# How to connect to Mongodb in local?

#### » Start mongodb with docker

# please install docker on your local
docker run --name mongodb -p 27017:27017 -d mongo

#### » Run the mongo images

# 檢查是否有mongodb image
$ docker images 
REPOSITORY   TAG       IMAGE ID       CREATED       SIZE
mongo        latest    f03be0dc25f8   5 weeks ago   448MB

# 檢查 mongodb container 執行
$ docker ps
CONTAINER ID   IMAGE     COMMAND                  CREATED        STATUS        PORTS                      NAMES
6024e7a8bf47   mongo     "docker-entrypoint.s…"   10 hours ago   Up 10 hours   0.0.0.0:27017->27017/tcp   mongodb

# 啟動 docker container
$ docker start [Container ID]

# 停止 docker container
$ docker stop [Container ID]

#### » If NOT any running container

# [OPTIONS]:
# -i, --interactive (互動模式)
# -t, --tty         (配置一個終端機)
# -d, --deactivate (背景執行)

$ docker run -it -d mongo

#### » For more information click [here](https://hub.docker.com/_/mongo)

## Create a new python project

#### ① Poetry create one project

# use poetry as package management(instead pip)
$ poetry new mongoengine-tutorial

# enter the project
$ cd mongoengine-tutorial

#### ② Create the poetry.toml

# make sure the venv is in project dir
$ echo "[virtualenvs]\nin-project = true" > poetry.toml

#### ③ Build the virtual environment

# use shell to create a .venv directory
$ poetry shell

# install the usage packages 
$ poetry install

#### ④ Install the mongoengine (For more information click [here](https://docs.mongoengine.org/tutorial.html))

# use poetry add as the same above
$ poetry add mongoengine

## MongoEngine(Python)
### After start the mongodb container & create project

#### ① create the main script

$ cd mongodb-tutorial
$ touch main.py

#### ② import mongoengine

from mongoengine import (
    connect,
    Document,
    StringField,
    ReferenceField,
    ListField,
    EmbeddedDocumentField,
    EmbeddedDocument,
    CASCADE,
)

#### ③ connect to the mongodb container

# connect('my_db', host='127.0.0.1', port=27017)
connect("tumblelog")

#### ④ create the model(user / comment / post) for blog

# User model that save the user instance
class User(Document):
    first_name = StringField(max_length=50)
    last_name = StringField(max_length=50)
    email = StringField(required=True)


class Comment(EmbeddedDocument):
    content = StringField()
    name = StringField(max_length=120)


class Post(Document):
    title = StringField(max_length=120, required=True)
    author = ReferenceField(User, reverse_delete_rule=CASCADE)
    tags = ListField(StringField(max_length=30))
    comments = ListField(EmbeddedDocumentField(Comment))

    # allow for inherit, because of differnet type of post
    meta = {"allow_inheritance": True}
    

# Polymorphism
class TextPost(Post):
    content = StringField()


class ImagePost(Post):
    image_path = StringField()


class LinkPost(Post):
    link_url = StringField()

#### ⑤ new the user & post

# Ross
ross = User(
    email="[e-mail]", 
    first_name="Ross", 
    last_name="Lawley")
)
ross.save()

# John
john = User(
    email="[e-mail]", 
    first_name="Roe",
    last_name="Kail")
)
john.save()


# create two comments (EmbbededDcoument won't be save)
msg1 = Comment(
    name="jamie",
    content="What is the price?"
)

msg2 = Comment(
    name="howard",
    content="Where to buy it?"
)
message.save()


# create the text post
post1 = TextPost(
    title="Fun with MongoEngine", 
    author="john",
    comment=[msg1, msg2],
    content="Took a look at MongoEngine today, looks pretty cool.",
    tags = ["mongodb", "mongoengine"]
)

post1.save()

# create the link post
post2 = LinkPost(
    title="MongoEngine Documentation", 
    author=ross, 
    link_url = "http://docs.mongoengine.com/"
)
post2.tags = ["mongoengine"]
post2.save()


for post in Post.objects:
    print(post.to_json()
    

#### ⑥ run the main.py script

$ python3 main.py

# Output
{
   "_id":{
      "$oid":"608f4fe0d510f3eb1f733a44"
   },
   "_cls":"Post.TextPost",
   "title":"Fun with MongoEngine",
   "author":"john",
   "tags":[
      "mongodb",
      "mongoengine"
   ],
   "comments":[
      {
         "content":"How's going?",
         "name":"jamie"
      },
      {
         "content":"What are you doing?",
         "name":"howard"
      }
   ],
   "content":"Took a look at MongoEngine today, looks pretty cool."
}

{
   "_id":{
      "$oid":"608f509657dc7ce331a9bf42"
   },
   "_cls":"Post.LinkPost",
   "title":"MongoEngine Documentation",
   "author":{
      "$oid":"608f509657dc7ce331a9bf3f"
   },
   "tags":[
      "mongoengine"
   ],
   "comments":[
      
   ],
   "link_url":"http://docs.mongoengine.com/"
}

### Reference:
- [mongodb docker images](https://hub.docker.com/_/mongo)
- [mongoengine](https://docs.mongoengine.org/tutorial.html#getting-started)
###### tags: `mongodb`