c# - 如何使用派生类中的值填充文本框？C＃

Question

在我的表格中，我有以下...

if (productNo == this.product1.ProductNumber)  //ProductNumber comes from Product class
                {
                    //if so, set the other values of the text boxes to that of the 
                    //product in memory
                    tbDescription.Text = product1.ProductDescription; //Works - from Product class
                    tbOnHand.Text = product1.NumberOnHand.ToString(); //Works - from Product class
                    tbUnitOfMeasure.Text = product1.UnitOfMeasure;    //Works - from Product class

                    tbVendorID.Text = product1.VendorID; // Doesn't work - from derived ManufacturedProduct class 
                }

其中 VendorID 来自 ManufacturedProduct 类，该类是来自 Product 的派生类。最后一行代码是行不通的。我希望能够使用 product1.VendorID 中的值填充 tbVendorID（顺便说一下，它是一个 int）

我收到以下错误...Objects.Product 不包含“VendorID”的定义，并且找不到接受“Objects.Product”类型的第一个参数的扩展方法“VendorID”（您是否缺少 using 指令或装配参考？）

Answer 1

ManufacturedProduct如果要访问子类的属性，则需要将其转换为：

ManufacturedProduct mfgProduct = (ManufacturedProduct) product1;
if (productNo == mfgProduct.ProductNumber)  
{
    tbDescription.Text = mfgProduct.ProductDescription;  
    tbOnHand.Text = mfgProduct.NumberOnHand.ToString();  
    tbUnitOfMeasure.Text = mfgProduct.UnitOfMeasure;    
    tbVendorID.Text = mfgProduct.VendorID;  
}

Answer 2

您可以执行以下操作：

if (productNo == this.product1.ProductNumber)  //ProductNumber comes from Product class
{
        tbDescription.Text = product1.ProductDescription; 
        tbOnHand.Text = product1.NumberOnHand.ToString(); 
        tbUnitOfMeasure.Text = product1.UnitOfMeasure;    
        if(priduct1 is ManufacturedProduct)
               tbVendorID.Text = ((ManufacturedProduct)product1).VendorID.ToString(); 
}