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Use session object instead of just clientData

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Winston Chang
2013-06-04 22:13:11 -05:00
parent 4d1b9ac755
commit a4a92b63ed
2 changed files with 26 additions and 24 deletions
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34
_includes/tutorial/client-data.md
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@@ -1,32 +1,32 @@
## Getting Non-Input Data From the Client
On the server side, Shiny applications use the `input` object to receive user input from the client web browser. The values in `input` are set by UI objects on the client web page. There are also non-input values (in the sense that the user doesn't enter these values through UI components) that are stored in an object called `clientData`. These values include the URL, the pixel ratio (for high-resolution "Retina" displays), the hidden state of output objects, and the height and width of plot outputs.
On the server side, Shiny applications use the `input` object to receive user input from the client web browser. The values in `input` are set by UI objects on the client web page. There are also non-input values (in the sense that the user doesn't enter these values through UI components) that are stored in an object called `session$clientData`. These values include the URL, the pixel ratio (for high-resolution "Retina" displays), the hidden state of output objects, and the height and width of plot outputs.
### Using clientData
### Using session$clientData
To access `clientData` values, you need to pass a function to `shinyServer()` that takes `clientData` as an argument. Once it's in there, you can access `clientData` just as you would `input`.
To access `session$clientData` values, you need to pass a function to `shinyServer()` that takes `session` as an argument (`session` is a special object that is used for finer control over a user's app session). Once it's in there, you can access `session$clientData` just as you would `input`.
In the example below, the client browser will display out the components of the URL and also parse and print the query/search string (the part of the URL after a "`?`"):
#### server.R
{% highlight r %}
shinyServer(function(input, output, clientData) {
shinyServer(function(input, output, session) {
# Return the components of the URL in a string:
output$urlText <- renderText({
paste(sep = "",
"protocol: ", clientData$url_protocol, "\n",
"hostname: ", clientData$url_hostname, "\n",
"pathname: ", clientData$url_pathname, "\n",
"port: ", clientData$url_port, "\n",
"search: ", clientData$url_search, "\n"
"protocol: ", session$clientData$url_protocol, "\n",
"hostname: ", session$clientData$url_hostname, "\n",
"pathname: ", session$clientData$url_pathname, "\n",
"port: ", session$clientData$url_port, "\n",
"search: ", session$clientData$url_search, "\n"
)
})
# Parse the GET query string
output$queryText <- renderText({
query <- parseQueryString(clientData$url_search)
query <- parseQueryString(session$clientData$url_search)
# Return a string with key-value pairs
paste(names(query), query, sep = "=", collapse=", ")
@@ -54,17 +54,19 @@ This app will display the following:
### Viewing all available values in clientData
The values in `clientData` will depend to some extent on the outputs. For example, a plot output object will report its height, width, and hidden status. The app below has a plot output, and displays all the values in `clientData`:
The values in `session$clientData` will depend to some extent on the outputs. For example, a plot output object will report its height, width, and hidden status. The app below has a plot output, and displays all the values in `session$clientData`:
{% highlight r %}
shinyServer(function(input, output, clientData) {
shinyServer(function(input, output, session) {
# Store in a convenience variable
cdata <- session$clientData
# Values from clientData returned as text
# Values from cdata returned as text
output$clientdataText <- renderText({
cnames <- names(clientData)
cnames <- names(cdata)
allvalues <- lapply(cnames, function(name) {
paste(name, clientData[[name]], sep=" = ")
paste(name, cdata[[name]], sep=" = ")
})
paste(allvalues, collapse = "\n")
})
@@ -76,7 +78,7 @@ shinyServer(function(input, output, clientData) {
})
{% endhighlight %}
Notice that, just as with `input`, values in `clientData` can be accessed with `clientData$myvar` or `clientData[['myvar']]`.
Notice that, just as with `input`, values in `session$clientData` can be accessed with `session$clientData$myvar` or `session$clientData[['myvar']]`. Or, equivalently, since we've saved it into a convenience variable `cdata`, we can use `cdata$myvar` or `cdata[['myvar']]`.
##### ui.R

16
_includes/tutorial/sending-images.md
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@@ -38,7 +38,7 @@ Image files can be sent using `renderImage()`. The expression that you pass to `
#### server.R
{% highlight r %}
shinyServer(function(input, output, clientData) {
shinyServer(function(input, output, session) {
output$myImage <- renderImage({
# A temp file to save the output.
# This file will be removed later by renderImage
@@ -114,7 +114,7 @@ If your Shiny app has pre-rendered images saved in a subdirectory, you can send
#### server.R
{% highlight r %}
shinyServer(function(input, output, clientData) {
shinyServer(function(input, output, session) {
# Send a pre-rendered image, and don't delete the image after sending it
output$preImage <- renderImage({
# When input$n is 3, filename is ./images/image3.jpeg
@@ -136,24 +136,24 @@ Note that this might be less efficient than putting images in `www/images` and e
### Using clientData values
In the first example above, the plot size was fixed at 400 by 300 pixels. For dynamic resizing, it's possible to use values from `clientData` to detect the output size.
In the first example above, the plot size was fixed at 400 by 300 pixels. For dynamic resizing, it's possible to use values from `session$clientData` to detect the output size.
In the example below, the output object is `output$myImage`, and the width and height on the client browser are sent via `clientData$output_myImage_width` and `clientData$output_myImage_height`. This example also uses `clientData$pixelratio` to multiply the resolution of the image, so that it appears sharp on high-resolution (Retina) displays:
In the example below, the output object is `output$myImage`, and the width and height on the client browser are sent via `session$clientData$output_myImage_width` and `session$clientData$output_myImage_height`. This example also uses `session$clientData$pixelratio` to multiply the resolution of the image, so that it appears sharp on high-resolution (Retina) displays:
#### server.R
{% highlight r %}
shinyServer(function(input, output, clientData) {
shinyServer(function(input, output, session) {
# A dynamically-sized plot
output$myImage <- renderImage({
# Read myImage's width and height. These are reactive values, so this
# expression will re-run whenever they change.
width <- clientData$output_myImage_width
height <- clientData$output_myImage_height
width <- session$clientData$output_myImage_width
height <- session$clientData$output_myImage_height
# For high-res displays, this will be greater than 1
pixelratio <- clientData$pixelratio
pixelratio <- session$clientData$pixelratio
# A temp file to save the output.
outfile <- tempfile(fileext='.png')