MSDN Magazine - July 2008 - (Page 32)

// custom extension method context.SaveChanges(); } Notice that the code in the UpdateCustomer method uses an extension method I named SetAllModified , which makes it easier to set the state of all of the properties for an entity to be modified. SetAllModified gets an instance of the ObjectStateEntry for the given entity T. It then retrieves a list of all of the property names for the entity and iteratively calls SetModifiedProperty for each property: Figure 7 public static void SetAllModified (this T entity, ObjectContext context) where T : IEntityWithKey { var stateEntry = context.ObjectStateManager. GetObjectStateEntry(entity.EntityKey); var propertyNameList = stateEntry.CurrentValues.DataRecordInfo. FieldMetadata.Select (pn => pn.FieldType.Name); foreach (var propName in propertyNameList) stateEntry.SetModifiedProperty(propName); } The RefreshMode of StoreWins will overwrite both original and current values in the entity cache with the values from the database. ClientWins is the appropriate strategy for last-in-wins, while StoreWins is an appropriate strategy when you want to cancel the changes and refresh the UI’s view with the latest database values: context.Refresh(RefreshMode.ClientWins, customer); // Last in wins Another way to ultimately save the entity is to call the context’s Refresh method. This tells the context to go get the data for the entity instance and refresh its property values from the database’s values. The RefreshMode enumerator of ClientWins will replace the original values with the latest values from the database, thus MSDN Swordfish Half Horz.ai 17/3/08 4:48:37 PM allowing a last-in-wins strategy. The Entity Framework enforces optimistic concurrency when generating update and delete commands. It does this by including original values in the WHERE clause for any properties with a ConcurrencyMode attribute value set to Fixed. By default, models are generated with no fields specified as concurrency fields. This means that when a user saves his changes, he possibly could be overwriting another user’s changes inadvertently. If another user changes a value while the CustomerView is Get moving. Stay focused. Take control. Enterprise Architect from Sparx Systems redefines visual modeling with a huge set of built-in tools, technologies and capabilities, coupled with a lightweight footprint and great agility. With deep support for UML 2.1 and its related standards, Enterprise Architect 7.1 is the ideal tool to analyze, design, build and manage your next software project. Keep your project moving, keep your team focused and stay in total control. 32 Visitmsdn magazine sparxsystems.com for a free trial Data Points http://sparxsystems.com http://sparxsystems.com

Table of Contents Feed for the Digital Edition of MSDN Magazine - July 2008

MSDN Magazine - July 2008 Contents Toolbox CLR Inside Out Flex Your Data Data Points Advanced Basics Office Space Cutting Edge Data Services ADO.NET Data and WPF Transactions WCF P2P Test Run Security Briefs Foundations .NET Matters {End Bracket}

MSDN Magazine - July 2008

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