Topic: Linq to XML Selection issue.

[Kerry]

I'm brain dead.
I have an XML file that I'm querying

The file:

Code - XML: [Select]

1. <?xml version="1.0" encoding="utf-8"?>
2. <PRT-data>
3.         <File> "MEMBER"</File>
4.         <member>
5.                 <next_id> "10"</next_id>
6.                 <version> "5.0.0.271"</version>
7.                 <info>
8.                         <item_tag> "test-a6-2"</item_tag>
9.                         <length> "750"</length>
10.                         <mark> "TEST-A6-2"</mark>
11.                         <material> "1"</material>
12.                         <shipping> "1"</shipping>
13.                         <type> "TEST"</type>
14.                 </info>
15.                 <mbr_con>
16.                         <auto_item> "71"</auto_item>
17.                         <con_id> "1"</con_id>
18.                         <name> "WALL PL"</name>
19.                         <connection>
20.                                 <height> "50"</height>
21.                                 <width> "55"</width>
22.                                 <thickness> "10"</thickness>
23.                         </connection>
24.                         <layer>
25.                                 <full> "ST35"</full>
26.                                 <hidden> "STH18"</hidden>
27.                                 <solid> "3dCH-6"</solid>
28.                         </layer>
29.                 </mbr_con>
30.                 <mbr_con>
31.                         <auto_item> "72"</auto_item>
32.                         <con_id> "2"</con_id>
33.                         <name> "WALL PL"</name>
34.                         <connection>
35.                                 <height> "100"</height>
36.                                 <width> "105"</width>
37.                                 <thickness> "10"</thickness>
38.                         </connection>
39.                         <layer>
40.                                 <full> "ST35"</full>
41.                                 <hidden> "STH18"</hidden>
42.                                 <solid> "3dCH-6"</solid>
43.                         </layer>
44.                 </mbr_con>
45.                 <mbr_con>
46.                         <auto_item> "73"</auto_item>
47.                         <con_id> "3"</con_id>
48.                         <name> "WALL PL"</name>
49.                         <connection>
50.                                 <height> "150"</height>
51.                                 <width> "155"</width>
52.                                 <thickness> "10"</thickness>
53.                         </connection>
54.                         <layer>
55.                                 <full> "ST35"</full>
56.                                 <hidden> "STH18"</hidden>
57.                                 <solid> "3dCH-6"</solid>
58.                         </layer>
59.                 </mbr_con>
60.                 <mbr_con>
61.                         <auto_item> "74"</auto_item>
62.                         <con_id> "4"</con_id>
63.                         <name> "WALL PL"</name>
64.                         <connection>
65.                                 <height> "200"</height>
66.                                 <width> "205"</width>
67.                                 <thickness> "10"</thickness>
68.                         </connection>
69.                         <layer>
70.                                 <full> "ST35"</full>
71.                                 <hidden> "STH18"</hidden>
72.                                 <solid> "3dCH-6"</solid>
73.                         </layer>
74.                 </mbr_con>
75.         </member>
76. </PRT-data>
77.  
78.  

The Source :

Code - C#: [Select]

1. using System;
2. using System.Diagnostics;
3. using System.Collections;
4. using System.Collections.Generic;
5. using System.Collections.Specialized;
6. using System.Text;
7. using System.Linq;
8. using System.Xml;
9. using System.Xml.Linq;
10. using System.Xml.Schema;
11. using System.Xml.XPath;
12. using System.Xml.Xsl;
13. using System.IO;
14. using System.Threading;
15. using System.Reflection;
16.  
17.  
18. namespace Read_Write_tsd_stuff
19. {
20.     partial class Program
21.     {
22.         static void Test08()
23.         {
24.             string xmlFile = @"D:\_VSDev\VS2013\TSD-Read-Write\MBRS\TEST-1\M6111-A6-2A.XML";
25.  
26.             XElement  xe = XElement.Load(xmlFile);
27.  
28.             IEnumerable<XElement> allKeys = xe.Elements("member");
29.             // ===================
30.             Console.WriteLine("\n xe0 -----------------------------------");
31.             // Read the entire XML
32.             foreach (var key in allKeys)
33.             {
34.                 Console.WriteLine(key);
35.             }
36.             //// ===================
37.             var xe1 =
38.                 from key in allKeys.Elements("version")
39.                 select key;
40.             foreach (var key in xe1)
41.             {
42.                 Console.WriteLine("\n xe1 -----------------------------------");
43.                 Console.WriteLine(key);
44.                 Console.WriteLine(key.Value);
45.             }
46.             //// ===================
47.             var xe2 =
48.                 from key in allKeys.Descendants("info")
49.                 select key;
50.             foreach (var key in xe2)
51.             {
52.                 Console.WriteLine("\n xe2  -----------------------------------");
53.                 Console.WriteLine(key.Element("mark"));
54.                 Console.WriteLine(key.Element("length"));
55.             }
56.             //// ===================
57.             var xe3 =
58.                 from item in allKeys.Descendants("mbr_con")
59.                 select item;
60.  
61.             Console.WriteLine("\n xe3 -----------------------------------");
62.             Console.WriteLine("mbr_cons Count = {0}", xe3.Count());
63.             foreach (var key in xe3)
64.             {
65.                 Console.WriteLine("-----------------------------------");
66.                 Console.WriteLine("con_id {0} :", key.Element("con_id").Value);
67.                 Console.WriteLine(key);
68.             }
69.             //// ===================
70.             var xe4 =
71.                 from item in xe.Elements("member")
72.                 where (string)item.Element("mbr_con").Element("con_id").Value == "1"
73.                 select item;
74.  
75.             Console.WriteLine(" xe4 -----------------------------------");
76.             Console.WriteLine("mbr_cons Count = {0}", xe4.Count());
77.             foreach (var key in xe4)
78.             {
79.                 Console.WriteLine("-----------------------------------");
80.                 Console.WriteLine("con_id {0} :", key.Element("con_id").Value);
81.                 Console.WriteLine(key);
82.             }
83.             //// ===================
84.  
85.             Console.ReadLine();
86.  
87.         }
88.  
89.     }
90. }
91.  
92.  

