Display Error message after oData Update - odata

Question

I perform an update via my OData service like this:
oModel.create('/Carriers', oEntry, null, function () {
oModel.refresh();
sap.m.MessageBox.show("Saved", sap.m.MesESS);
}, function (err) {
var message = $(err.response.body).find('message').first().text();
sap.m.MessageBox.show(message, sap.m.MessageBox.Icon.ERROR);
});
If I get an error message in the response I am unable to display the message text.
I create the error like this:
CALL METHOD lo_message_container->add_message_text_only
EXPORTING
iv_msg_type = 'E'
iv_msg_text = msg_text.
RAISE EXCEPTION TYPE /iwbep/cx_mgw_busi_exception
EXPORTING
message_container = lo_message_container.
ENDIF.
The err.response.body looks like this:
"{"error":{"code":"SY/530","message":{"lang":"en","value":"This
is the error I am trying to show)"},
"innererror":{"transactionid":"B20B61E5143BF10E92CB000C29D28D3A","timestamp":"20150922092421.4230000","Error_Resolution":{"SAP_Transaction":"Run
transaction /IWFND/ERROR_LOG on SAP NW Gateway hub system and search
for entries with the timestamp above for more details","SAP_Note":"See
SAP Note 1797736 for error analysis
(https://service.sap.com/sap/support/notes/1797736)"},"errordetails":[{"code":"","message":"This
is the error I am trying to show
","propertyref":"","severity":"error","target":""},{"code":"/IWBEP/CX_MGW_BUSI_EXCEPTION","message":"","propertyref":"","severity":"error","target":""}]}}}"
I was trying this but it does not work...
var message = $(err.response.body).find('message').first().text();
sap.m.MessageBox.show(message, sap.m.MessageBox.Icon.ERROR);

Answer 1

It looks like your error is mistaking JSON for a DOM object.
jQuery (the $-sign function) is meant to select DOM elements with the tag name, classes or the id.
To find the right key in an JSON structure, you can use normal JavaScript dot- or brackets-notation:
var message = err.response.body.error.message.value;