調用另一個函數返回布爾值的函數

Question

我有以下函數，我需要在另一個函數中調用。我不知道該怎麼做？

private int IsValidUser() 
{    
    int result = 0; 
    string strQuery = "Select Email From AUser Where Email = @Email And Password = @Password "; 
    SqlConnection con = new SqlConnection(System.Configuration.ConfigurationManager.AppSettings["ConnectionString"]); 

    SqlCommand Cmd = new SqlCommand(strQuery, con); 
    //Cmd.CommandType = CommandType.StoredProcedure; 

    Cmd.Parameters.AddWithValue("@Email", txtEmail.Text); 
    Cmd.Parameters.AddWithValue("@Password", txtPassword.Text); 
    con.Open(); 

    result = (int)Cmd.ExecuteScalar(); 

    if (result > 0) 
    { 
     //Session["SessionEmail"] = txtEmail.Text; 
     Session[General.S_USEREMAIL] = txtEmail.Text; 
     Response.Redirect("~/frmMyAccountMyProfile.aspx"); 
    } 
    else 
    { 
     Literal1.Text = "Invalid Email/Password!"; 
    } 
} 

我想在按鈕點擊事件時將它稱爲如下所示。

protected void btnSignIn_Click(object sender, EventArgs e) 
{ 
    // Authenticate User 
    bool blnValidUser = false; 
    IsValidUser(); 
    blnValidUser = Convert.ToBoolean(IsValidUser().result.Value); 
    if (blnValidUser) 
    { 
     // on Success - If remember me > Save to cookies 
     //SaveUserDetailsToCookie();      
    } 
    else 
    { 
     // on Failure - Show error msg 
    } 
} 

Answer 1

你的功能IsValidUser用於返回一個int

（無論出於何種原因是未知的我，因爲它沒有返回值。這個代碼將永遠不會編譯。）

你能解決這個問題，有它返回一個bool這樣的：

private bool IsValidUser() 
{ 
     int result = 0; 
     //since executeScalar is intended to retreive only a single value 
     //from a query, we select the number of results instead of the email address 
     //of each matching result. 
     string strQuery = "Select COUNT(Email) From AUser Where Email = @Email And Password = @Password "; 
     SqlConnection con = new SqlConnection(System.Configuration.ConfigurationManager.AppSettings["ConnectionString"]); 

     SqlCommand Cmd = new SqlCommand(strQuery, con); 
     //Cmd.CommandType = CommandType.StoredProcedure; 

     Cmd.Parameters.AddWithValue("@Email", txtEmail.Text); 
     Cmd.Parameters.AddWithValue("@Password", txtPassword.Text); 
     con.Open(); 

     result = (int)Cmd.ExecuteScalar(); 

     //returning a boolean comparator works like this : 
     //will return true if the result is greater than zero, but false if it is not. 
     return result > 0; 
} 

，然後你可以調用你的函數是這樣的：

blnValidUser = IsValidUser(); 

Answer 2

修改函數如下

private int IsValidUser() 
    { 
    int result = 0; 
    string strQuery = "Select Email From AUser Where Email = @Email And Password = @Password "; 
    SqlConnection con = new SqlConnection(System.Configuration.ConfigurationManager.AppSettings["ConnectionString"]); 

    SqlCommand Cmd = new SqlCommand(strQuery, con); 
    //Cmd.CommandType = CommandType.StoredProcedure; 

    Cmd.Parameters.AddWithValue("@Email", txtEmail.Text); 
    Cmd.Parameters.AddWithValue("@Password", txtPassword.Text); 
    con.Open(); 

    result = (int)Cmd.ExecuteScalar(); 

    if (result > 0) 
    { 
     //Session["SessionEmail"] = txtEmail.Text; 
     Session[General.S_USEREMAIL] = txtEmail.Text; 
     Response.Redirect("~/frmMyAccountMyProfile.aspx"); 
    } 

    else 
    { 
     Literal1.Text = "Invalid Email/Password!"; 
    } 
    return result; 

} 
} 

並稱之爲如下

protected void btnSignIn_Click(object sender, EventArgs e) 
{ 
    // Authenticate User 
    int blnValidUser = IsValidUser(); 
    //Check if blnValidUser is greater than 0. 
    //IsValidUser() will return value greater than 0 if the sql is successful else will return 0 
    if (blnValidUser > 0) 
    { 
     // on Success - If remember me > Save to cookies 
     //SaveUserDetailsToCookie();      
    } 
    else 
    { 
     // on Failure - Show error msg 

    } 
} 

Answer 3

IsValidUser返回int這顯然沒有result財產。但我以爲你只是想使用該值：

int valUserResult = IsValidUser(); 
bool blnValidUser = valUserResult == 1; 

但是，你應該考慮在首位返回bool，因爲這將是更具可讀性：

private bool IsValidUser() 
{    
    bool result = false; 
    // ... 
    return result; 
}