The result:

Code - Text: [Select]

1.  
2.  
3.  xe0 -----------------------------------
4. <member>
5.   <next_id> "10"</next_id>
6.   <version> "5.0.0.271"</version>
7.   <info>
8.     <item_tag> "test-a6-2"</item_tag>
9.     <length> "750"</length>
10.     <mark> "TEST-A6-2"</mark>
11.     <material> "1"</material>
12.     <shipping> "1"</shipping>
13.     <type> "TEST"</type>
14.   </info>
15.   <mbr_con>
16.     <auto_item> "71"</auto_item>
17.     <con_id> "1"</con_id>
18.     <name> "WALL PL"</name>
19.     <connection>
20.       <height> "50"</height>
21.       <width> "55"</width>
22.       <thickness> "10"</thickness>
23.     </connection>
24.     <layer>
25.       <full> "ST35"</full>
26.       <hidden> "STH18"</hidden>
27.       <solid> "3dCH-6"</solid>
28.     </layer>
29.   </mbr_con>
30.   <mbr_con>
31.     <auto_item> "72"</auto_item>
32.     <con_id> "2"</con_id>
33.     <name> "WALL PL"</name>
34.     <connection>
35.       <height> "100"</height>
36.       <width> "105"</width>
37.       <thickness> "10"</thickness>
38.     </connection>
39.     <layer>
40.       <full> "ST35"</full>
41.       <hidden> "STH18"</hidden>
42.       <solid> "3dCH-6"</solid>
43.     </layer>
44.   </mbr_con>
45.   <mbr_con>
46.     <auto_item> "73"</auto_item>
47.     <con_id> "3"</con_id>
48.     <name> "WALL PL"</name>
49.     <connection>
50.       <height> "150"</height>
51.       <width> "155"</width>
52.       <thickness> "10"</thickness>
53.     </connection>
54.     <layer>
55.       <full> "ST35"</full>
56.       <hidden> "STH18"</hidden>
57.       <solid> "3dCH-6"</solid>
58.     </layer>
59.   </mbr_con>
60.   <mbr_con>
61.     <auto_item> "74"</auto_item>
62.     <con_id> "4"</con_id>
63.     <name> "WALL PL"</name>
64.     <connection>
65.       <height> "200"</height>
66.       <width> "205"</width>
67.       <thickness> "10"</thickness>
68.     </connection>
69.     <layer>
70.       <full> "ST35"</full>
71.       <hidden> "STH18"</hidden>
72.       <solid> "3dCH-6"</solid>
73.     </layer>
74.   </mbr_con>
75. </member>
76.  
77.  xe1 -----------------------------------
78. <version> "5.0.0.271"</version>
79.  "5.0.0.271"
80.  
81.  xe2  -----------------------------------
82. <mark> "TEST-A6-2"</mark>
83. <length> "750"</length>
84.  
85.  xe3 -----------------------------------
86. mbr_cons Count = 4
87. -----------------------------------
88. con_id  "1" :
89. <mbr_con>
90.   <auto_item> "71"</auto_item>
91.   <con_id> "1"</con_id>
92.   <name> "WALL PL"</name>
93.   <connection>
94.     <height> "50"</height>
95.     <width> "55"</width>
96.     <thickness> "10"</thickness>
97.   </connection>
98.   <layer>
99.     <full> "ST35"</full>
100.     <hidden> "STH18"</hidden>
101.     <solid> "3dCH-6"</solid>
102.   </layer>
103. </mbr_con>
104. -----------------------------------
105. con_id  "2" :
106. <mbr_con>
107.   <auto_item> "72"</auto_item>
108.   <con_id> "2"</con_id>
109.   <name> "WALL PL"</name>
110.   <connection>
111.     <height> "100"</height>
112.     <width> "105"</width>
113.     <thickness> "10"</thickness>
114.   </connection>
115.   <layer>
116.     <full> "ST35"</full>
117.     <hidden> "STH18"</hidden>
118.     <solid> "3dCH-6"</solid>
119.   </layer>
120. </mbr_con>
121. -----------------------------------
122. con_id  "3" :
123. <mbr_con>
124.   <auto_item> "73"</auto_item>
125.   <con_id> "3"</con_id>
126.   <name> "WALL PL"</name>
127.   <connection>
128.     <height> "150"</height>
129.     <width> "155"</width>
130.     <thickness> "10"</thickness>
131.   </connection>
132.   <layer>
133.     <full> "ST35"</full>
134.     <hidden> "STH18"</hidden>
135.     <solid> "3dCH-6"</solid>
136.   </layer>
137. </mbr_con>
138. -----------------------------------
139. con_id  "4" :
140. <mbr_con>
141.   <auto_item> "74"</auto_item>
142.   <con_id> "4"</con_id>
143.   <name> "WALL PL"</name>
144.   <connection>
145.     <height> "200"</height>
146.     <width> "205"</width>
147.     <thickness> "10"</thickness>
148.   </connection>
149.   <layer>
150.     <full> "ST35"</full>
151.     <hidden> "STH18"</hidden>
152.     <solid> "3dCH-6"</solid>
153.   </layer>
154. </mbr_con>
155.  xe4 -----------------------------------
156. mbr_cons Count = 0
157.  
158.  
159.  

