使用表达式生成数据集中的自定义列 [英] Generation custom column in dataset with expression
问题描述
在我的示例XML中，对象是ZB。那个ZB有两个点，AAD和AAG。两个点都有共同点，分为|字符。这是一种固定格式，我必须处理它。
因为在我们的软件中，我们使用数据集中的数据。因此，我们使用以下命令将XML转换为数据集：
Dim myDS As DataSet
Dim fsReadXml As 新 System.IO.FileStream（myXMLFile，System.IO.FileMode.Open）
myDS.ReadXml（fsReadXml）
之后，我的数据集中有4个表：
-ZB
-AAE
-AAG
-point
自动添加关系和隐藏ID。之后，我使用此代码连接2个datagrids。一个包含所有对象和第二个网格的数据网格向我显示数据网格1中所选对象的协调：
Dim myBS 作为 新 BindingSource
myBS.DataSource = myDS
DataGridView1.DataSource = myBS
DataGridView1.DataMember = ZB
DataGridView2.DataSource = myBS
DataGridView2.DataMember = ZB.ZB_AAE.AAE_point
到目前为止一切顺利，一切正常！
我单击ZB对象后，可以将标签或其他文本框数据绑定到该点。它的代码如下：
TextBox1.DataBindings.Clear（）
TextBox1.DataBindings.Add（ New 绑定（ text，myBS， ZB.ZB_AAG.AAG_point.pos））
我想要什么？
我想在一个数据网格中使用对象和协作。所以我想创建一个视图，添加一个自定义列，并在一个数据网格中查看XML中的所有字段（AAA，AAD，AAF，AAG）。
我尝试了以下方法。我试过的所有注释行。我无法找到构建表达式的正确方法，因此显示了coördinates：
Dim 测试 As DataColumn = myDS.Tables（ ZB）。Columns.Add（ test， GetType （ String ））
Test.Expression = ZB.ZB_AAE.AAE_point
' Test.Expression =子（ZB.ZB_AAE）.point
' Test.Expression =Child（ZB_AAE） ）.point
' Test.Expression =Child（point）
' Test.Expression =Child（p os）
' Test.Expression =ZB_AAE.point
' Test.Expression =ZB.ZB_AAE.point.pos
< span class =code-comment>' Test.Expression =point
' Test.Expression =point.pos
' Test.Expression =Parent.ZB_AAE.AAE_point.pos
' Test.Expression =父级（ZB_AAE）.AAE_point
Test.Expression =Parent.ZB
' Test.Expression =ZB_AAE.AAE_point.pos
' Test.Expression =Child.ZB_AAE.poin t.pos
您可以使用此XML进行测试：
<？ xml 版本 = 1.0 encoding = ISO-8859-1 standalone = 是 ？ > ;
<！ - 文件标题 - >
< DATA xmlns：nl = http://www.w3.org/2001/XMLSchema-instance xsi：noNamespaceSchemaLocation = file：EN13508 .xsd xmlns：xsi = http://www.w3.org/2001/XMLSchema-instance xmlns：gml = http://www.opengis.net / gml >
< ZB >
< < span class =code-leadattribute> AAA > AAA < / AAA >
< < span class =code-leadattribute> AAD > 1 < / AAD >
< < span class =code-leadattribute> AAE >
< gml：point srsName = Netherlands-RD srsDimension = 2 >
< gml：pos > 123 | 456 < / gml：pos >
< / gml：point >
< / AAE >
< AAF > 2 < / AAF >
< AAG >
< GML：POI nt srsName = Netherlands-RD srsDimension = 2 >
< span class =code-keyword>< gml：pos > 234 | 567 < / gml：pos >
< / gml：point > ;
< / AAG >
< / ZB >
< ZB >
< AAA > AAA < / AAA >
< AAD > 3 < / AAD >
< AAE >
< gml：point srsName = Netherlan ds-RD srsDimension = 2 >
< ; gml：pos > 345 | 678 < / gml：pos >
< / gml：point >
< span class =code-keyword>< / AAE >
< AAF > 4 < span class =code-keyword>< / AAF >
< AAG >
< gml：point srsName = Netherlands-RD srsDimension = 2 >
< gml：pos > 456 | 789 < / gml：pos >
< / gml：point >
< / AAG >
< / ZB >
< < span class =code-leadattribute> / DATA >
In my sample XML the object is "ZB". That "ZB" has two points, "AAD" and "AAG". Both points have coördinates, devided by the "|" character. This is a fixed format, I have to deal with it.
Because in our software, we use the data in a dataset. So we convert the XML tot a dataset with the command:
Dim myDS As DataSet
Dim fsReadXml As New System.IO.FileStream(myXMLFile, System.IO.FileMode.Open)
myDS.ReadXml(fsReadXml)
After that, I have 4 tables in my dataset:
-ZB
-AAE
-AAG
-point
Automaticly there are relations and hidden id's added. After that, I connect 2 datagrids with this code. One datagrid with all objects and the second grid shows me the coördinates of the selected object in datagrid 1:
Dim myBS As New BindingSource
myBS.DataSource = myDS
DataGridView1.DataSource = myBS
DataGridView1.DataMember = "ZB"
DataGridView2.DataSource = myBS
DataGridView2.DataMember = "ZB.ZB_AAE.AAE_point"
So far so good, everything works fine!
I can databind labels or other textboxes to the point, after clicking a "ZB" object. Its with this code:
TextBox1.DataBindings.Clear()
TextBox1.DataBindings.Add(New Binding("text", myBS, "ZB.ZB_AAG.AAG_point.pos"))
What do I want?
I want the objects and coördinates in one datagrid. So I want to create a view, adding a custom column, and see all fields from XML back in one datagrid ("AAA", "AAD", "AAF", "AAG").
I tried the following. All commented lines I tried. I can't find the proper way to build a expression so the coördinates were shown:
Dim Test As DataColumn = myDS.Tables("ZB").Columns.Add("test", GetType(String))
Test.Expression = "ZB.ZB_AAE.AAE_point"
'Test.Expression = "Child(ZB.ZB_AAE).point"
'Test.Expression = "Child(ZB_AAE).point"
'Test.Expression = "Child(point)"
'Test.Expression = "Child(pos)"
'Test.Expression = "ZB_AAE.point"
'Test.Expression = "ZB.ZB_AAE.point.pos"
'Test.Expression = "point"
'Test.Expression = "point.pos"
'Test.Expression = "Parent.ZB_AAE.AAE_point.pos"
'Test.Expression = "Parent(ZB_AAE).AAE_point"
'Test.Expression = "Parent.ZB"
'Test.Expression = "ZB_AAE.AAE_point.pos"
'Test.Expression = "Child.ZB_AAE.point.pos"
You can use this XML to test:
<?xml version="1.0" encoding="ISO-8859-1" standalone="yes"?>
<!-- File Header -->
<DATA xmlns:nl= "http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="file:EN13508.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:gml="http://www.opengis.net/gml">
<ZB>
<AAA>AAA</AAA>
<AAD>1</AAD>
<AAE>
<gml:point srsName="Netherlands-RD" srsDimension="2">
<gml:pos>123|456</gml:pos>
</gml:point>
</AAE>
<AAF>2</AAF>
<AAG>
<gml:point srsName="Netherlands-RD" srsDimension="2">
<gml:pos>234|567</gml:pos>
</gml:point>
</AAG>
</ZB>
<ZB>
<AAA>AAA</AAA>
<AAD>3</AAD>
<AAE>
<gml:point srsName="Netherlands-RD" srsDimension="2">
<gml:pos>345|678</gml:pos>
</gml:point>
</AAE>
<AAF>4</AAF>
<AAG>
<gml:point srsName="Netherlands-RD" srsDimension="2">
<gml:pos>456|789</gml:pos>
</gml:point>
</AAG>
</ZB>
</DATA>这篇关于使用表达式生成数据集中的自定义列的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
