Python-сообщество

 Purchase order {{ order.order_no }}
Status {{ order.status | upper }}
Supplied by - {{ order.supplier_name }}
{% if order.received_datetime %}Received date - {{ order.received_datetime }}{% endif %}
{% for line in order.lines -%}
{{ line.product_name }}, quantity - {{ line.quantity }}
{% endfor -%}

 from jinja2 import Environment, FileSystemLoader
template_env = Environment(loader=FileSystemLoader('./'))
class PurchaseOrderLine:
    def __init__(self, product_name, quantity):
        self.product_name = product_name
        self.quantity = quantity
class PurchaseOrder:
    def __init__(self, order_no, supplier_name, received_datetime=None):
        self.order_no = order_no
        self.status = 'draft'
        self.supplier_name = supplier_name
        self.received_datetime = received_datetime
        self.lines = []
    def add_line(self, line):
        self.lines.append(line)
if __name__ == '__main__':
    order = PurchaseOrder(1, 'Supplier')
    order.add_line(PurchaseOrderLine(product_name='Bread', quantity=2))
    order.add_line(PurchaseOrderLine(product_name='Milk', quantity=3))
    template = template_env.get_template('order.txt')
    text = template.render({'order': order})
    print(text)

Purchase order 1
Status DRAFT
Supplied by - Supplier
Received date - 2019-03-07 13:19:14.589757
Bread, quantity - 2
Milk, quantity - 3

Purchase order 1
Status DRAFT
Supplied by - Supplier

Bread, quantity - 2
Milk, quantity - 3

 Purchase order {{ order.order_no }}
Status {{ order.status | upper }}
Supplied by - {{ order.supplier_name }}{% if order.received_datetime %}\nReceived date - {{ order.received_datetime }}{% endif %}
{% for line in order.lines -%}
{{ line.product_name }}, quantity - {{ line.quantity }}
{% endfor -%}

 Purchase order 1
Status DRAFT
Supplied by - Supplier\nReceived date - 2019-03-07 19:01:39.410241
Bread, quantity - 2
Milk, quantity - 3

 Purchase order {{ order.order_no }}
Status {{ order.status | upper }}
Supplied by - {{ order.supplier_name }}{% if order.received_datetime %}
Received datetime - {{ order.received_datetime }}{% endif %}
{% for line in order.lines -%}
{{ line.product_name }}, quantity - {{ line.quantity }}
{% endfor -%}