DDevelopment & Design

Restart or power off Rasperry PI with REST call

If you need to restart or power off your RPi remotely (or through local application’s call) here’s a simple wayhttp://raspberry.address:7000/reboothttp://raspberry.address:7000/power/offDetails and code at  https://github.com/zdanek/raspiPowerServer

If you need to restart or power off your RPi remotely (or through local application’s call) here’s a simple way

http://raspberry.address:7000/reboot
http://raspberry.address:7000/power/off

Details and code at  https://github.com/zdanek/raspiPowerServer

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DDevelopment & Design

Grails render as JSON catch

One of a reasons your controller doesn't render a proper response in JSON format might be wrong package name that you use. It is easy to overlook. Import are on top of a file, you look at your code and everything seems to be fine. Except response is still not in JSON format.

Consider this simple controller:

class RestJsonCatchController {
def grailsJson() {
render([first: 'foo', second: 5] as grails.converters.JSON)
    }

def netSfJson() {
render([first: 'foo', second: 5] as net.sf.json.JSON)
    }
}

And now, with finger crossed... We have a winner!

$ curl localhost:8080/example/restJsonCatch/grailsJson
{"first":"foo","second":5}
$ curl localhost:8080/example/restJsonCatch/netSfJson
{first=foo, second=5}

As you can see only grails.converters.JSON converts your response to JSON format. There is no such converter for net.sf.json.JSON, so Grails has no converter to apply and it renders Map normally.

Conclusion: always carefully look at your imports if you're working with JSON in Grails!

Edit: Burt suggested that this is a bug. I've submitted JIRA issue here: GRAILS-9622 render as class that is not a codec should throw exception