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Reference app for conditional UI and links
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Reference app for conditional UI and links |
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#library(shiny) | |
# Functions --------------------------------------------------------------- | |
createRecord <- function(input, db) { | |
db$data <- rbind( | |
db$data, | |
data.frame( | |
firstname = input$firstname, | |
lastname =input$lastname, | |
stringsAsFactors = FALSE | |
) | |
) | |
} | |
updateRecord <- function(input, db, selection) { | |
db$data[selection, ] <- data.frame( | |
firstname = input$firstname, | |
lastname =input$lastname, | |
stringsAsFactors = FALSE | |
) | |
} | |
deleteRecord <- function(db, selection) { | |
db$data <- db$data[-selection, ] | |
} |
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# Server ------------------------------------------------------------------ | |
server <- function(input, output, session) { | |
## Initialize DB // | |
db <- reactiveValues(data = data.frame(title = NA, description = NA)[-1,]) | |
## UI control // | |
ui_control <- reactiveValues( | |
case = c("hide", "create", "update")[1], | |
selection = NULL, | |
render_table = TRUE | |
) | |
## Observe // | |
observeEvent(input$action_trigger, { | |
ui_control$case <- "create" | |
}) | |
observeEvent(input$action_create, { | |
createRecord(input, db = db) | |
ui_control$case <- "hide" | |
}) | |
observeEvent(input$action_update, { | |
updateRecord(input, db = db, selection = ui_control$selection) | |
ui_control$case <- "hide" | |
}) | |
observeEvent(input$action_delete, { | |
deleteRecord(db = db, selection = ui_control$selection) | |
ui_control$case <- "hide" | |
}) | |
observeEvent(input$action_cancel, { | |
ui_control$case <- "hide" | |
}) | |
## Reset input fields: | |
observe({ | |
if (ui_control$case == "create") { | |
updateTextInput(session, "title", value = "") | |
updateTextInput(session, "description", value = "") | |
} | |
}) | |
observe({ | |
idx <- input$datatable_rows_selected | |
if (!is.null(idx)) { | |
ui_control$case <- "update" | |
} else { | |
ui_control$case <- "hide" | |
} | |
ui_control$selection <- idx | |
}) | |
## Render UI // | |
output$ui_input <- renderUI({ | |
case <- ui_control$case | |
if (case == "hide") return() | |
## Case dependent input // | |
if (case == "create") { | |
# title <- "" | |
title <- ifelse(is.null(tmp <- isolate(input$title)), "", tmp) | |
# description <- "" | |
description <- ifelse(is.null(tmp <- isolate(input$description)), "", tmp) | |
## NOTE Simply case-based assignment of `""` was my first approach to | |
## resetting input values, but I think doing it via a combination of | |
## `observe()` and `updateTextInput()` is more straightforward and | |
## decoupled. Why the `isolate()`? --> otherwise I take a direct | |
## dependency on every change of the input fields | |
buttons <- div(style="display:inline-block", | |
actionButton("action_create", "Create"), | |
actionButton("action_cancel", "Cancel") | |
) | |
updateTextInput(session, "first") | |
} else if (case == "update") { | |
title <- db$data[ui_control$selection, "title"] | |
description <- db$data[ui_control$selection, "description"] | |
buttons <- div(style="display:inline-block", | |
actionButton("action_update", "Update"), | |
actionButton("action_cancel", "Cancel"), | |
p(), | |
actionButton("action_delete", "Delete", | |
icon = icon("exclamation-triangle")) | |
) | |
} else { | |
stop(sprintf("Invalid case: %s", case)) | |
} | |
tagList( | |
textInput("title", "Title", title), | |
textInput("description", "Description", description), | |
buttons | |
) | |
}) | |
## Database // | |
output$datatable <- DT::renderDataTable( | |
db$data, server = FALSE, selection = list(target = "row+column") | |
) | |
## Observe action links // | |
observeEvent(input$link_to_tab_b, { | |
newvalue <- "B" | |
updateTabsetPanel(session, "tabs", newvalue) | |
}) | |
observeEvent(input$link_to_tab_a, { | |
newvalue <- "A" | |
updateTabsetPanel(session, "tabs", newvalue) | |
}) | |
} |
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# UI --------------------------------------------------------------------- | |
ui <- fluidPage( | |
tabsetPanel( | |
id = "tabs", | |
tabPanel( | |
"A", | |
p(), | |
actionButton("action_trigger", "Create"), | |
h3("Database state"), | |
DT::dataTableOutput("datatable"), | |
p(), | |
uiOutput("ui_input"), | |
p(), | |
actionLink("link_to_tab_b", "Action link example: go to tab B") | |
), | |
tabPanel( | |
"B", | |
p(), | |
actionLink("link_to_tab_a", "Action link example: go to tab A") | |
) | |
) | |
) |
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