+ toJSON = function()
+ {
+ fields <- sapply(private$classFields, function(field)
+ {
+ self[[field]]
+ }, USE.NAMES = TRUE)
+
+ jsonlite::toJSON(list("collection" =
+ Filter(Negate(is.null), fields)), auto_unbox = TRUE)
+ },
+
+ isEmpty = function() {
+ fields <- sapply(private$classFields,
+ function(field) self[[field]])
+
+ if(any(sapply(fields, function(field) !is.null(field) && field != "")))
+ FALSE
+ else
+ TRUE
+ },
+