[{name:"Abc-Name",posts:[{title:"Abc-Title",description:"Abc-description",tags:["A","B"]}]}]

db.collection.update({"_id":ObjectId("5a934e000102030405000000")},{$push:{posts:{$each:[{title:"Abc",description:"abcabcabcabc",tags:["aa","bb","cc"]},{title:"Abc",description:"abcabcabcabc",tags:["aa","bb","cc"]}]}}})