Adding new child record to binding source using Entity Framework

Question

Hi all Having 1 winForm with 2 grids bound to bindingsource controls: 1 grid for categories (master) and 1 grid for Products (detail)  data and relationship are well loaded. Now I try to add a new (master) record to categories: For the next two cases I get issues: First case: When I click + button without entering anything  New Category is not added and I gat the message: Cannot insert the value NULL into column 'CategoryName' table 'Northwind.dbo.Categories'; column does not allow nulls. INSERT fails.
The statement has been terminated. spite of filling it by code. Second case: When I click + button and enter manually something in the CategoryName cell after clicking save button it is persisted but I get the message: The changes to the database have been validated but an error has occurred while updating the object context. ObjectContext might be in an inconsistent state. Internal exception message: AcceptChanges can not continue because the key values of the object are in conflict with another object in ObjectStateManager. Make sure key values are unique before calling AcceptChanges. Here is my code: namespace MyNameSpace { public partial class Form1 : Form { public Form1() { InitializeComponent(); } NorthwindEntities ctx; bool _adding; private void Form2_Load(object sender EventArgs e) { ctx = new NorthwindEntities(); categoriesBindingSource.DataSource = ctx.Categories; } private void categoriesBindingSource_AddingNew(object sender AddingNewEventArgs e) { _adding = true; } private void categoriesBindingSource_CurrentChanged(object sender EventArgs e) { if (_adding) { categoriesBindingSource.EndEdit(); var newCat = (Categories)categoriesBindingSource.Current; if (newCat.Products == null) { Products Prd = new Products(); Prd.Discontinued = false; Prd.ProductName = New Product Name; ctx.AddToProducts(Prd); } newCat.CategoryName =  New Category; ctx.AddToCategories(newCat); _adding = false; } } private void categoriesBindingNavigatorSaveItem_Click(object sender EventArgs e) { categoriesBindingSource.EndEdit(); ctx.SaveChanges(); } Please any help ?

Samio · Answer

Hi Brunda tried your solution and the issue remains the same. Thank you

brunda k · Answer

private void categoriesBindingNavigatorSaveItem_Click(object sender EventArgs e) { categoriesBindingSource.EndEdit(); productsBindingSource.EndEdit(); ctx.SaveChanges(); } http://blogs.msdn.com/b/bethmassi/archive/2009/09/15/inserting-master-detail-data-into-a-sql-server-compact-edition-database.aspx

Samio · Answer

thanks for your help Murali 1/- Adding or removing this: categoriesBindingSource.EndEdit() to categoriesBindingSource_CurrentChanged event do nothing while running the code. 2/- I assume that you proposed to persist first the parent to have an ID so I used it like this: newCat.CategoryName =  New Category; ctx.AddToCategories(newCat); if (newCat.Products == null) { Products Prd = ctx.Products.Where(c=>c.ProductID == newCat.CategoryID).First(); Prd.Discontinued = false; Prd.ProductName = New Product Name; ctx.AddToProducts(Prd); } But finally the the issues remain the same. Just for information I've tried the same task using Linq 2 SQL instead of EF it run like a charm.

Muralidharan Deenathayalan · Answer

Please check the following in your categoriesBindingSource_CurrentChanged method. 1) You've called  categoriesBindingSource.EndEdit();  . Is this correct ? 2) First add the category into context object and add the product into context object. newCat.CategoryName =  New Category; ctx.AddToCategories(newCat); if (newCat.Products == null) { Products Prd = new Products(); Prd.Discontinued = false; Prd.ProductName = New Product Name; ctx.AddToProducts(Prd); } First make sure the parent object is there or not. If it is not there create the parent object and refer the parent id to the child object. If you want to do any validation before adding category please do it. Let me know if this is helps you or not.