I'd like to send a java.util.HashMap
converted to JSON from the client to the server.
I'm using JSweet to transpile Java to JavaScript for the client side.
I had a look at XMLHttpRequest
and tried to prepare the map for transfer using JSON.stringify(new HashMap<>())
but this resulted in a
TypeError: cyclic object value
on the client side.
These are my relevant dependencies (using Gradle):
// Java to JavaScript transpilation
compile "org.jsweet:jsweet-transpiler:1.2.0-SNAPSHOT"
compile "org.jsweet.candies:jsweet-core:1.1.1"
// Allows us to use Java features like Optional or Collections in client code
compile "org.jsweet.candies:j4ts:0.2.0-SNAPSHOT"
I had to convert the java.util.Map
to a jsweet.lang.Object
before encoding it as JSON using stringify
.
Here's the code to send a java.util.Map
as JSON to the server using JSweet:
void postJson(Map<String, String> map, String url) {
XMLHttpRequest request = new XMLHttpRequest();
// Post asynchronously
request.open("POST", url, true);
request.setRequestHeader("Content-Type", "application/json;charset=UTF-8");
// Encode the data as JSON before sending
String mapAsJson = JSON.stringify(toJsObject(map));
request.send(mapAsJson);
}
jsweet.lang.Object toJsObject(Map<String, String> map) {
jsweet.lang.Object jsObject = new jsweet.lang.Object();
// Put the keys and values from the map into the object
for (Entry<String, String> keyVal : map.entrySet()) {
jsObject.$set(keyVal.getKey(), keyVal.getValue());
}
return jsObject;
}
Use it like this:
Map<String, String> message = new HashMap<>();
message.put("content", "client says hi");
postJson(message, "http://myServer:8080/newMessage");