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Flask-MongoEngine

一個用來集成MongoEngine的Flask擴展，更多MongoEngine詳細信息請參看MongoEngine文檔。

它處理應用的連接管理。你也可以用WTForms作為模型的格式。

安裝Flask-MongoEngine

使用pip安裝：

pip install flask-mongoengine

配置

基本步驟很簡單，僅需獲取擴展：

from flask import Flask
from flask.ext.mongoengine import MongoEngine

app = Flask(__name__)
app.config.from_pyfile('the-config.cfg')
db = MongoEngine(app)

或者，若你想在應用初始化之前配置數據庫，下方是一個應用工廠的列子：

from flask import Flask
from flask.ext.mongoengine import MongoEngine
db = MongoEngine()
...
app = Flask(__name__)
app.config.from_pyfile('the-config.cfg')
db.init_app(app)

默認情況下，Flask-MongoEngine假設mongod實例運行在本地主機的27017端口上，并且你將連接名為test的數據庫。

如果MongoDB運行在別處，你需要在app.config的'MONGODB_SETTINGS'字典中配置主機和端口：

app.config['MONGODB_SETTINGS'] = {
  'db': 'project1',
  'host': '192.168.1.35', 
  'port': 12345
}

如果數據庫需要身份驗證，app.config['MONGODB_SETTINGS']字典需要提供username、password參數：

app.config['MONGODB_SETTINGS'] = {
  'db': 'project1', 
  'username':'webapp', 
  'password':'pwd123'
}

也支持Uri風格的連接，僅需在app.config['MONGODB_SETTINGS']字典中將host值設為uri。注意，自uri獲取的數據庫名稱優先級高于本地設置：

app.config['MONGODB_SETTINGS'] = {
  'db': 'project1', 
  'host': 'mongodb://localhost/database_name'
}

連接配置也可以通過帶有MONGODB_前綴的字典單獨設置：

app.config['MONGODB_DB'] = 'project1'
app.config['MONGODB_HOST'] = '192.168.1.35'
app.config['MONGODB_PORT'] = 12345
app.config['MONGODB_USERNAME'] = 'webapp'
app.config['MONGODB_PASSWORD'] = 'pwd123'

定制查詢集

flask-mongoengine位MongoEngine的默認查詢集附加了下列方法：

• get_or_404:類似于.get(),但若對象不存在，返回404中止。
• first_or_404:類似于.first(),并做404判斷。
• paginate:為查詢集分頁。需要倆個參數，page和per_page。
• paginate_field:用查詢集中某個文檔的字段分頁。參數：field_name, doc_id, page, per_page.

例子：

# 404 if object doesn't exist
def view_todo(todo_id):
    todo = Todo.objects.get_or_404(_id=todo_id)
..

# Paginate through todo
def view_todos(page=1):
    paginated_todos = Todo.objects.paginate(page=page, per_page=10)

# Paginate through tags of todo
def view_todo_tags(todo_id, page=1):
    todo = Todo.objects.get_or_404(_id=todo_id)
    paginated_tags = todo.paginate_field('tags', page, per_page=10)

分頁對象包含以下屬性： iter_pages, next, prev, has_next, has_prev, next_num, prev_num.

在模板中：

{% macro render_pagination(pagination, endpoint) %}
  <div class=pagination>
  {%- for page in pagination.iter_pages() %}
    {% if page %}
      {% if page != pagination.page %}
        <a href="{{ url_for(endpoint, page=page) }}">{{ page }}</a>
      {% else %}
        <strong>{{ page }}</strong>
      {% endif %}
    {% else %}
      <span class=ellipsis>…</span>
    {% endif %}
  {%- endfor %}
  </div>
{% endmacro %}

MongoEngine 和 WTForms

你可以這樣使用MongoEngine 和 WTForms：

from flask.ext.mongoengine.wtf import model_form

class User(db.Document): 
  email = db.StringField(required=True) 
  first_name = db.StringField(max_length=50) 
  last_name = db.StringField(max_length=50)

class Content(db.EmbeddedDocument): 
  text = db.StringField() 
  lang = db.StringField(max_length=3)

class Post(db.Document): 
  title = db.StringField(max_length=120, required=True, validators=[validators.InputRequired(message=u'Missing title.'),]) 
  author = db.ReferenceField(User) 
  tags = db.ListField(db.StringField(max_length=30)) 
  content = db.EmbeddedDocumentField(Content)

PostForm = model_form(Post)

def add_post(request): 
  form = PostForm(request.POST) 
  if request.method == 'POST' and form.validate(): 
    # do something 
    redirect('done') 
  return render_template('add_post.html', form=form)

支持字段

• StringField
• BinaryField
• URLField
• EmailField
• IntField
• FloatField
• DecimalField
• BooleanField
• DateTimeField
• ListField (using wtforms.fields.FieldList )
• SortedListField (duplicate ListField)
• EmbeddedDocumentField (using wtforms.fields.FormField and generating inline Form)
• ReferenceField (using wtforms.fields.SelectFieldBase with options loaded from QuerySet or Document)
• DictField

目前不支持字段類型：

• ObjectIdField
• GeoLocationField
• GenericReferenceField

Session Interface

To use MongoEngine as your session store simple configure the session interface:

from flask.ext.mongoengine import MongoEngine, MongoEngineSessionInterface

app = Flask(__name__)
db = MongoEngine(app)
app.session_interface = MongoEngineSessionInterface(db)

調試工具欄面板

調試工具欄面板.png

如果你使用Flask-DebugToolbar，你可以添加

app.config['DEBUG_TB_PANELS'] = ['flask.ext.mongoengine.panels.MongoDebugPanel']

，然后它將自動跟蹤查詢：

from flask import Flask
from flask_debugtoolbar import DebugToolbarExtension

app = Flask(__name__)
app.config['DEBUG_TB_PANELS'] = ['flask.ext.mongoengine.panels.MongoDebugPanel']
db = MongoEngine(app)
toolbar = DebugToolbarExtension(app)

升級

ListFieldPagination參數的順序已經改變的更為符合邏輯：

# Old order
ListFieldPagination(self, queryset, field_name, doc_id, page, per_page, total)
# New order
ListFieldPagination(self, queryset, doc_id, field_name, page, per_page, total)