What is the best way to validate data in mongo?

Question

What's the best way to validate data being inserted or updated into MongoDB? Is it to write some sort of server executed Javascript code that does the validation?

Answer 1

Starting MongoDB 3.6 you can also use JSON Schema to express validation rules. These checks will happen on the database side on insert/update.

Here is an example from the docs:

   validator = {
      $jsonSchema: {
         bsonType: "object",
         required: [ "name", "year", "major", "address" ],
         properties: {
            name: {
               bsonType: "string",
               description: "must be a string and is required"
            },
            year: {
               bsonType: "int",
               minimum: 2017,
               maximum: 3017,
               description: "must be an integer in [ 2017, 3017 ] and is required"
            },
            major: {
               enum: [ "Math", "English", "Computer Science", "History", null ],
               description: "can only be one of the enum values and is required"
            },
            gpa: {
               bsonType: [ "double" ],
               description: "must be a double if the field exists"
            },
            address: {
               bsonType: "object",
               required: [ "city" ],
               properties: {
                  street: {
                     bsonType: "string",
                     description: "must be a string if the field exists"
                  },
                  city: {
                     bsonType: "string",
                     description: "must be a string and is required"
                  }
               }
            }
         }
      }
   }

db.runCommand( {
   collMod: "collectionName",
   validator: validator
} )