How to post data to (the new) content property API endpoint?

[Neil]

I just installed Confluence 5.6.1 in order to use the new API endpoints for custom properties

https://docs.atlassian.com/atlassian-confluence/REST/latest/#d3e86

When I try to post a new property I am getting a 500 error

var req = new XMLHttpRequest();
req.open("GET", APIcall, false);
req.send(null);
console.log(req.responseText);
var somejson = JSON.parse(req.responseText);

console.log(somejson);
//EVERYTHING WORKS GREAT UNTIL HERE
jQuery.ajax({
	contentType: 'application/json',
	type: 'POST',
	url: contextPath + "/rest/api/content/13238557/property",
	data: somejson,
	success: function(response) {
	console.log(response);
}
//And then BOOM! 500 error. API URL works great in my browser...

Besides this, I've tried various things in the REST API browser, all to no avail. Not sure what I am doing wrong 

Thank you in advance!

---

This question is jumping off of this one right here

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EDIT: This is my working solution for pulling saving JSON data with in a page. Thank you for the help everyone.

<script type="text/javascript">
var APIcall="http://apicallthatreturnssomejson.com";

var request = new XMLHttpRequest();
request.open("GET", APIcall, false);
request.send(null);
console.log(request.responseText);
var response = JSON.parse(request.responseText);

jQuery.ajax({
	contentType: 'application/json',
	type: 'POST',
	url: contextPath + "/rest/api/content/" + $content.id + "/property",
	data: JSON.stringify({key:"mykey", value:response}),
	processData: false,
	success: function(postresponse) {
	console.log(postresponse);
}
});

[Tiago Comasseto]

Hi Neil, have you tried to send this REST call using curl to eliminate variables and see if it works? I've just tested it using the example JSON and it worked here:

$ curl -D- -u admin:admin -X POST --data "{\"key\":\"example-property-key\",\"value\":{\"anything\":\"goes\"},\"content\":{\"id\":\"360456\",\"type\":\"page\",\"_links\":{\"self\":\"http://192.168.10.224:8561/rest/api/content/360456\"},\"_expandable\":{\"body\":\"\",\"container\":\"\",\"ancestors\":\"\",\"children\":\"\",\"descendants\":\"\",\"metadata\":\"\"}},\"version\":{\"number\":2,\"minorEdit\":false},\"_links\":{\"base\":\"http://192.168.10.224:8561\",\"context\":\"\",\"self\":\"http://192.168.10.224:8561/rest/api/content/360456/property/example-property-key\"}}" -H "Content-Type: application/json" http://192.168.10.224:8561/rest/api/content/360456/property
HTTP/1.1 200 OK
Server: Apache-Coyote/1.1
X-ASEN: SEN-L3897800
Set-Cookie: JSESSIONID=CF1289EE83FD4FBD3772C34DEB65CB9D; Path=/; HttpOnly
X-Seraph-LoginReason: OK
X-AUSERNAME: admin
X-Content-Type-Options: nosniff
Content-Type: application/json
Transfer-Encoding: chunked
Date: Tue, 09 Sep 2014 14:04:24 GMT

{"id":"360457","key":"example-property-key","value":{"anything":"goes"},"version":{"when":"2014-09-09T11:04:24.136-0300","message":"","number":1,"minorEdit":false},"_links":{"base":"http://192.168.10.224:8561","context":"","self":"http://192.168.10.224:8561/rest/api/content/360456/property/example-property-key"},"_expandable":{"content":"/rest/api/content/360456"}}

Cheers

[Neil]

OK! That worked! Now... what is all that other stuff in the data object? (_links, _self, _expandable etc) At least some of it is clearly necessary. Is it that documented somewhere that I missed?

[Muhammad Ali]

have you found the required data objects documentation

[Scott Branden]

Please take we off all the mailing lists!  I'm getting atlassian emails starting the last few days!