ComboBox 的 SelectedIndexChanged 事件 - 填充控件值

Question

When ComboBox SelectedIndexChanged event occurs, I need to populate the respective controls with its values. I am using entity framework 6 for the approach. I am using c# windows forms and .net framework 4.5. My code is :

private void comboBoxCustomer_SelectedIndexChanged(object sender, EventArgs e)
{
    using (ReliableTradersEntities entities = new ReliableTradersEntities())
    {
        m_blouse = new BLOUSE_MEASUREMENT();
        m_pardi = new PARDI_MEASUREMENT();
        m_lengha = new LHENGA_MEASUREMENT();

        var res = from c in entities.CUSTOMERs
                        join p in entities.PARDI_MEASUREMENT on c.CUSTOMERID equals p.CUSTOMERID
                        join l in entities.LHENGA_MEASUREMENT on c.CUSTOMERID equals l.CUSTOMERID
                        join b in entities.BLOUSE_MEASUREMENT on c.CUSTOMERID equals b.CUSTOMERID
                        select new 
                        {

                            p.PARDILENGTH,
                            p.PARDILIMIT,
                            p.SHOULDER,
                            p.SHOULDERTOHEAD,
                            p.HEADTOBACK,
                            p.HALFHEADROUND,
                            p.NIQABLENGTH,
                            p.KAS,
                            l.LHENGALENGTH,
                            l.LHENGALIMIT,
                            l.BELTOPTION,
                            l.ISPOCKET,
                            l.ISZIP,
                            l.STYLE,
                            l.STYLESIZE,
                            l.ALINE,
                            b.BLOUSELENGTH,
                            b.CHEST,
                            b.WAIST,
                            b.SLEEVES,
                            b.NECK,
                            b.POINT,
                            b.BLOUSEOPENING
                        };
        textBoxPL.Text = m_pardi.PARDILENGTH;
    }

}

Answer 1

You have created an anonymous type that is returned in the variable res with all the info extracted by your query. You have not filled the initial three class instances.

You need to initialize your instances using the res variable with

// The query returns an IEnumerable, you need to extract the first element
var x = res.FirstOrDefault();
if(x != null)
{
    m_pardi = new PARDI_MEASUREMENT();
    m_pardi.PARDILENGTH = x.PARDILENGTH;
    .... 
}

But you could use directly the res variable

 var x = res.FirstOrDefault();
 if(x != null)
 {
     textBoxPL.Text = x.PARDILENGTH;
     .... and so on....
 }