Question

I want to invoke a validation function inside the entities objects right before they are stored with ObjectContext#SaveChanges(). Now, I can keep track of all changed objects myself and then loop through all of them and invoke their validation methods, but I suppose an easier approach would be implement some callback that ObjectContext will invoke before saving each entity. Can the latter be done at all? Is there any alternative?

Answer 1

I’ve figured out how. Basically, we can intercept SavingChanges event of ObjectContext and loop through the newly added/modified entities to invoke their validation function. Here’s the code I used.

    partial void OnContextCreated()     {         SavingChanges += PerformValidation;     }      void PerformValidation(object sender, System.EventArgs e)     {         var objStateEntries = ObjectStateManager.GetObjectStateEntries(             EntityState.Added | EntityState.Modified);          var violatedRules = new List<RuleViolation>();         foreach (ObjectStateEntry entry in objStateEntries)         {             var entity = entry.Entity as IRuleValidator;             if (entity != null)                 violatedRules.AddRange(entity.Validate());         }         if (violatedRules.Count > 0)             throw new ValidationException(violatedRules);     }