Question

我目前正在从事一个学术图书馆系统项目（我是一个非常基本的C＃用户），并且我正在尝试实施验证，当前仅使用客户名称进行测试，并使用了错误提供程序工具。< / p>

我已经实现了验证，其中一个字段应仅接受字母/数字/等（Regex.IsMatch），但是现在我想实现验证，其中，在单击“保存客户按钮”时，如果“名称”文本框为EMPTY / NULL，在生成/保存新的客户记录之前，将生成一条警告，提示需要提交名称字段（必填）。目前，我已经尝试执行此操作，但是出现了一些错误。

请注意，在创建新客户（提交所有必填字段时）后，新记录将插入到我与Visual Studio连接的本地数据库中。请参阅下面的代码以供参考。

P.S。我知道我需要努力使用3层/ MVC结构的实现。

namespace Library_System_Project
{
    public partial class AddCustomerRecordForm : Form
    {
        public AddCustomerRecordForm()
        {
            InitializeComponent();
        }

        private void btnSave_Click(object sender, EventArgs e)
        {
            // START Validation
            Customer myCustomer = new Customer();

            String Name;
            String Surname;
            DateTime DateofBirth;
            String Address;
            int TelephoneNumber;
            int MobileNumber;

            Boolean quit = true;

            do
            {
                Name = this.txtName.Text;

                if (Name != null)
                {
                    if (Name == "")
                    {
                        MessageBox.Show("Customer's name is required. Please do not leave this field empty.");

                        this.erp_Provider.SetError(this.txtName, "Customer's name is required. Kindly submit the details in the given field.");

                        quit = true;

                        break;
                    }

                    else
                    {
                        quit = false;

                        this.erp_Provider.Dispose();
                    }
                }

                else
                {
                    return;
                }

            //ABOVE - END Validation

            //BELOW - START DB Connection / Insert upon Save

            string ConnectionString = @"Data Source=.\SQLEXPRESS;AttachDbFilename= C:\Program Files\Microsoft SQL Server\MSSQL14.SQLEXPRESS\MSSQL\DATA\Library System Project.mdf ;Integrated Security=True;Connect Timeout=30";

            string Query = "insert into Customers (CustomerName, CustomerSurname, CustomerDateofBirth, CustomerAddress, CustomerTelephoneNumber, CustomerMobileNumber) values ('" + this.txtName.Text.Trim() + "','" + this.txtSurname.Text.Trim() + "','" + this.msktxtDateofBirth.Text.Trim() + "','" + this.txtAddress.Text.Trim() + "','" + this.txtTelephoneNumber.Text.Trim() + "','" + this.txtMobileNumber.Text.Trim() + "');";

            SqlConnection DBCon = new SqlConnection(ConnectionString);
            SqlCommand DBCommand = new SqlCommand(Query, DBCon);
            SqlDataReader DBReader;

            try
            {
                DBCon.Open();
                DBReader = DBCommand.ExecuteReader();
                MessageBox.Show("New customer record added to the system.", "Library System", MessageBoxButtons.OK);

                while (DBReader.Read())
                {

                }
            }

            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

Answer 1

我已经稍微整理了一下代码，并做了一些修改，认为对您有帮助。

namespace Library_System_Project
{
    public partial class AddCustomerRecordForm : Form
    {
        public AddCustomerRecordForm()
        {
            InitializeComponent();
        }

        private void btnSave_Click(object sender, EventArgs e)
        {
            // START Validation
            Customer myCustomer = new Customer();

            String Name;
            String Surname;
            DateTime DateofBirth;
            String Address;
            // *** You may want these to be strings ***
            int TelephoneNumber;
            int MobileNumber;

            Name = this.txtName.Text;

            if (string.IsNullOrWhiteSpace(Name))
            {
                MessageBox.Show("Customer's name is required. Please do not leave this field empty.");

                // *** Where is this declared ? ***
                // *** I've declared an instance in a using scope so it is disposed of automatically ***
                using(var erp_provider = new ErrorProvider())
                    erp_Provider.SetError(this.txtName, "Customer's name is required. Kindly submit the details in the given field.");
                // *** Return if validation fails ***
                return;
            }

            //ABOVE - END Validation

            //BELOW - START DB Connection / Insert upon Save

            string ConnectionString = @"Data Source=.\SQLEXPRESS;AttachDbFilename= C:\Program Files\Microsoft SQL Server\MSSQL14.SQLEXPRESS\MSSQL\DATA\Library System Project.mdf ;Integrated Security=True;Connect Timeout=30";

            string Query = "insert into Customers (CustomerName, CustomerSurname, CustomerDateofBirth, CustomerAddress, CustomerTelephoneNumber, CustomerMobileNumber) values ('" + this.txtName.Text.Trim() + "','" + this.txtSurname.Text.Trim() + "','" + this.msktxtDateofBirth.Text.Trim() + "','" + this.txtAddress.Text.Trim() + "','" + this.txtTelephoneNumber.Text.Trim() + "','" + this.txtMobileNumber.Text.Trim() + "');";

            SqlConnection DBCon = new SqlConnection(ConnectionString);
            SqlCommand DBCommand = new SqlCommand(Query, DBCon);
            SqlDataReader DBReader;

            try
            {
                DBCon.Open();
                DBReader = DBCommand.ExecuteReader();
                MessageBox.Show("New customer record added to the system.", "Library System", MessageBoxButtons.OK);

                while (DBReader.Read())
                {

                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }finally
            {
                // *** If you're going to be opening a connection be sure to close it ***
                // *** Finally blocks work well for this ***
                DBCon.Close()
            }
        }

    }
}

实施表单验证（其中必填字段不得为空/空）C＃

1 个答案: