Doubt to insert record with foreign key. ENTITY FRAMEWORK

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Doubt to insert record with foreign key. ENTITY FRAMEWORK

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I'm a beginner (well, beginner) in programming, and I have a case to develop, which would be a Crud, using ASP.NET (C #) and Entity Framework. I've created a simple contact registration form, where there is a company name field. Contact table and Company table, where there is a connection field between the two. In the register I inform the name of the company. How do I save the company code in the foreign key field when writing this form, first enter the record in the company table, and then in the foreign key field?

I tried to do something like this, but I could not solve it so far

protected void btnGravar_Click(object sender, EventArgs e)
    {
        using (ModelConexao db = new ModelConexao())
        {

            Contato contato = new Contato()
            {
                nome = txtNome.Text,
                telefone = txtTelefone.Text,
                email = txtEmail.Text,
                idEmpresa = db.Empresa
                 .Where(c => c.nome == txtEmpresa.Text)
                 .Select(c => c.codigo)
            };                          

            db.Contato.Add(contato);
            db.SaveChanges();
        }

        this.DataBind()

The idea is that when registering enter the registration in the secondary table (company), and look for the company code (CompanyID) to save in the Contact, connecting this field.

c# asp.net entity-framework

asked by anonymous 07.04.2018 / 02:24

1 answer

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score 0 · Answer 1

When we use Entity , we can not set the ID field to the value of the primary table, we should use it in object form. Make a query and make a variable in object, and arrow its object empresa of class Contato , as in the example below:

    using (ModelConexao db = new ModelConexao())
    {
     var empresa = db.Empresa.Where(c => c.nome == txtEmpresa.Text).FirstOrDefault();

        Contato contato = new Contato()
        {
            nome = txtNome.Text,
            telefone = txtTelefone.Text,
            email = txtEmail.Text,
            Empresa = empresa
        };                          

        db.Contato.Add(contato);
        db.SaveChanges();
    }

    this.DataBind()