#mongodb shell

[thetheoryofcode]

Introduction to MongoDB - JSON, mongodb shell, compass and Atlas

Welcome to the MongoDB Video Series. This is the first video of the MongoDB series and in this video I'll introduce you to MongoDB ecosystem which includes 1. JavaScript Object Notation (JSON) 2. MongoDB database, Collections and Documents 3. MongoDB Compass 4. MongoDB JS shell 5. MongoDB Atlas We'll not only understand these but will also create, modify and delete documents via MongoDB JS shell as well as via MongoDB compass #Mongodb #NoSQL #javascript #nodejs #js #mongodb compass #mongodbatlaa #mongoshell #node

[mongodb]

Meet Variety, a Schema Analyzer for MongoDB

Variety is a lightweight tool which gives a feel for an application's schema, as well as any schema outliers. It is particularly useful for

• quickly learning how data is structured, if inheriting a codebase with a production data dump

• finding all rare keys in a given collection

An Easy Example

We'll make a collection, within the MongoDB shell:

db.users.insert({name: "Tom", bio: "A nice guy.", pets: ["monkey", "fish"], someWeirdLegacyKey: "I like Ike!"}); db.users.insert({name: "Dick", bio: "I swordfight."});  db.users.insert({name: "Harry", pets: "egret"}); db.users.insert({name: "Geneviève", bio: "Ça va?"});

$ mongo test --eval "var collection = 'users'" variety.js

The above is executed from terminal."test" is the database containing the collection we are analyzing.

Variety's output:

{ "_id" : { "key" : "_id" }, "value" : { "types" : [ "object" ] }, "totalOccurrences" : 4, "percentContaining" : 100 } { "_id" : { "key" : "name" }, "value" : { "types" : [ "string" ] }, "totalOccurrences" : 4, "percentContaining" : 100 } { "_id" : { "key" : "bio" }, "value" : { "types" : [ "string" ] }, "totalOccurrences" : 3, "percentContaining" : 75 } { "_id" : { "key" : "pets" }, "value" : { "types" : [ "string", "array" ] }, "totalOccurrences" : 2, "percentContaining" : 50 }

{ "_id" : { "key" : "someWeirdLegacyKey" }, "value" : { "type" : "string" }, "totalOccurrences" : 1, "percentContaining" : 25 }

Every document in the “users” collection has a "name" and "_id". Most, but not all have a "bio". Interestingly, it looks like "pets" can be either an array or a string. The application code really only expects arrays of pets. Have we discovered a bug, or a remnant of a previous schema?

The first document created has a weird legacy key I've never seen before- the people who built the prototype didn't clean up after themselves. These rare keys, whose contents are never used, have a strong potential to confuse developers, and could be removed once we verify our findings.

For future use, results are also stored a varietyResults database.

Learn More!

Learn more about Variety now, including

• How to download Variety

• How to set a limit on the number of documents analyzed from a collection

• How to contribute, and report issues

Variety is free, open source, and written in 100% JavaScript. Check it out on Github.

-by James Cropcho