presentation.slide

MongoDB with Go

Cory LaNou, InfluxDB
cory@influxdb.com
@corylanou

* What is MongoDB

MongoDB (from "humongous") is an open-source document database, and the leading NoSQL database. Written in C++.

.link http://www.mongodb.org/ MongoDB

* What is NoSQL

Trivia bonus question: What does "NoSQL" stands for?

* NoSQL

It does NOT mean "no sql"

It means "Not only SQL"

* Setting up MongoDB

Since installing MongoDB goes beyond the scope of this presentation,
we will use mongolab.

.link https://mongolab.com/ mongolab home page

.link https://mongolab.com/signup/ 1) Sign up

.link https://mongolab.com/create 2) Create instance

3) Select "Single-Node", then "Sandbox".  This is the free option.

4) Give it the database name "beginning_go".

5) Click "Create New Mongo Deployment"

* mongolab instance url and password

To find the url and password, click the name of the newly created instance.

In this case "beginning_go"

* Add a user

.link https://mongolab.com/databases/beginning_go#users Add user

username: go
password: I will tell you this at presentation time

* Connecting

If you have the mongo tools installed locally, you can connect to your instance like this:

	mongo <url>/beginning_go -u <dbuser> -p <dbpassword>

This is not necessary for this workshop

* mgo

mgo (pronounced as mango) is a MongoDB driver for the Go language that implements a rich and well tested selection of features under a very simple API following standard Go idioms.

To get the library locally, run this command at the command line:

	go get gopkg.in/mgo.v2

.link http://godoc.org/gopkg.in/mgo.v2 API Documentation

* spew

This is a go library we will use to "pretty print" from our examples.

	go get github.com/davecgh/go-spew/spew

.link https://github.com/davecgh/go-spew API Documentation

* Setting up our environment

We will need some environment variables to make our life easier.

*Mac/Linux*

	export mongo_url=<your url>
	export mongo_user=go
	export mongo_password=<your password>
	export mongo_collection=to_dos

Test this by running:

	printenv | grep mongo

*Windows*

	set mongo_url=<your url>
	set mongo_user=go
	set mongo_password=<your password>
	set mongo_collection=to_dos

* Environment Variables - Advice

I create a local _dev.env_ file that I source and add it to my *.gitignore* file so it doesn't check in.

This allows me to quickly open the project, run:

	source dev.env
	
and have all necessary environment variables
for my local project set up.

Summary:

1) Create dev.env file.
2) Add necessary environment variables
3) Add "dev.env" to your ".gitignore" file if using git
4) run:

	source dev.env

* Creating a session - Imports

Define the package and imports we will use:

.code 01_session/main.go /START IMPORT OMIT/,/END IMPORT OMIT/

* Creating a session - Main block

Open the "main" block

.code 01_session/main.go /START MAIN OMIT/,/END MAIN OMIT/

* Creating a session - Getting environment variables

Get our environment variables

.code 01_session/main.go /START ENV OMIT/,/END ENV OMIT/

.link http://golang.org/pkg/os/ os package documenation

* Creating a session - Declare some local variables

Decalre some local variables

.code 01_session/main.go /START VAR OMIT/,/END VAR OMIT/


* Creating a session - Dialing up the server

Dial up the server

.code 01_session/main.go /START DIAL OMIT/,/END DIAL OMIT/

.link http://golang.org/pkg/fmt/ fmt package documenation

* Creating a session - Getting the collection

Get our collection

.play 01_session/main.go /START FINAL OMIT/,/END FINAL OMIT/


* Creating a session - Running the example

To run this:

	go run main.go

You should get something like this returned:

	Collection: &{Database:0xc20801ed40 Name:to_dos FullName:beginning_go.to_dos}

Here is the entire file:

.link https://github.com/corylanou/go-mongo-presentation/blob/master/01_session/main.go main.go

* Structs and Tags - Imports

.code 02_structs/main.go /START IMPORT OMIT/,/END IMPORT OMIT/

* Structs and Tags - Type and struct tags

.code 02_structs/main.go /START TYPE OMIT/,/END TYPE OMIT/

.link http://golang.org/pkg/reflect/#StructTag API documentation on StructTag

*Note:* Getting struct tags wrong can make your life miserable.  Be sure to always run go vet on your code:

	go vet ./...

