Question

我将一个字段从mysql调用到一个只读textarea，我创建了另一个文本框，允许用户将字段添加到textarea中。如何将文本框中的值组合到textarea？

我想做的一个例子是：

textarea的
15/12：今天没什么特别的
16/12：另一天
17/12：等等

文本框
这是一个新的输入

结果
15/12：今天没什么特别的
16/12：另一天
17/12：等等
18/12：这是一个新的输入

textarea为"log1"，文本框为"txb1"。我目前正在使用

log =  trim(request.form("log1"))

我该怎么做

log = trim(request.form("log1")) <br> date ": " trim(request.form("txb1"))

Answer 1

假设date是一个字符串变量，您可能希望执行以下操作：

log = trim(request.form("log1")) & "<br>" & [date] & ": " & trim(request.form("txb1"))

另外，如果date是DateTime变量，您可能希望使用date.ToShortDateString()而不是<br/>我建议使用Environment.NewLine

甚至更好，你应该使用StringBuilder：

Dim SB As New StringBuilder()
SB.AppendLine(trim(request.form("log1")))
SB.AppendLine([date] & ": " & trim(request.form("txb1")))
log = SB.ToString()

<强>更新

如果要将整个日志存储在一个记录而不是单独的表中，最好将其保存为varbinary(MAX)列中的日志列表。

这是一个如何做的完整示例：

<强> 1。我们首先创建一个<div>元素，它将保存我们的漂亮日志，并由服务器处理，以及一个用于新日志的文本框：

<asp:TextBox ID="txb1" runat="server"></asp:TextBox>
<div id="Text_Div1" runat="server"></div>

<强> 2。现在在后面的代码中，我们创建了一个类来保存1行单行日志：

'create a log class and state that it serializable 
<Serializable> _
Public Class MyLogRecord
    Public Sub New(_msg As String)
        [Date] = DateTime.Now
        Message = _msg
    End Sub
    Public Property [Date]() As DateTime
        Get
            Return m_Date
        End Get
        Set
            m_Date = Value
        End Set
    End Property
    Private m_Date As DateTime
    Public Property Message() As [String]
        Get
            Return m_Message
        End Get
        Set
            m_Message = Value
        End Set
    End Property
    Private m_Message As [String]
    Public Function ToText() As String
        Return [Date].ToShortDateString() & ": " & Convert.ToString(Message)
    End Function
End Class

第3。无论您在何处更新日志，无论是button_click还是textbox_keydown，都可以执行以下操作：

' create a list of logs
Dim MyLogs As List(Of MyLogRecord)
'check if we stored the logs already in the session, 
'if yes, retrieve it from the session var,
'if not then create a new one.
If Session("MyLogs") IsNot Nothing Then
    MyLogs = DirectCast(Session("MyLogs"), List(Of MyLogRecord))
Else
    MyLogs = New List(Of MyLogRecord)()
End If
' create a new log record from the new textbox value
Dim _tempLog As New MyLogRecord(txb1.Text)
'add the new log to the list
MyLogs.Add(_tempLog)
'save it back in a session var:
Session("MyLogs") = MyLogs

<强> 4。在将日志保存到mysql数据库的部分中，您可以这样做：首先将列表转换为字节数组并将其存储在varbinary(MAX)列中

'create a new binary formatter, include System.Runtime.Serialization.Formatters.Binary;
Dim formatter As New BinaryFormatter()
'create a byte array to store our logs list
Dim _logsBinary As Byte()
'create a memory stream to write the logs list into
Using _logStream As New MemoryStream()
    'use the formatter to serialize the list in to an array of bytes 
    'directly into the memory stream
    formatter.Serialize(_logStream, MyLogs)
    'dump the memory stream into the byte array
    _logsBinary = _logStream.ToArray()
End Using
' ... save the _logsBinary into mysql as a 'varbinary(max)' ...

<强> 5。在从mysql数据库中检索日志的位置，您将字节数组反序列化回日志列表：

Dim MyLogs As New List(Of MyLogRecord)()
Dim formatter As New BinaryFormatter()
Using _logStream As New MemoryStream()
    _logStream.Write(_logsBinary, 0, _logsBinary.Length)
    _logStream.Position = 0
    ' de-serialize the byte array back into a logs list
    MyLogs = DirectCast(formatter.Deserialize(_logStream), List(Of MyLogRecord))
End Using

<强> 6。在您在页面中编写日志的位置，您可以这样做：

Dim SB As New StringBuilder()
' create a temp date to compare against all the records,
' and initialize it with the first value or else you will have 
' a orizontal line before the first row
Dim _prevDate As DateTime = MyLogs.First().[Date]
For Each _logRec As MyLogRecord In MyLogs
    'take the date of the currently iterrated item and
    'compare against the temp date, note that comparing months is not enough, 
    'month might be same/earlier but year can be higher
    Dim _currentDate As DateTime = _logRec.[Date]
    If _currentDate.Month > _prevDate.Month OrElse _currentDate.Year > _prevDate.Year Then
        'append horizontal line
        SB.AppendLine("<hr/>")
        'update temp value
        _prevDate = _currentDate
    End If
    'finally append the log: ToText() is the class custom
    'function that we created above
    SB.AppendLine(_logRec.ToText())
Next

'dump the logs into the server managed div:
Text_Div1.InnerHtml = SB.ToString()

合并两个文本框值

1 个答案: