Displaying dynamically generated images in Yesod

问题

I'm writing my first Yesod app. The application involves the user selecting to view a graph, dynamically generated based on data stored in a DB on the server. I know how to get the user request and create the image on the server's file system, but how do I create a response page presenting it?

P.S. As I'm using GnuPlot to generate the image, I only know how to write it as a file to the file system, but If you happen to know how to get the data in memory it'll probably be even better. Thanks,

回答1:

For a file on disk, you can use sendFile in your handler.

getImageR = do
    -- ... save image data to disk somewhere
    sendFile typeJpeg "/path/to/file.jpg"

For sending it from a ByteString in memory, use sendResponse.

getImageR = do
    bytes <- -- generate image data
    sendResponse (typePng, toContent bytes)

Make sure you specify the correct content type for your image.

来源：https://stackoverflow.com/questions/7147799/displaying-dynamically-generated-images-in-yesod