データの妥当性確認

Question

私はプログラミングとC＃を初めて使いました。小さな電子投票システムを作ろうとしています。投票者が余分な数の候補者に投票すると、票を無効にする方法はありますか？例：ユーザーが評議員の位置に7つの候補の代わりに、6を投票し、どのように私は彼の投票は無効にすることができたり、彼がそれ6.

private void btn_submit_Click(object sender, EventArgs e) 
    { 
     con.Open(); 
     if (MessageBox.Show("Confirm and View your Votes?", "Close Application", MessageBoxButtons.YesNo) == DialogResult.Yes) 
     { 
      MessageBox.Show("Voting Successful", "Application Closed!", MessageBoxButtons.OK); 

      using (SqlCommand command = new SqlCommand("UPDATE candidate SET cTally = cTally + 1 where cName like @cname or cName like @vName", con)) 
      { 

       command.Parameters.AddWithValue("@cname", cb_president.Text); 
       command.Parameters.AddWithValue("@vName", cb_vpresident.Text); 
       command.ExecuteNonQuery(); 

      } 
      foreach (object item in lb_councilor.SelectedItems) 
      { 
       using (SqlCommand command = new SqlCommand("UPDATE candidate SET cTally = cTally + 1 where cName like @coname", con)) 
       { 

        command.Parameters.AddWithValue("@coname", (item as DataRowView)["cName"].ToString()); 

        Console.WriteLine((item as DataRowView)["cName"].ToString()); 
        command.ExecuteNonQuery(); 

       } 
       using (SqlCommand command = new SqlCommand("UPDATE voters SET isVoted = 1 where userName like @uname", con)) 
       { 

        command.Parameters.AddWithValue("@uname", userid); 

        command.ExecuteNonQuery(); 

       } 
      } 
      this.Close(); 
      new Form4().Show(); 
      this.Hide(); 


     } 
     else 
     { 
      this.Activate(); 
     } 
    } 

    private void Frm_voteview_Load(object sender, EventArgs e) 
    { 
     SqlConnection con = new SqlConnection(Properties.Settings.Default.VotingSystemv2ConnectionString); 
     con.Open(); 

     // TODO: This line of code loads data into the 'votingSystemv2DataSet7.candidate' table. You can move, or remove it, as needed. 
     this.candidateTableAdapter2.Fill(this.votingSystemv2DataSet7.candidate); 
     // TODO: This line of code loads data into the 'votingSystemv2DataSet5.candidate' table. You can move, or remove it, as needed. 
     this.candidateTableAdapter1.Fill(this.votingSystemv2DataSet5.candidate); 
     // TODO: This line of code loads data into the 'votingSystemv2DataSet4.candidate' table. You can move, or remove it, as needed. 
     this.candidateTableAdapter.Fill(this.votingSystemv2DataSet4.candidate); 

    } 

    private void dgv_councilor_CellMouseDown(object sender, DataGridViewCellMouseEventArgs e) 
    { 

    } 

    private void dgv_councilor_RowHeaderMouseClick(object sender, DataGridViewCellMouseEventArgs e) 
    { 

    } 

    private void Frm_voteview_FormClosed(object sender, FormClosedEventArgs e) 
    { 
     SqlConnection con = new SqlConnection(Properties.Settings.Default.VotingSystemv2ConnectionString); 
     // TODO: This line of code loads data into the 'votingSystemv2DataSet7.candidate' table. You can move, or remove it, as needed. 
     this.candidateTableAdapter2.Fill(this.votingSystemv2DataSet7.candidate); 
     // TODO: This line of code loads data into the 'votingSystemv2DataSet5.candidate' table. You can move, or remove it, as needed. 
     this.candidateTableAdapter1.Fill(this.votingSystemv2DataSet5.candidate); 
     // TODO: This line of code loads data into the 'votingSystemv2DataSet4.candidate' table. You can move, or remove it, as needed. 
     this.candidateTableAdapter.Fill(this.votingSystemv2DataSet4.candidate); 
     con.Close(); 
    } 

    private void button1_Click(object sender, EventArgs e) 
    { 
     new Form9().Show(); 
    } 

    private void cb_president_SelectedIndexChanged(object sender, EventArgs e) 
    { 

    } 

    private void lb_councilor_SelectedIndexChanged(object sender, EventArgs e) 
    { 

    } 
} 

}

Answer 1

作るまで、彼は彼の票を提出することはできません。現在、あなたのコードはデータベースに直接書き込んでおり、データベースからビューを引き出しています。あなたがSeparation of Concernsのためにしようとしている場合は、簡単にこの問題を解決するかもしれません

View < > Database 

：その関係を図式化すると次のようになります。

C＃では、ビューとデータベースの間にある私たちのロジックの一部を追跡するオブジェクトを作成することができます。

using System.Collections.Generic; 

public class Poll 
{ 
    var this.Candidates = new List<Candidate>(); 
    var this.MaxVotes; 

    Poll(List<Candidate> candidates, int allowedVotes) 
    { 
     this.Candidates = candidates; 
     this.MaxVotes = allowedVotes; 
    } 

    public Vote(List<Candidate> selectedCandidates) 
    { 
     if (selectedCandidates.Count > this.MaxVotes) 
     { 
      // throw a new Exception or warn the user if the user has too many votes and make them fix it 
     } 

     else // If the vote passes our check, we can save it to the database 
     { 
      // save the votes to the database 
     } 
    } 
} 

public class Candidate 
{ 
    this.Name; 

    Candidate(string name) 
    { 
     this.Name = name; 
    } 
}