What Strategies are there for updating a table when you're using a multi-table view to display it.

Question

I'm using a view and am able to create a grid that allows editing of one of the columns. Let's call the table where the column is updated "DepartmentFeeDetail." The view has several joins but up till now the column was editable.
Today I needed to join DepartmentFeeDetail with itself to pick up the debit side of a debit/credit pair. I want to show the gl account number for both
the debit and credit on the same row. I also need to update the value for both debit and credit.
I can no longer edit the column to no surprise. When updating using MSSQLMS I get the following error:
View or function 'MyTestView' is not updatable because the modification affects multiple base tables.
What should my strategy be in lightswitch? The grid is populated by a query that includes my lynq expressions in DepartmentFeeRateQuery_PreprocessQuery. The query may return 1000+ rows. I need to allow the accountant to edit either a single row's column
or enter a value in a field outside the grid and click a button "Apply fee rate to entire page."
All this was working fine until the requirement to show the debit side gl account number and to change the debit side value somehow.
I've tried adding a property to DepartmentFeeDetail but the "Is Computed" property wouldn't allow me to uncheck it. Is there a way to add an editable property for each grid row and initialize it to the
current value of the column returned by the view? I could then update a collection when one of the fields changes. If they change the global value and press "Apply fee rate to entire page"
I can update the collection as well.
Scott Mitchell

Answer 1

What I do is instead of using a View I use a updatable
WCF RIA Service.
This is an example of an updateable method:
public void UpdateQuestionDetailForUser(QuestionDetailForUser objQuestionDetailForUser)
// Get the current user
string strCurrentUserName = System.Web.HttpContext.Current.User.Identity.Name;
// We are under Forms Authentication so if user is blank then we
// are debugging and we are TestUser
if (strCurrentUserName == "")
strCurrentUserName = "TestUser";
// Check for an existing Answer for this Question for this User
var objSurveyAnswer = (from SurveyAnswers in this.Context.SurveyAnswers
where SurveyAnswers.SurveyQuestion.Id == objQuestionDetailForUser.QuestionId
where SurveyAnswers.UserName == strCurrentUserName
select SurveyAnswers).FirstOrDefault();
if (objSurveyAnswer != null)
try // This is an update ****
// Set values
objSurveyAnswer.Choice = Convert.ToInt32(objQuestionDetailForUser.SelectedChoice);
objSurveyAnswer.Comment = objQuestionDetailForUser.Comments;
// Update LightSwitch Database
this.Context.SaveChanges(
System.Data.Objects.SaveOptions.DetectChangesBeforeSave);
catch (Exception ex)
throw new Exception("Error inserting QuestionId " + objQuestionDetailForUser.QuestionId, ex);
else // This is an Insert ****
// Query the GetAllQuestionsForUser method because it calculates if a Question
// is Active or not for the QuestionId being inserted
// If it is not in the collection, do not allow the insert
var objUserQuestion = (from QuestionForUser in this.GetAllQuestionsForUser()
where QuestionForUser.UserName == strCurrentUserName
where QuestionForUser.QuestionId == objQuestionDetailForUser.QuestionId
select QuestionForUser).FirstOrDefault();
if (objUserQuestion != null)
try
// Get the Survey Question
var objSurveyQuestion = (from SurveyQuestions in this.Context.SurveyQuestions
where SurveyQuestions.Id == objQuestionDetailForUser.QuestionId
select SurveyQuestions).FirstOrDefault();
// Create a SurveyAnswer object
SurveyAnswer objNewSurveyAnswer = this.Context.CreateObject<SurveyAnswer>();
// Set values
objNewSurveyAnswer.UserName = strCurrentUserName;
objNewSurveyAnswer.Choice = Convert.ToInt32(objQuestionDetailForUser.SelectedChoice);
objNewSurveyAnswer.Comment = objQuestionDetailForUser.Comments;
objNewSurveyAnswer.SurveyQuestion = objSurveyQuestion;
// Update LightSwitch Database
this.Context.SurveyAnswers.AddObject(objNewSurveyAnswer);
this.Context.SaveChanges(
System.Data.Objects.SaveOptions.DetectChangesBeforeSave);
catch (Exception ex)
throw new Exception("Error inserting QuestionId " + objQuestionDetailForUser.QuestionId, ex);
else
throw new Exception("Error inserting Answer. Answer is not marked Active.");
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