ALso for Django 2.0 upgrade

forecasts/models.py

@@ -509,7 +509,7 @@ class ResultParameter(models.Model):
     key = models.CharField(max_length=50)
     name = models.CharField(max_length=200)
     description = models.TextField()
-    measurementunit = models.ForeignKey(MeasurementUnit)
+    measurementunit = models.ForeignKey(MeasurementUnit,on_delete=models.CASCADE)
     local_name = None
     
     
@@ -536,7 +536,7 @@ class ResultParameter(models.Model):
             
         
 class ResultParameterLocal(models.Model):
-    result_parameter = models.ForeignKey(ResultParameter)
+    result_parameter = models.ForeignKey(ResultParameter,on_delete=models.CASCADE)
     local_name = models.CharField(max_length=200)
     language_code = models.CharField(max_length=2, verbose_name=_("Language code"))
 
@@ -551,9 +551,9 @@ class HighChartsType(models.Model):
 
 class ModelGraphParameter(models.Model):
     model_id = models.CharField(max_length=10, validators=[validate_model_id_length])
-    resultparameter = models.ForeignKey(ResultParameter)
+    resultparameter = models.ForeignKey(ResultParameter,on_delete=models.CASCADE)
     color_hexcode = models.CharField(max_length=6)
-    highcharts_type = models.ForeignKey(HighChartsType)
+    highcharts_type = models.ForeignKey(HighChartsType,on_delete=models.CASCADE)
     
     def __unicode__(self): 
         return self.model_id + "/" + self.resultparameter.getNamespaceKey()