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 sqlalchemy DataTables::"No data available in table" when using self-joined table
#1
Hello,

I need to run a query with sqlalchemy on self-joined table, I tried to use alias as suggested by many forums but no data displayed.
Please find below my code:

models.py

class Employee(db.Model):

__tablename__ = 'employee' #self referenced table

id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(200), nullable=False)
surname = db.Column(db.String(200), nullable=False)
email = db.Column(db.String(200), nullable=False)
id_emp_sup = db.Column(db.Integer, db.ForeignKey("employee.id"))
#emp_sup = db.relationship('Employee',backref = 'employee')
#emp_sup = db.relationship('Employee', foreign_keys="[id_emp_sup]")
id_structure = db.Column(db.Integer, db.ForeignKey("structure.id"))
id_function = db.Column(db.Integer, db.ForeignKey("function.id"))

def __init__(self, name, surname, email, id_emp_sup, id_structure):
self.name = name
self.surname = surname
self.email = email
self.id_emp_sup = id_emp_sup
self.id_structure = id_structure
self.id_function = id_function

views.py

Emp = db.aliased(Employee)


columns = [
ColumnDT(Employee.name +' '+ Employee.surname),
ColumnDT(Emp.name +' '+ Emp.surname)
]
result = db.session.query().select_from(Employee).join(Emp)
params = request.args.to_dict()
rowTable = DataTables(params, result, columns)
return jsonify(rowTable.output_result())


I want to display the full name of each employee with his manager (identified by id_emp_sup) by using sqlalchemy datatable.
Larz60+ wrote Nov-22-2018, 10:28 PM:
Please post all code, output and errors (it it's entirety) between their respective tags. Refer to BBCode help topic on how to post. Use the "Preview Post" button to make sure the code is presented as you expect before hitting the "Post Reply/Thread" button
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