options(encoding="UTF-8")
library(httr)
# use rjstat  package for JSON-Stat
library(rjstat)
# REST request made by the Eurostat query builder HCPI  
url <- "https://ec.europa.eu/eurostat/wdds/rest/data/v2.1/json/en/prc_hicp_mv12r?precision=1&geo=DK&geo=NO&geo=SE&geo=DE&geo=UK&sinceTimePeriod=2012M01&coicop=CP00&unit=RCH_MV12MAVR"
d.tmp<-GET(url)
# get content from d.tmp as text, using fromJSONstat in rjstat 
sbtable <- fromJSONstat(content(d.tmp, "text"))
# get only dataset from sbtable
ds <- sbtable[[1]]
# Show dataset
ds