System.Configuration.ConnectionStringSettingsCollection.this[string].get 返回 null

Question

我在尝试在数据库中插入用户密码时尝试在 salt 和 hash 中创建和保存密码。当我单击注册按钮时，它显示以下错误。

System.NullReferenceException: 'Object reference not set to an instance of an object.'
System.Configuration.ConnectionStringSettingsCollection.this[string].get returned null.

下面我添加了我的注册页面代码。

public class GenerateHash
{
    public string CreateSalt(int SaltSize)
    {
        var rng = new System.Security.Cryptography.RNGCryptoServiceProvider();
        byte[] Salt = new byte[SaltSize];
        rng.GetBytes(Salt);
        return Convert.ToBase64String(Salt);
    }

    public string GenarateHash(string UserPassword, string salt)
    {
        byte[] bytes = System.Text.Encoding.UTF8.GetBytes(UserPassword + salt);
        byte[] PasswordHash = new System.Security.Cryptography.SHA256Managed().ComputeHash(bytes);

        return Convert.ToBase64String(PasswordHash);
    }

    protected void Regist_Click(object sender, EventArgs e)
    {
        GenerateHash HashAndSalt = new GenerateHash();
        string GetSalt = HashAndSalt.CreateSalt(10);
        string hashString = HashAndSalt.GenarateHash(Password.Text, GetSalt);
        string username = UserName.Text;
        string connectionString = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
        using (MySqlConnection conn = new MySqlConnection(connectionString))
        {
            conn.Open();
            using (MySqlCommand cmd = new MySqlCommand("Insert into [User](UserName, PasswordHashed, Salt) values(" + "@UserName, @PasswordHashed, @Salt)", conn))
            {
                cmd.Parameters.AddWithValue("@UserName", username);
                cmd.Parameters.AddWithValue("@PasswordHashed", hashString);
                cmd.Parameters.AddWithValue("@Salt", GetSalt);
                cmd.ExecuteNonQuery();
            }
        }
        Response.Redirect("Login  .aspx");
    }
}

Answer 1

检查 web.config 文件中的连接字符串名称，看看它是否与代码中的 ConnectionString 匹配。

例如：

<connectionStrings>
    <add name="connStr" connectionString="SERVER=localhost;DATABASE=saha;UID=root;PASSWORD=abc123;max pool size=50000000; Allow User Variables=True"/>
  </connectionStrings>

所以在上面的代码中将name="connstr"更改为name="connectionString"。我认为这应该可以解决您的问题。希望对你有帮助。

Answer 2

通常，您会尝试使用其名称从 Web.Config 读取连接字符串：

<connectionStrings>
  <add name="StudentConn" connectionString="Database=XXX;Data Source=XXX;Initial Catalog=XXX;Integrated Security=True"/>

获取日志数据库的连接字符串

public static string Logging { get { return ConfigurationManager.ConnectionStrings["StudentConn"].ConnectionString; } }

System.Configuration.ConnectionStringSettingsCollection.this[string].get 返回 null

System.Configuration.ConnectionStringSettingsCollection.this[string].get returned null

c#

mysql

asp.net-mvc-4