R Shiny How to use renderPlot to build barplot while retrieving data from mysqlDB based on user selection

Question

I have a dataset in DB, and based on user selection, I'd like to build a bar plot using render plot in r shiny. I was able to get the data and display it as a table using renderTable, but I was not able to create renderPlot. I'm also trying to get the data from server to UI in the form of dataframe, currently, I'm getting it as dataTable.

P.S: This is my first time learning R Shiny. Just trying to understand the dynamics of this language.

Here is my code.

library(DT)
library(shiny)
library(DBI)

# the user interface

ui <- fluidPage(

    titlePanel(strong ("Welcome to User Details")),
    sidebarPanel(

        selectInput("selectedName", label = h5("Select the User name here"),
                    choices = list("A", "B", "C", "D"),
                    selected = "A"),
        submitButton("Submit")
       
),
mainPanel(
    is.data.frame("data"),
    tableOutput("data")
 
)
)

# server
server <- function(input, output){
   
    output$data <- renderTable({
        conn <- dbConnect(
            drv = RMySQL::MySQL(),
            dbname = "mydb",
            host = "localhost",
            port = 3306,
            username = "root",
            password = "pwd")
        on.exit(dbDisconnect(conn), add = TRUE)
        dbGetQuery(conn, paste0(
            "Select name, age, gender from table1 Where userShortName = '", intput$selectedName, "';")
    })
}

# app launch
shinyApp(ui = ui, server = server)

And output will create a False (for dataframe) and create a Table with these 3 column names name, age, gender.

I'm trying to plot a simple bar plot based on name and age by grouping the genders. name on X-Axis, Age on Y-Axis, and all females grouped, all males grouped together.

Update:

Trying with renderplot instead of renderTable

    library(DT)
    library(shiny)
    library(DBI)
    
    ui <- fluidPage(

    titlePanel(strong ("Welcome to User Details")),
    sidebarPanel(

        selectInput("selectedName", label = h5("Select the User name here"),
                    choices = list("A", "B", "C", "D"),
                    selected = "A"),
        submitButton("Submit")

),
    mainPanel(
        textOutput("sample_name"),
        plotOutput(outputId = "protein_data")
    ))
    
    # server
    server <- function(input, output){
       
        conn <- dbConnect(
            drv = RMySQL::MySQL(),
            dbname = "mydb",
            host = "localhost",
            port = 3306,
            username = "root",
            password = "pwd")
       
        output$data <- renderPlot({
           
           
            table <- dbGetQuery(conn, statement = "Select name, age, gender from table1 Where userShortName = '", intput$selectedName, "';")
           
            df <- as.data.frame(unclass(table(table$name,
                                               table$age)))
            
            barplot(x=table$name, y=table$age)
        })
    }
    
    # app launch
    shinyApp(ui = ui, server = server)

This code gives me the following error: Error: need finit xlim values shiny.

Answer 1

Storing your query in a table and converting that table into dataframe. Use renderplotly and plotly method to plot barchart.

library(DT)
library(shiny)
library(DBI)
library(plotly) # use plotly library here

# the user interface

ui <- fluidPage(

    titlePanel(strong ("Welcome to User Details")),
    sidebarPanel(

        selectInput("selectedName", label = h5("Select the User name here"),
                    choices = list("A", "B", "C", "D"),
                    selected = "A"),
        submitButton("Submit")       
),
mainPanel(
    is.data.frame("data"),
    tableOutput("data")
 
)
)

server

server <- function(input, output){
   
    output$data <- renderPlotly({

        conn <- dbConnect(
            drv = RMySQL::MySQL(),
            dbname = "mydb",
            host = "localhost",
            port = 3306,
            username = "root",
            password = "pwd")
        on.exit(dbDisconnect(conn), add = TRUE)
        table <- dbGetQuery(conn, paste0(
            "Select name, age, gender from table1 Where userShortName = '", input$selectedName, "';")
         
        # converting table into dataframes, easy to plot
        table1 <- as.data.frame(table)

        # Barplot using plotly
        plot_ly(data=table1,x=~name, y=~age, type="bar")%>%
            layout(
                title = "Title of Barplot",
                xaxis = list(title="Name"),
                yaxis = list(title="Age")
            )
    })
}

# app launch
shinyApp(ui = ui, server = server)

Answer 2

First you need to render your chart to output$protein_data not to output$data as it doesn't exist anymore on your second script.

Then change the barplot arguments to barplot(age~name, data = df)

library(DT)
library(shiny)
library(DBI)

ui <- fluidPage(
  
  titlePanel(strong ("Welcome to User Details")),
  sidebarPanel(
    
    selectInput("selectedName", label = h5("Select the User name here"),
                choices = list("A", "B", "C", "D"),
                selected = "A"),
    submitButton("Submit")
    
  ),
  mainPanel(
    textOutput("sample_name"),
    plotOutput(outputId = "protein_data")
  ))

# server
server <- function(input, output){
  
  conn <- dbConnect(
    drv = RMySQL::MySQL(),
    dbname = "mydb",
    host = "localhost",
    port = 3306,
    username = "root",
    password = "pwd")
  
  output$protein_data <- renderPlot({
    
    
    table <- dbGetQuery(conn, statement = "Select name, age, gender from table1 Where userShortName = '", intput$selectedName, "';")
    
    df <- as.data.frame(unclass(table(table$name,
                                      table$age)))
    
    barplot(age~name, data = df)
  })
}

# app launch
shinyApp(ui = ui, server = server)