1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
|
# Creates an object whose $ and [[ pass through to the parent
# session, unless the name is matched in ..., in which case
# that value is returned instead. (See Decorator pattern.)
createSessionProxy <- function(parentSession, ...) {
e <- new.env(parent = emptyenv())
e$parent <- parentSession
e$overrides <- list(...)
structure(
e,
class = "session_proxy"
)
}
#' @export
`$.session_proxy` <- function(x, name) {
if (name %in% names(.subset2(x, "overrides")))
.subset2(x, "overrides")[[name]]
else
.subset2(x, "parent")[[name]]
}
#' @export
`[[.session_proxy` <- `$.session_proxy`
#' @export
`$<-.session_proxy` <- function(x, name, value) {
# this line allows users to write into session$userData
# (e.g. it allows something like `session$userData$x <- TRUE`,
# but not `session$userData <- TRUE`) from within a module
# without any hacks (see PR #1732)
if (identical(x[[name]], value)) return(x)
stop("Attempted to assign value on session proxy.")
}
`[[<-.session_proxy` <- `$<-.session_proxy`
#' Shiny modules
#'
#' Shiny's module feature lets you break complicated UI and server logic into
#' smaller, self-contained pieces. Compared to large monolithic Shiny apps,
#' modules are easier to reuse and easier to reason about. See the article at
#' <http://shiny.rstudio.com/articles/modules.html> to learn more.
#'
#' Starting in Shiny 1.5.0, we recommend using `moduleServer` instead of
#' [`callModule()`], because the syntax is a little easier
#' to understand, and modules created with `moduleServer` can be tested with
#' [`testServer()`].
#'
#' @param module A Shiny module server function.
#' @param id An ID string that corresponds with the ID used to call the module's
#' UI function.
#' @param session Session from which to make a child scope (the default should
#' almost always be used).
#'
#' @return The return value, if any, from executing the module server function
#' @seealso <http://shiny.rstudio.com/articles/modules.html>
#'
#' @examples
#' # Define the UI for a module
#' counterUI <- function(id, label = "Counter") {
#' ns <- NS(id)
#' tagList(
#' actionButton(ns("button"), label = label),
#' verbatimTextOutput(ns("out"))
#' )
#' }
#'
#' # Define the server logic for a module
#' counterServer <- function(id) {
#' moduleServer(
#' id,
#' function(input, output, session) {
#' count <- reactiveVal(0)
#' observeEvent(input$button, {
#' count(count() + 1)
#' })
#' output$out <- renderText({
#' count()
#' })
#' count
#' }
#' )
#' }
#'
#' # Use the module in an app
#' ui <- fluidPage(
#' counterUI("counter1", "Counter #1"),
#' counterUI("counter2", "Counter #2")
#' )
#' server <- function(input, output, session) {
#' counterServer("counter1")
#' counterServer("counter2")
#' }
#' if (interactive()) {
#' shinyApp(ui, server)
#' }
#'
#'
#'
#' # If you want to pass extra parameters to the module's server logic, you can
#' # add them to your function. In this case `prefix` is text that will be
#' # printed before the count.
#' counterServer2 <- function(id, prefix = NULL) {
#' moduleServer(
#' id,
#' function(input, output, session) {
#' count <- reactiveVal(0)
#' observeEvent(input$button, {
#' count(count() + 1)
#' })
#' output$out <- renderText({
#' paste0(prefix, count())
#' })
#' count
#' }
#' )
#' }
#'
#' ui <- fluidPage(
#' counterUI("counter", "Counter"),
#' )
#' server <- function(input, output, session) {
#' counterServer2("counter", "The current count is: ")
#' }
#' if (interactive()) {
#' shinyApp(ui, server)
#' }
#'
#' @export
moduleServer <- function(id, module, session = getDefaultReactiveDomain()) {
if (inherits(session, "MockShinySession")) {
body(module) <- rlang::expr({
session$setEnv(base::environment())
!!body(module)
})
session$setReturned(callModule(module, id, session = session))
} else {
callModule(module, id, session = session)
}
}
#' Invoke a Shiny module
#'
#' Note: As of Shiny 1.5.0, we recommend using [`moduleServer()`] instead of
#' [`callModule()`], because the syntax is a little easier
#' to understand, and modules created with `moduleServer` can be tested with
#' [`testServer()`].
#'
#' @param module A Shiny module server function
#' @param id An ID string that corresponds with the ID used to call the module's
#' UI function
#' @param ... Additional parameters to pass to module server function
#' @param session Session from which to make a child scope (the default should
#' almost always be used)
#'
#' @return The return value, if any, from executing the module server function
#' @export
callModule <- function(module, id, ..., session = getDefaultReactiveDomain()) {
if (!inherits(session, c("ShinySession", "session_proxy", "MockShinySession"))) {
stop("session must be a ShinySession or session_proxy object.")
}
childScope <- session$makeScope(id)
withReactiveDomain(childScope, {
if (!is.function(module)) {
stop("module argument must be a function")
}
module(childScope$input, childScope$output, childScope, ...)
})
}
|
