Example for flask-admin issue 874

issue_874.py

import os
import os.path as op

from flask import Flask
from flask_sqlalchemy import SQLAlchemy

from sqlalchemy.event import listens_for

from flask_admin import Admin, form
from flask_admin.contrib import sqla


# Create application
app = Flask(__name__, static_folder='files')

# Create dummy secrey key so we can use sessions
app.config['SECRET_KEY'] = '123456790'

# Create in-memory database
app.config['DATABASE_FILE'] = 'sample_db.sqlite'
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///' + app.config['DATABASE_FILE']
app.config['SQLALCHEMY_ECHO'] = True
db = SQLAlchemy(app)

# Create directory for file fields to use
file_path = op.join(op.dirname(__file__), 'files')
try:
    os.mkdir(file_path)
except OSError:
    pass


# Create models
class File(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.Unicode(64))
    path = db.Column(db.Unicode(128))

    def __unicode__(self):
        return self.name


# Delete hooks for models, delete files if models are getting deleted
@listens_for(File, 'after_delete')
def del_file(mapper, connection, target):
    if target.path:
        try:
            os.remove(op.join(file_path, target.path))
        except OSError:
            # Don't care if was not deleted because it does not exist
            pass


# Administrative views
class FileView(sqla.ModelView):
    # Override form field to use Flask-Admin FileUploadField
    form_overrides = {
        'path': form.FileUploadField
    }

    # Pass additional parameters to 'path' to FileUploadField constructor
    form_args = {
        'path': {
            'label': 'File',
            'base_path': file_path,
            'allow_overwrite': False,
            'allowed_extensions': ['jpg', 'gif', 'png']
        }
    }


# Flask views
@app.route('/')
def index():
    return '<a href="/admin/">Click me to get to Admin!</a>'

# Create admin
admin = Admin(app, 'Example: Forms', template_mode='bootstrap3')

# Add views
admin.add_view(FileView(File, db.session))


def build_sample_db():
    """
    Populate a small db with some example entries.
    """

    db.drop_all()
    db.create_all()

    for i in [1, 2, 3]:
        file = File()
        file.name = "Example " + str(i)
        file.path = "example_" + str(i) + ".pdf"
        db.session.add(file)

    db.session.commit()
    return

if __name__ == '__main__':

    # Build a sample db on the fly, if one does not exist yet.
    app_dir = op.realpath(os.path.dirname(__file__))
    database_path = op.join(app_dir, app.config['DATABASE_FILE'])
    if not os.path.exists(database_path):
        build_sample_db()

    # Start app
    app.run(debug=True)