generalised insert into sqlalchemy using dictionary

Question

I'm building an application in Flask and I have several SQLAlchemy models defined. I have a dictionary with key/value pairs for each of the model types.

I want a generalised insert using a dictionary... would this require a mapper? I know that wtforms.ext.sqlalchemy.orm.model_form() generates an object with populate_obj(model) so it is possible. I've combed through the documentation but can't find it. I can perform the commit later, but need a shortcut to populate the object for now. Please, does anyone have expertise?

from flask import Flask from flask.ext.sqlalchemy import SQLAlchemy  app = Flask(__name__) db = SQLAlchemy() db.init_app(app)  employee_data = {'firstname':'John','lastname':'Smith'} project_data = {'name':'project1'}  dict_generalised_insert(model=Employee,dictionary=employee_data) dict_generalised_insert(model=Project,dictionary=project_data)  def dict_generalised_insert(model=None,dictionary={})     obj = model.model()      obj.populate_obj(dictionary) # ???     return obj  class Employee(db.Model):     id = db.Column(db.Integer, primary_key=True)     firstname = db.Column(db.String(80))     lastname = db.Column(db.String(80))  class Project(db.Model):     id = db.Column(db.Integer, primary_key=True)     name = db.Column(db.String(80)) 

Answer 1

The idiomatic way to unpack a dictionary is to use the double star operator **.

To use it with flask-sqlalchemy:

class Employee(db.Model)     id = db.Column(...)     firstname = db.Column(...)     lastname = db.Column(...)  employee_data = {'firstname':'John','lastname':'Smith'} employee = Employee(**employee_data) db.session.add(employee) db.session.commit() 

Be aware that the keys in the dictionary have to match the attribute names of the class. Unpacking in this manner is the same as:

employee = Employee(firstname='John', lastname='Smith') 

You can also do this with a list if you define an __init__ (or other method) with positional arguments however you only use a single star:

def __init__(self, firstname, lastname):     self.firstname = firstname     self.lastname = lastname  employee_data = ['John', 'Smith'] employee = Employee(*employee_data) ... 

Note here the order of the values is what's important.