C# WinForms - Saving to database via Entity

Question

Hey!

I'm building some sort of customer management program and am running aground currently. I have two tables, 'customers' and 'contacts'. In my WinForm I have 2 textboxes and 1 combobox. The textboxes will have the values Name and FirstName for the table contacts respectively and the combobox selects 1 customer from the customers table and I need the ID of that customer to be inserted into contacts aswell. What is the smartest way to do this? I've been trying different things for quite some time now and have not gotten anywhere.

Answer 1

Hello,

Please indicate either in words or code what you have tried and how you created your entities.

Also what version of EF is being used.

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Answer 2

In fact it is easy, you need to do SaveChanges

https://msdn.microsoft.com/en-us/library/system.data.entity.dbcontext.savechanges(v=vs.113).aspx

The documentation around this is really unmicrosoft. 

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Success
Cor

Answer 3

Hi Hootcake,

According to your description, if you use entity framework, which is a one-to-many relationship, one contact has many customers, which model will be like below:

public class Contract
{ 
    public int ContractId  { get; set; } 
    public string Address { get; set; } 
    public virtual ICollection<Customer> Customers { get; set; } 

    public Contract() 
    {
        Customers = new Collection<Customer>();
    }
} 

public class Customer 
{ 
    public int Id { get; set; } 
    public string CustomerName { get; set; } 
    // foreign key of Contract table
    public int ContractId { get; set; } 
    public virtual Contract Contract {get; set;}
}

If you want to insert a customer into database, please try the following code.

 using (var db = new EFDemoContext())
{

     Customer custom = new Customer();
     custom.Id = 1;
     custom.CustomerName = "Test";
     custom.ContractId  = //From your combobox's value
     db.Customers.Add(custom);
     db.SaveChanges();
}

Best regards,

Zhanglong

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