =3 ,id="form-col",p(id="mandatory","'*' Fields are manadatory"),div(id = "form",
                div(id="p-container",p(id="form-header","Your Question")), 
                div(id="form-field-container",
                textInput("title", "*Title",  width='100%',placeholder="Your Title is here..."),
                # verbatimTextOutput("value"),
                textOutput("title_val"),
                #for text area width 100%
                tags$style(HTML(".shiny-input-container:not(.shiny-input-container-inline){width: 100%;}")),
                textAreaInput("description", "*Description", width='100%',rows = 3, resize = "both",placeholder="Description..."),
                textOutput("desc_val"),  
                textAreaInput("code", "*Code", width='100%',rows = 3, resize = "both",placeholder="Write your code..."),
                textOutput("code_val"),
                useShinyalert(),
                actionButton("submit", "Submit", class = "btn-primary")
                ))
)
)
)



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

    model <- reactive({

        data <- mtcars # use your own data, might it be in a fileinput or some other data

        result <- eval(parse(text = input$code)) # Should include a hint to what way your dataframe is called and how it looks.
        result

    })


    observeEvent( input$submit,{
        title_val <- as.character(input$title)
        desc_val <- as.character(input$description)
        code_val <- as.character(input$code)
        ques<- paste(desc_val, code_val,sep=" \n")
        shinyalert( title_val, ques, type = "success")

    })
}

shinyApp(ui=ui, server=server)

But to be honest, I do not like the idea to parse and evaluate text from a userinput. Far too many possibilites to run into trouble.

The main advantage that someone who is not familiar with R is gone when I have to copy and paste a script as input