db.createCollection("proceedings",

{validator:{$jsonSchema:{

   bsonType: "object",

   required:["title","editors","publisher","volume","year",

                 "inproceedings","rating"],

   additionalProperties:false,

   properties:{

      _id: {},

      title:{bsonType: "string",description: "it is required"},

      editors:{bsonType: "array",description: "it is required",

        minItems:1, items: {bsonType: "string"}},

      publisher:{bsonType: "string",description: "it required"},

      isbn:{bsonType: "string",description: "it is optional"},

      volume:{bsonType: "int",description: "it is required"},

      year:{bsonType: "int",description: "it is required"},

      rating:{bsonType: "string",	enum: ["A", "B", "C"],

        description: "required and restricted to values A, B and C"},

      inproceedings:{bsonType: "array",

             description: "it is an array of inproceedings",

          minItems:1,items:{bsonType: "object",

        required: ["title", "authors", "pages", "year", "ee", "url"],

        additionalProperties: false,

        properties:{

          title:{bsonType:"string",description: "it is required"},

          authors:{bsonType:"array",

            minItems: 1,items:{bsonType:"string"}},

          pages:{bsonType:"string"},

          year: {bsonType: "int"},

          ee: {bsonType: "string"},

          url: {bsonType: "string"}}}}}}}

})