[{_id:"cap_1"},{_id:"cap_2",features:null},{_id:"cap_3",features:undefined},{_id:"cap_4",features:{}},{_id:"cap_5",features:{other:"whatever"}},{_id:"cap_6",features:{shopAll:null}},{_id:"cap_7",features:{shopAll:undefined}},{"_id":"cap_8","features":{"shopAll":false}},{"_id":"cap_9","features":{"shopAll":true}}]

db.collection.update({},[{$set:{"features.shopAll":true}}],{multi:true})