Hi I want to create a feature from the Editor widget and when its created i want to apply the value in the back end which needs to updated on the attr

[JeffreyWilkerson]

Since the Editor widget is creating your feature you can't pass any attributes at creation, you need to set up an event monitor for the layer being edited, and then when that occurs create the attribute for the feature and save it using Apply Edits.

Maybe something like this:

aLayer.on("apply-edits", function (results) {
    
    if (results.edits.addFeatures) {
        var newObjectId = results.addFeatureResults[0]["objectId"]; 
        console.log("Added new feature with objectID: ", newObjectId);
        var edit = [{"id" : 0, 
            "updates": [
                "attributes": {
                  "OBJECTID": newObjectId,
                  "datetime": 1272210710000,
                  "Somefield": "This is an updated value" 
                } 
            ]
        }]
        var promise = aLayer.applyEdits(edit);
        console.log(promise);
    }
})