[minor] check if date of joining is available before creating Salary …

…Slip (#8700)

erpnext/hr/doctype/salary_slip/salary_slip.py

@@ -321,9 +321,13 @@ def check_existing(self):
 	def sum_components(self, component_type, total_field):
 		joining_date, relieving_date = frappe.db.get_value("Employee", self.employee,
 			["date_of_joining", "relieving_date"])
+
 		if not relieving_date:
 			relieving_date = getdate(self.end_date)
 
+		if not joining_date:
+			frappe.throw(_("Please set the Date Of Joining for employee {0}").format(frappe.bold(employee.employee)))
+
 		for d in self.get(component_type):
 			if ((cint(d.depends_on_lwp) == 1 and not self.salary_slip_based_on_timesheet) or\
 			getdate(self.start_date) < joining_date or getdate(self.end_date) > relieving_date):

erpnext/hr/doctype/salary_structure/salary_structure.py

@@ -33,6 +33,7 @@ def validate_date(self):
 		for employee in self.get('employees'):
 			joining_date, relieving_date = frappe.db.get_value("Employee", employee.employee,
 				["date_of_joining", "relieving_date"])
+
 			if employee.from_date and joining_date and getdate(employee.from_date) < joining_date:
 				frappe.throw(_("From Date {0} for Employee {1} cannot be before employee's joining Date {2}")
 					    .format(employee.from_date, employee.employee, joining_date))