danared

db.homeSales.findOne()
{
  "_id": ObjectId("56005dd980c3678b19792b7f"),
  "amount": 9000,
  "date": ISODate("1996-09-19T00:00:00Z"),
  "address": {
    "nameOrNumber": 25,
    "street": "NORFOLK PARK COTTAGES",
    "town": "MAIDENHEAD",
    "county": "WINDSOR AND MAIDENHEAD",

danared

db.orders.runCommand("collMod", 
                   {validationLevel: "strict", 
                    validationAction: "error"});

danared

db.orders.update(
    {price:"free"},
    {$set: {price: 0}},
    {multi: true});

db.orders.update(
    {price:"if you have to ask...."},
    {$set: {price: 1000000}},
    {multi: true});

danared

secondary> db.orders.aggregate([
    {$match: {
      price: {$type: 2}}},
    {$group: {
      _id: "$price", 
      count: {$sum:1}}}
  ])

{ "_id" : "if you have to ask....", "count" : 250 }
{ "_id" : "free", "count" : 500 }

danared

db.orders.findOne({price: {$type: 2}});

{
  "_id": 3500,
  "item": "abc",
  "price": "free",
  "quantity": 5
}

> db.orders.update(

danared

db.orders.insert({
    "_id": 6666, 
    "item": "jkl", 
    "price": "rogue",
    "quantity": 1 });

Document failed validation
WriteResult({
  "nInserted": 0,
  "writeError": {

danared

db.orders.runCommand("collMod", 
                   {validationLevel: "moderate", 
                    validationAction: "error"});

db.runCommand({collMod: "orders", 
               validator: {
                  price: {$exists: true},
                  price: {$type: 1}
                }
              });

danared

use clusterdb;
db.dropDatabase();
use clusterdb();
db.inventory.insert({ "_id" : 1, "sku" : "abc", 
    "description" : "product 1", "instock" : 120 });
db.inventory.insert({ "_id" : 2, "sku" : "def", 
    "description" : "product 2", "instock" : 80 });
db.inventory.insert({ "_id" : 3, "sku" : "ijk", 
    "description" : "product 3", "instock" : 60 });
db.inventory.insert({ "_id" : 4, "sku" : "jkl", 

danared

db.runCommand({
   collMod: "contacts",
   validator:
     {$or: [{version: {"$exists": false}},
            {version: 1,
             $and: [{Name: {"$exists": true}}]
            },
            {version: 2,
             $and: [{Name: {"$exists": true, "$type": 2}}]
            }

danared

db.runCommand({
   collMod: "contacts",
   validator: { 
      $and: [
        {year_of_birth: {$lte: 1994}},
        {$or: [ 
                  {phone: { $type: "string"}}, 
                  {email: { $type: "string"}}
              ]}]
    }})