Shiny app: Can't plot stock chart based on user input - r

Question

I am trying to plot a stock chart using quantmod in a shiny app but I get the following error: input$stockInput download failed after two attempts. Error message: HTTP error 404. Any help is appreciated.
Server:
library(quantmod)
shinyServer(function(input, output) {
output$distPlot <- renderPlot({
price <- getSymbols('input$stockInput',from='2017-01-01')
plot(price)
})})
UI:
library(shiny)
shinyUI(fluidPage(
titlePanel("Stock Chart"),
sidebarLayout(
sidebarPanel(
#This is a dropdown to select the stock
selectInput("stockInput",
"Pick your stock:",
c("AMZN","FB","GOOG","NVDA","AAPL"),
"AMZN"),selected = "GOOG"),
# Show a plot of the generated distribution
mainPanel(
plotOutput("distPlot")
))))
Thank you.

Answer 1

Your code requires a few changes. First when you are accessing a shiny UI object in server.R you should use it as an object not as a quoted character
price <- getSymbols(input$stockInput,from='2017-01-01')
And the function getSymbols without a value set to the argument (auto.assign = F) creates a new xts object in the stock name whose data is requested and so in the below code I've used it with setting auto.assign = F so it becomes easier to access the object price for plotting. Otherwise, you might have to fetch the value inside price using get() and then plot them as I've commented.
server.R
library(quantmod)
shinyServer(function(input, output) {
output$distPlot <- renderPlot({
price <- getSymbols(input$stockInput,from='2017-01-01', auto.assign = F)
#plot(get(price), main = price) #this is used when auto.assign is not set by default which is TRUE
plot(price, main = input$stockInput) # this is when the xts object is stored in the name price itself
})})
ui.R
library(shiny)
shinyUI(fluidPage(
titlePanel("Stock Chart"),
sidebarLayout(
sidebarPanel(
#This is a dropdown to select the stock
selectInput("stockInput",
"Pick your stock:",
c("AMZN","FB","GOOG","NVDA","AAPL"),
"AMZN"),selected = "GOOG"),
# Show a plot of the generated distribution
mainPanel(
plotOutput("distPlot")
))))
Hope it clarifies!