Why Do I Get Validation Errors Saving Data to SQL Server with Entity Framework?

Validation Fails While Saving Changes to SQL Server Database using Entity Framework

When working with ASP.NET MVC 3/C# using Entity Framework Code-First, it is possible to encounter validation errors when saving changes to a SQL Server database. These errors can occur due to mismatches between data types in the entity class and the database.

In this scenario, the Event class defines data types as DateTime and TimeSpan, while the database expects Date and Time data types for the EventDate, StartTime, and EndTime properties. This discrepancy can lead to validation errors.

To resolve the issue, it is necessary to cast the values to the appropriate data types before saving the changes to the database. Here's how:

// Convert DateTime to Date
theEvent.EventDate = theEvent.EventDate.Date;

// Convert TimeSpan to Time
theEvent.StartTime = (theEvent.StartTime.Hours <= 12) 
                      ? theEvent.StartTime 
                      : new TimeSpan(theEvent.StartTime.Hours - 12, theEvent.StartTime.Minutes, theEvent.StartTime.Seconds);

theEvent.EndTime = (theEvent.EndTime.Hours <= 12) 
                 ? theEvent.EndTime 
                 : new TimeSpan(theEvent.EndTime.Hours - 12, theEvent.EndTime.Minutes, theEvent.EndTime.Seconds);

These conversions ensure that the data types match between the entity class and the database, allowing the changes to be successfully saved.

By understanding the potential data type mismatches and implementing the necessary conversions, developers can resolve validation errors and effectively save changes to their SQL Server database using Entity Framework.

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