flask-mongoengine扩展¶

time:2018-09-25

flask的扩展，提供了与MongoEngine的集成，详细查看MongoEngine的文档 http://docs.mongoengine.org/

安装flask-mongoengine:

pip install flask-mongoengine

config配置:

MONGODB_DB = ''
MONGODB_HOST = ''
MONGODB_PORT = '27017'
MONGODB_USERNAME = ''
MONGODB_PASSWORD = ''

默认情况下，flask-mongoengine会在实例化扩展时打开连接，但您可以将其配置为仅在第一次访问数据库时打开连接:

MONGODB_CONNECT=False

自定义查询

get_or_404 ：与get类似，如果查询到没有对象返回abort(404)
first_or_404: 同上。
paginate：数据集分页传递两个参数，page和per_page。
paginate_field ：在查询中一个文档进行分页，参数：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)

分页对象的属性包括：iter_pages，next，prev，has_next，has_prev，next_num，prev_num。

template:

{# Display a page of todos #}
<ul>
{% for todo in paginated_todos.items %}
    <li>{{ todo.title }}</li>
{% endfor %}
</ul>

{# Macro for creating navigation links #}
{% macro render_navigation(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 %}

{{ render_navigation(paginated_todos, 'view_todos') }}

与WTForms的集成¶

flask-mongoengine自动从MongoEngine模型生成WTForms:

from flask_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)

如果不是隐式转换，则允许提示用户参数:

PostForm = model_form(Post, field_args={'title': {'textarea': True}})

支持的参数:

choices:

multiple to use a SelectMultipleField
radio to use a RadioField

StringField:

password to use a PasswordField
textarea to use a TextAreaField

默认情况下，没有设置max_length时，StringField才会转换为TextAreaField。

支持的字段:

StringField
BinaryField
URLField
EmailField
IntField
FloatField
DecimalField
BooleanField
DateTimeField
ListField(使用wtforms.fields.FieldList)
SortedListField(重复ListField)
EmbeddedDocumentField(使用wtforms.fields.FormField并生成内联表单)
ReferenceField(使用带有从QuerySet或Document加载的选项的wtforms.fields.SelectFieldBase)
DictField

目前不支持的类型:

ObjectIdField
GeoLocationField
GenericReferenceField

Session 会话¶

要使用MongoEngine作为会话存储，只需配置会话接口:

from flask_mongoengine import MongoEngine, MongoEngineSessionInterface

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

Flask-DebugToolbar:

from flask import Flask
from flask_debugtoolbar import DebugToolbarExtension

app = Flask(__name__)
db = MongoEngine(app)
toolbar = DebugToolbarExtension(app)

#config.py：
DEBUG_TB_PANELS = 'flask_mongoengine.panels.MongoDebugPanel'