Question

我想使用Next和Previous按钮迭代行数据表。

我的表格如下：

[Ticket Ref]
[Short Description]
[Next Step]
[Last Updated]

通过案例的生命，您可能会获得多个更新。因此，我可能在数据库中有5行与特定Ticket Reference相关。 Comments和Last Updated显然会有所不同。

当表单加载时，它会将数据库中的最后一条记录显示在文本框中，即查询的最后一行。然后，我想点击Previous并查看之前的行。但如果我点击Next我希望它能够循环播放。即转到下一条记录。因此，如果我在记录1上，那么它需要转到2。

我已尝试计算点击次数，但这并非常有用，因为表单首次加载count时会0，如果我点击Previous，那么我会得到Row out of position -1错误。

我之前的按钮如下所示：

    protected void btnPrevious_Click1(object sender, EventArgs e)
    {
        DAL.TicketsDataSetTableAdapters.TicketDetailsTableAdapter eobj = new DAL.TicketsDataSetTableAdapters.TicketDetailsTableAdapter();
        DataTable dt = new DataTable();
        dt = eobj.GetTicketUpdates(txtSupportRef.Text);

        int i = 0;

        if (i < dt.Rows[0].Table.Rows.Count - 1 || i != 0)
        {
            i--;
            txtShortDesc.Text = dt.Rows[0].Table.Rows[i]["ShortDesc"].ToString();
            txtNextStep.Text = dt.Rows[0].Table.Rows[i]["NextStep"].ToString();
            txtLastUpdated.Text = dt.Rows[0].Table.Rows[i]["LastUpdated"].ToString();
        }
        else
        {
            //no records to see more.
        }
    }

我的下一个按钮如下所示：

    protected void btnNext_Click1(object sender, EventArgs e)
    {
        DAL.TicketsDataSetTableAdapters.TicketDetailsTableAdapter eobj = new DAL.TicketsDataSetTableAdapters.TicketDetailsTableAdapter();
        DataTable dt = new DataTable();
        dt = eobj.GetTicketUpdates(txtSupportRef.Text);

        int i = 0;

        if (i < dt.Rows[0].Table.Rows.Count - 1)
        {
            i++;
            txtShortDesc.Text = dt.Rows[0].Table.Rows[i]["ShortDesc"].ToString();
            txtNextStep.Text = dt.Rows[0].Table.Rows[i]["NextStep"].ToString();
            txtLastUpdated.Text = dt.Rows[0].Table.Rows[i]["LastUpdated"].ToString();
        }
        else
        {
            //no records to see more.
        }
    }

此外，用户还可以在表单中加载不同的票证引用。所以我需要能够根据加载的票证快速迭代。

如果您需要更多信息，请询问。

Answer 1

我会在您的数据库表中提供一个索引，然后您可以将其与其余数据一起加载到数据表中。然后，您可以通过基于索引提取行详细信息来使用该索引前进和后退而不用喧嚣：

// store your current row index in a ViewState when first loading the data

ViewState["currentIndex"] = (int)row["RowIndex"];

//When going forward increment your rowIndex to find out the new Row Index
int currentRowIndex = (int) ViewState["currentIndex"];
currentRowIndex++; // ++ to go next -- to go previous

//Get the current row based on rowindex
DataRow row = myDataTable.Select("ID=" + currentRowIndex);
// then use the row data and assign to your textboxes

因此，例如，一个唯一的标识密钥，在数据库表中自动递增1将有助于解决问题。

让我进一步分解：

让我们假设您在页面上获取数据库数据：Load事件：

        protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack) {
             // Code to Fetch database data and assign it to a datatable
             // Save DataTable in a ViewState["currentTable"]
             // Get Last Row and assign field values to textboxes
             // Get Last Row index value and assign it to ViewState["currentRowIndex"]

        }
    }
protected void cmdMoveNext_Click(){
          // in this function you going to get your current row index from the ViewState[currentRowIndex]
       int currentIndex = (int)ViewState["currentRowIndex"];
        currentIndex++; // set next row index (currentIndex=currentIndex+1)
         // declare a datatable and assing viewstate["currentTable"] to it
       DataTable myTable = (DataTable)ViewState["currentTable"];

       // Find the DataRow at the new index
       DataRow row = (DataRow) myTable.Select("search by index code");
       // Use the new row values to assign to textboxes
       // Save the new row index in ViewState


}

Answer 2

如果您正确管理索引环绕，您的解决方案将起作用。

您只需将索引重置为0，当它到达数据集的末尾时，并在从头开始返回时将其设置为DataTable.Rows.Count - 1。

INITIALIZE

 DataTable dt;
 protected override void Page_Load
 {
     // querying each load gets expensive; consider alternative patterns?
     dt = GetData(txtSupportRef.Text);
     if (!IsPostBack)
     {
         int i = 0;
         ViewState["recordIndex"] = i;
         PopulateForm(i);
     }
 }

