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gen_resource_path

Generates a file path where you can save a file to be served in your app.

When to use this function​

1. Generate a serveable path​

Some widgets serve resources (files) to the client, such as image, which serves an image in a given system path. Such widgets can only serve resources that live inside your project's .Magic/served-files/ directory and subdirectories.

gen_resource_path() is a convenience function to be used when you want don't care for the name of the file you want to serve, nor where it lives, as long as it is "serveable", i.e. it lives somewhere inside .Magic/served-files/. gen_resource_path() generates a path with a random file name with a given extension inside .Magic/served-files/generated. You are then supposed to save your file in the returned path and pass this path to the wiget you want.

For instance, consider an app that displays a plot given some user input. The app's logic will look something like this:

plot_object = generate_fancy_plot(...)       # 1. Generate the plot
serveable_path = gen_resource_path("png")
save_fancy_plot(plot_object, serveable_path) # 2. Save the plot
image(plot_path)                             # 3. Serve the plot

2. Avoid Browser Caching​

Aside from conveniently giving you a serveable file path, gen_resource_path() also helps to avoid browser caching issues. For instance, in the above example, suppose that instead of saving the plot in a random serveable path everytime the plot is regenerated we always saved it in the same serveable path. Most browsers will automatically cache the image associated with a path, so newly generated images in the same path would never be requested by these browsers. Serving the newly generated plot in the path returned by gen_resource_path() prevents that from happening.

Function Signature​

function gen_resource_path(extension::String; lifetime::String="session")::String
ArgumentDescription
extensionFile extension String to be appended to the randomly generated path.
lifetimeA String indicating the lifetime of the resource. Possible values: "session" (default) or "app". If "session" is provided, the file will become unavailable after the session is ended. If "app" is provided, the file will become unavailable after the app is stopped.

Return Value​

A random file path inside .Magic/served-files/generated/ with extension extension.