The problem : perhaps misguided expectations

I expected the result for xe4 to be the same as the first part of xe3 ; that is return ONLY the block(s) which contain a "con_id" of "1"
and I expected the collection count to be 1.

This is a learning exercise and not time critical ... just trying to fit it into a bit of spare time I've made.
Anyone got any ideas regarding where I've gone wrong. I haven't researched this as well as I'd like.

[Jeff H]

Going to post a project a little later, but Element gets first child with name, and in ConsoleWriteLine uses Element again so looking for child element "con_id" in "con_id".

[MexicanCustard]

Code - C#: [Select]

1.  var xe4 =
2.                 from item in xe.Elements("member")
3.                 where (string)item.Element("mbr_con").Element("con_id").Value == "1"
4.                 select item;

item.Element() is returning an IEnumerable so this statement isn't legal. I see now that you were calling Element() not Elements(). So from a quick glance not sure why you're not getting the result you expected.

Try something like this.

Code - C#: [Select]

1.  var xe4 =
2.                 from item in xe.Elements("member")
3.                 let mbrs = item.Elements("mbr_con")
4.                 from mbr in mbrs
5.                 let conIds = mbr.Elements("con_id")
6.                 from id in conIds
7.                 where id.Value == "1"
8.                 select item;

*EDIT*: Forgot the con_id element

[Jeff H]

Code - C#: [Select]

1.             Console.WriteLine(" xe4 -----------------------------------");
2.             Console.WriteLine("mbr_cons Count = {0}", xe4.Count());
3.             foreach (var key in xe4)
4.             {
5.                 Console.WriteLine("-----------------------------------");
6.                 Console.WriteLine("con_id {0} :", key.Element("con_id").Value);
7.                 Console.WriteLine(key);
8.             }
9.  
10.  

As mentioned previously it looking another child named "con_id" when key.Element("con_id")

[Kerry]

< .. >

Try something like this.

Code - C#: [Select]

1.  var xe4 =
2.                 from item in xe.Elements("member")
3.                 let mbrs = item.Elements("mbr_con")
4.                 from mbr in mbrs
5.                 let conIds = mbr.Elements("con_id")
6.                 from id in conIds
7.                 where id.Value == "1"
8.                 select item;

Thanks for the responses guys.
I tried several variations on that ... the IEnumerable xe4 is still null so the count is still 0

This is very frustrating. I'll have another play tonight.