创造可重复使用的功能 - 他们为您节省了数百美元

protected DataTable GetData(string supportRef)
{
    DAL.TicketsDataSetTableAdapters.TicketDetailsTableAdapter eobj = new DAL.TicketsDataSetTableAdapters.TicketDetailsTableAdapter();
    return eobj.GetTicketUpdates(supportRef);
}
protected void PopulateForm(int i)
{
    ViewState["recordIndex"] = i
    System.Data.DataRow row = dt.Rows[0].Table.Rows[i];
    txtShortDesc.Text = row["ShortDesc"].ToString();
    txtNextStep.Text = row["NextStep"].ToString();
    txtLastUpdated.Text = row["LastUpdated"].ToString();
}

以前的按钮

  protected void btnPrevious_Click1(object sender, EventArgs e)
  {
      int i = (int)ViewState["recordIndex"];
      i = i <= 0 ? dt.Rows[0].Table.Rows.Count - 1 : i-1;
      PopulateForm(i);
  }

下一个按钮

protected void btnNext_Click1(object sender, EventArgs e)
{
      int i = (int)ViewState["recordIndex"];
      i = i >= dt.Rows[0].Table.Rows.Count - 1 ? 0 : i+1;
      PopulateForm(i);
}

这是一个JavaScript示例，它说明了算法，并显示了在执行此客户端时的响应速度。它适用于C＃也

＆＃13;

var startWith = 1; // or 0, etc.
var pageNo = startWith;
var recordCount = 5;
var records = [];
for(var i = 0; i < recordCount; i++)
  {
    records.push({TicketRef: "000-00-"+ i, ShortDescription: ['BLUE SCREEN','VIRUS INFECTION','NEW HARDWARE','SOFTWARE UPGRADE','SPILLED SODA ON KEYBOARD','BROKEN CD-ROM'][Math.random()*6|0], NextStep: ['ESCALATE','RESOLVE','RETURN','CLOSE','INVESTIGATE','TRANSFER'][Math.random()*6|0], LastUpdated: ((Math.random()*12|0)+1).toString() + " hours ago" });
    }
renderPageNo = function() {
  $("h1").text(pageNo);
  $("input:text").each(function(){this.value=records[pageNo-startWith][$(this).data("field")];});
}
prev = function() {
  if (pageNo > startWith) pageNo--
    else pageNo = recordCount;
  renderPageNo(pageNo);
}
next = function() {
  if (pageNo < recordCount) pageNo++
    else pageNo = startWith;
  renderPageNo(pageNo);
}
renderPageNo();
$(".btn").eq(0).on("click", prev).end().eq(1).on("click", next);

＆＃13;

*
{
  font-family: 'Segoe UI';
  }
label
{
  width: 200px;
  display:block;
  }

＆＃13;

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<h1></h1>
<label>Ticket Ref<input type='text' data-field="TicketRef"/></label>
<label>Short Description<input type='text' data-field="ShortDescription"/></label>
<label>Next Step<input type='text' data-field="NextStep"/></label>
<label>LastUpdated<input type='text' data-field="LastUpdated"/></label>
<input class='btn' type='button' value='PREV' />
<input class='btn' type='button' value='NEXT' />

＆＃13;

Answer 3

我做了同样的事情，但更简单，没有使用额外的索引器。

这就是我所做的：

public OnLoad(...)
{
    if(!Page.IsPostBack)
    {
        BuidNavigationList();
    }
    LoadNavigation();
}

private List<string> NavigationList
{
    get
    {
        if (ViewState["NavigationList"] != null)
        {
            return (List<string>)ViewState["NavigationList"];
        }
        return null;
     }
     set
     {
         ViewState["NavigationList"] = value;
     }
}

private void BuidNavigationList()
{
    // ds get

    if (ds.Tables.Count == 1)
    {
        DataTable dataTable = ds.Tables[0];

        if (dataTable.Columns.Contains("YourSwitchColumn"))
        {
            NavigationList = new List<string>(dataTable.Rows.Cast<DataRow>().Select(r => r["YourSwitchColumn"]).Cast<String>());
        }
    }
}

private string YourCurrentSwitchColumnValue
{
    get
    {
        return Request["YourSwitchColumn"].ToString();
    }
}

private void LoadNavigation()
{
     if(this.NavigationList == null)
     {
         lblPrevious.Enabled = false;
         lblNext.Enabled = false;
     }

     int navigationListIndex = NavigationList.IndexOf(YourCurrentSwitchColumnValue);

     if (navigationListIndex == 0)
     {
         lblPrevious.Enabled = false;
         lblNext.Enabled = true;

         lblNext.Value = NavigationList[navigationListIndex + 1];
     }
     else if (navigationListIndex > 0 && navigationListIndex < NavigationList.Count - 1)
     {
         lblPrevious.Enabled = true;
         lblNext.Enabled = true;

         lblPrevious.Value = NavigationList[NavigationListIndex - 1];
         lblNext.Value = NavigationList[NavigationListIndex + 1];                
     }
     else if (navigationListIndex == NavigationList.Count - 1)
     {
         lblPrevious.Enabled = true;
         lblNext.Enabled = false;

         lblPrevious.Value = NavigationList[NavigationListIndex - 1];                
     }
 }

 public void lblNext_OnClick(object sender, ...)
 {
     Request.Redirect("SamePage.aspx?YourSwitchColumn=" + valueFrom_lblNext);
 }

请注意，这是您应根据需要实施的演示代码

使用`Next`和`Previous`按钮遍历行的数据表

3 个答案: