VB.NET项目技术总结
VB.NET是微软asp之后、ASP.NET之前的Web开发技术。
前台页面的拓展名是.aspx,后端扩展名是.vb，前台aspx页面继承自.aspx.vb，aspx页面基本上和asp.net中aspx页面一模一样，主要就是服务器控件都是一样的，Grid的Eval绑定表达式都是一样的。
后端的VB和C#语法还是有一定区别的， 写惯了C#,觉得vb语法不优雅
1. 基本语法：
Dim sort As String
Protected Sub BindLines()
dropLines.DataSource = viewCurrentCountsBL.GetLines()
dropLines.DataTextField = "DESCRIPTION"
dropLines.DataValueField = "LINE_ID"
dropLines.DataBind()
End Sub
Protected Function GetIco(itemType As String) As String
If itemType = "1" Then
Return "<img src='/images/tool.png'/>"
ElseIf itemType = "2" Then
Return "<img src='/images/Kits.png'/>"
Else
Return ""
End If
End Function
Protected Sub chkHideTools_CheckedChanged(sender As Object, e As EventArgs) Handles chkHideTools.CheckedChanged
BindGird()
End Sub
其中，跟C#中一些关键字差异的地方：Dim申明值类型、类变量，As 类型。Sub/End Sub,If/End If 相当于C#中If{},void Fun(){}
C#中a!=null, vb中a Is Nothing
C# ！布尔值变量、表达式写法位!flag、!IsValid(), vb中Not flag、 not IsValid()
2. VB.NET中的GridView Sorting
2.1.利用table.DefaultView.Sort='SortExpression sortDirection'
Protected Sub GridView1_Sorting(sender As Object, e As GridViewSortEventArgs) Handles GridView1.Sorting
Dim table = Session("ViewCurrentCountGridData")
Dim sortDirection As String
Dim sort As String
If table Is Nothing Then
If Request.QueryString("operationIds") IsNot Nothing AndAlso Not String.IsNullOrEmpty(Request.QueryString("operationIds").ToString()) Then
Dim operationIds As New System.Collections.ObjectModel.Collection(Of Long)
table = viewCurrentCountsBL.GetItemsForOps(operationIds, chkHideTools.Checked)
Session("ViewCurrentCountGridData") = table
Else
table = viewCurrentCountsBL.GetItems(Long.Parse(dropLines.SelectedValue), 0, chkHideTools.Checked)
Session("ViewCurrentCountGridData") = table
End If
End If
If String.IsNullOrEmpty(e.SortExpression) Then
sort = "last_update desc"
Else
If ViewState("SortDirection") IsNot Nothing AndAlso ViewState("SortDirection").ToString() = "asc" Then
sortDirection = "desc"
Else
sortDirection = "asc"
End If
sort = e.SortExpression + " " + sortDirection
ViewState("SortDirection") = sortDirection
End If
table.DefaultView.Sort = sort
GridView1.DataSource = table.DefaultView
GridView1.DataBind()
End Sub
2.2 用DataTable.Select(filterExpression, sortStr) ，下面的4中有示例代码。
3. Decimal取14位：
Math.Round(Decimal.Parse(hours.ToString()),14)
4. 实现下图效果：
如果是按照Hours Remaining排序的时候，根据Hours Remaining值的范围2以下，2-4，4-6，6-8，8-10，10以上，"分组"显示，显示组标题。
4.1. 后台计算得出规律，生成json字符串，在前台解析，通过JS添加tr
Protected Sub GridView1_Sorting(sender As Object, e As GridViewSortEventArgs) Handles GridView1.Sorting
Dim table = Session("ViewCurrentCountGridData")
Dim sortDirection As String
Dim sort As String
Dim filter = String.Format("hours<={0}", hoursUnder)
If table Is Nothing Then
table = GetData()
Session("ViewCurrentCountGridData") = table
End If
If String.IsNullOrEmpty(e.SortExpression) Then
sort = "last_update desc"
Else
If ViewState("SortDirection") IsNot Nothing AndAlso ViewState("SortDirection").ToString() = "asc" Then
sortDirection = "desc"
Else
sortDirection = "asc"
End If
sort = e.SortExpression + " " + sortDirection
ViewState("SortField") = e.SortExpression
ViewState("SortDirection") = sortDirection
End If
GridView1.DataSource = table.Select(filter, sort)
GridView1.DataBind()
If e.SortExpression.ToLower() = "hours" Then
SetUnderHours(table)
End If
End Sub
Protected Sub SetUnderHours(table As DataTable)
Dim listHours = (
From item In table.AsEnumerable() Where Not item.IsNull("hours")
Select item.Field(Of Decimal)("hours")
).ToList().Where(Function(m) m <= hoursUnder).ToList()
Dim query2 = From el In listHours Group el By key = GetUnderKey(el) Into g = Group _
Select New With { _
.Key = key, _
.min = g.Min(),
.max = g.Max()
}
Dim list = query2.ToList()
If list IsNot Nothing Then
json = "["
For i As Integer = 0 To list.Count - 1
If i = list.Count - 1 Then
json += "{'underKey':" + list(i).Key.ToString() + ",'min':" + list(i).min.ToString() + ",'max':" + list(i).max.ToString() + "}"
Else
json += "{'underKey':" + list(i).Key.ToString() + ",'min':" + list(i).min.ToString() + ",'max':" + list(i).max.ToString() + "},"
End If
Next
json += "]"
End If
End Sub
Public Function GetUnderKey(hours As Decimal) As Integer
If hours <= 0 Then
Return -1
ElseIf 0 < hours And hours <= 2 Then
Return 2
ElseIf 2 < hours And hours <= 4 Then
Return 4
ElseIf 4 < hours And hours <= 6 Then
Return 6
ElseIf 6 < hours And hours <= 8 Then
Return 8
ElseIf 8 < hours And hours <= 10 Then
Return 10
ElseIf hours > 10 Then
Return 11
Else
Return -1
End If
End Function
<script type="text/javascript">
$(function () {
var jsonStr = eval("<%=json%>");
var sortField = "<%=ViewState("SortField")%>";
var sortDirection="<%=ViewState("SortDirection")%>";
if (sortField.toLowerCase() == "hours") {
$.each(jsonStr, function (i, item) {
if (sortDirection == "desc") {
var maxRow = $("#<%=GridView1.ClientID %> tr input[data-field='hours'][value='" + item.max.toFixed(14) + "']").eq(0).parent().parent();
var title = item.underKey == 11 ? "Over 10 Hours" : "Under " + item.underKey + " Hours";
maxRow.before($("<tr><td style='background-color:blue;color:white'>" + title + " </td><td colspan='5'></td></tr>"));
}
else {
var minRow = $("#<%=GridView1.ClientID %> tr input[data-field='hours'][value='" + item.min.toFixed(14) + "']").eq(0).parent().parent();
var title = item.underKey == 11 ? "Over 10 Hours" : "Under " + item.underKey + " Hours";
minRow.before($("<tr><td style='background-color:blue;color:white'>" + title + " </td><td colspan='5'></td></tr>"));
}
});
}
});
</script>
其中的难点：1.思路 2.vb的linq语法，特别根据列值，得出计算值再分组，不太好弄。
4.2 用C# linq 实现的group，返回json的代码如下：
4.3 在服务端插入group row，代码如下：