You may need to install go vet first:

	go get -u golang.org/x/tools/cmd/vet

* Structs and Tags - creating a todo

.play 02_structs/main.go /START MAIN OMIT/,/END MAIN OMIT/

* Structs and Tags - Running the example

To run this:

	go run main.go

You should get something like this returned:

	(main.Todo) {
	Task: (string) (len=8) "Demo mgo",
		Created: (time.Time) 2015-01-10 11:06:39.876506859 -0700 MST,
		Updated: (time.Time) 0001-01-01 00:00:00 +0000 UTC,
		Completed: (time.Time) 0001-01-01 00:00:00 +0000 UTC
	}


Here is the entire file:

.link https://github.com/corylanou/go-mongo-presentation/blob/master/02_structs/main.go main.go

*NOTE:* Zero Time can be detected

.link http://golang.org/pkg/time/#Time.IsZero Time.IsZero

* Upserting data - Adding BSON import

.code 03_upsert/main.go /START IMPORT OMIT/,/END IMPORT OMIT/

.link http://godoc.org/gopkg.in/mgo.v2/bson mgo bson API documentation

* Upserting data - Adding ID to the Todo type

.code 03_upsert/main.go /START TYPE OMIT/,/END TYPE OMIT/

*NOTE:* There are some tricks you will want to do here for ID if you are going to serialize to JSON.  We'll cover this at the end of the presentation.

* Upserting data - Upsert the data

.play 03_upsert/main.go /START FINAL OMIT/,/END FINAL OMIT/

Here is the entire file:

.link https://github.com/corylanou/go-mongo-presentation/blob/master/03_upsert/main.go main.go

* Reading/Writing via Find/Apply

.play 04_read_write/main.go /START CHANGE OMIT/,/END CHANGE OMIT/

Here is the entire file:

.link https://github.com/corylanou/go-mongo-presentation/blob/master/04_read_write/main.go main.go


* Aggregation - Results Type Definition

.code 05_aggregation/main.go /START TYPE OMIT/,/END TYPE OMIT/

* Aggregation - Seeding data

.code 05_aggregation/main.go /START SEED OMIT/,/END SEED OMIT/

* Aggregation - Pipeline

.code 05_aggregation/main.go /START PIPELINE OMIT/,/END PIPELINE OMIT/

* Aggregation - Results

.code 05_aggregation/main.go /START RESULTS OMIT/,/END RESULTS OMIT/


* Aggregation - Iter

.play 05_aggregation/main.go /START ITER OMIT/,/END ITER OMIT/

*NOTE:* You will have to remove your existing data before running this as we changed the structure.

* ID fields and the downfalls of BSON

If you serialize this struct to JSON and then back from json to this struct, the world will blow up.

To avoid this, we create a type for the ID as a string and add some bson magic.

.code 06_ids/main.go /START TYPE OMIT/,/END TYPE OMIT/

* ID - As a type

.code 06_ids/main.go /START TYPE_ID OMIT/,/END TYPE_ID OMIT/

This also has the side benefit of never allowing me to specify another ID as a TODO ID.

Example, I have a placeID and a userID, even though they are both strings, now with a custom type I can never assign a userID to a placeID in the struct.


* ID - Boilerplate

.code 06_ids/main.go /START BOILERPLATE OMIT/,/END BOILERPLATE OMIT/

*NOTE:* In go 1.4 this would be a great use of the generate tool


* ID - BSON Marshalling

.code 06_ids/main.go /START BSON OMIT/,/END BSON OMIT/

.link http://godoc.org/gopkg.in/mgo.v2/bson#Getter BSON Getter
.link http://godoc.org/gopkg.in/mgo.v2/bson#Setter BSON Setter

* Stubbing and testing calls to the database

Stubbing out our calls allows us to create quick unit tests instead of actually calling into the database.


* The interface

Declaring an interface allows you to create a stub in your tests later

.code 07_stubbing_and_testing/handler.go /START TYPE OMIT/,/END TYPE OMIT/

* The handler PART 1

There are many ways to attach context to your handlers, this is a simple way but there are better ways.

.code 07_stubbing_and_testing/handler.go /START HANDLER1 OMIT/,/END HANDLER1 OMIT/


* The handler PART 2

.code 07_stubbing_and_testing/handler.go /START HANDLER2 OMIT/,/END HANDLER2 OMIT/

Here is the entire file:

.link https://github.com/corylanou/go-mongo-presentation/blob/master/07_stubbing_and_testing/handler.go handler.go

* The stub

.code 07_stubbing_and_testing/handler_test.go /START STUB OMIT/,/END STUB OMIT/

* Testing Found - Setting up the stub

.code 07_stubbing_and_testing/handler_test.go /START FOUND1 OMIT/,/END FOUND1 OMIT/

* Testing Found - Setting up the http test

.code 07_stubbing_and_testing/handler_test.go /START FOUND2 OMIT/,/END FOUND2 OMIT/

.link http://golang.org/pkg/net/http/httptest/#pkg-examples httptest

* Testing Not Found

.code 07_stubbing_and_testing/handler_test.go /START NOTFOUND1 OMIT/,/END NOTFOUND1 OMIT/
.code 07_stubbing_and_testing/handler_test.go /START NOTFOUND2 OMIT/,/END NOTFOUND2 OMIT/

* Testing Internal Server Error

.code 07_stubbing_and_testing/handler_test.go /START SERVERERROR1 OMIT/,/END SERVERERROR1 OMIT/
.code 07_stubbing_and_testing/handler_test.go /START SERVERERROR2 OMIT/,/END SERVERERROR2 OMIT/