Code - C#: [Select]

1.  
2.             //// ===================
3.             var xe4 =
4.                 from con in allKeys.Descendants("mbr_con")
5.                 let conIds = con.Elements("con_id")
6.                 from id in conIds
7.                 where id.Value == "1"
8.                 select con;
9.  
10.                 //from item in xe.Elements("member")
11.                 //let mbrs = item.Elements("mbr_con")
12.                 //from mbr in mbrs
13.                 //let conIds = mbr.Elements("con_id")
14.                 //from id in conIds
15.                 //where id.Value == "1"
16.                 //select item;
17.  
18.             Console.WriteLine(" xe4 -----------------------------------");
19.             Console.WriteLine("con_id Count = {0}", xe4.Count());
20.             foreach (var key in xe4)
21.             {
22.                 Console.WriteLine("-----------------------------------");
23.                 Console.WriteLine("con_id {0} :", key.Element("con_id").Value);
24.                 Console.WriteLine(key);
25.             }
26.             //// ===================
27.  

[Jeff H]

Little tied down but got project set up with unit tests. Nothing new to you but for anyone else who has never used them might help.
Will post later.

[Kerry]

Thanks Jeff. That sounds Great.
As you know LINQ stuff is not easy to debug and step through.

The XML is fashioned manually for simplicity. The original XML is a bit over 3000 lines long and is being created programmatically from a raw text file with a proprietary format .. at least I have that part working to my satisfaction

[Kerry]

This failed also

Code - C#: [Select]

1.  
2.             var xe4 =
3.                 from c in xe.Elements("member")
4.                 where (from n in c.Elements("mbr_con") where            
5.                            (string)n.Element("con_id") == "1" select n).Any()  
6.                 select c;
7.  

[Jeff H]

It's that space that got me, but working on this machine

Code - C#: [Select]

1.             var xe4 =
2.                 xe.Descendants("con_id")
3.                 .Where(d => d.Value == " \"1\"");
4.  

or

Code - C#: [Select]

1.              var xe4 = xe.Elements("member")
2.                  .Elements("mbr_con")
3.                  .Where(ele => ele.Element("con_id").Value == " \"1\"");
4.  

[Kerry]

Thanks Jeff .. brilliant.

I edited the xml to remove the space and this worked.

Code - C#: [Select]

1.             var xe4 =                
2.                  allKeys
3.                  .Elements("mbr_con")
4.                  .Where(ele => ele.Element("con_id").Value == "\"1\"");
5.  

When I wrote the parser I ignored that the values were automatically strings. duh!

When I modified the XML so the values weren't quoted this worked.
ie the xml is now :

Code - XML: [Select]

1.                 <mbr_con>
2.                         <auto_item>71</auto_item>
3.                         <con_id>1</con_id>
4.                         <name>WALL PL</name>
5.                         <connection>
6.                                 <height>50</height>
7.                                 <width>55</width>
8.                                 <thickness>10</thickness>
9.                         </connection>
10.                         <layer>
11.                                 <full>ST35</full>
12.                                 <hidden>STH18</hidden>
13.                                 <solid>3dCH-6</solid>
14.                         </layer>
15.                 </mbr_con>
16.  

So this works.

Code - C#: [Select]

1.             var xe4 =                
2.                  allKeys
3.                  .Elements("mbr_con")
4.                  .Where(ele => ele.Element("con_id").Value == "1");
5.  

I'll revise the translation parser tonight and see how that goes.

Thanks for the eyes and the effort Jeff, appreciated muchly.

[MickD]

Hi Kerry,
I was playing around with this using XPath and the quoted numbers (i.e. "1") were giving me all sorts of trouble, removed the quotes and all was easy, code below for shiggles.

edit: in fact I think you are supposed to only use mark up for things like quotes etc. eg. &quot; for " and the quotes are not required for strings in general.
edit2: doh, I see you already worked that out

Code - C#: [Select]

1.         static void Main()
2.         {
3.             XmlDocument xmlDoc = new XmlDocument();
4.             xmlDoc.Load(@"C:\00-Job folders\Temp stuff\KWB_data.XML");
5.  
6.             XmlNamespaceManager nsMgr = new XmlNamespaceManager(xmlDoc.NameTable);
7.            
8.  
9.             XmlNodeList selectedNodes = xmlDoc.SelectNodes("/PRT-data/member/mbr_con[con_id = \"1\"]", nsMgr);
10.             Console.WriteLine("mbr_cons Count = {0}", selectedNodes.Count);
11.            
12.             foreach (XmlNode selectedNode in selectedNodes)
13.             {
14.                     Console.WriteLine("-----------------------------------");
15.                     XmlNodeList childNodes = selectedNode.ChildNodes;
16.                     foreach (XmlNode node in childNodes)
17.                     {
18.                         Console.WriteLine("Node {0} : \n", node.Name);
19.  
20.                         // if it has more child nodes, print them out:
21.                         if(node.HasChildNodes)
22.                         {
23.                             XmlNodeList childNodes1 = node.ChildNodes;
24.                             foreach(XmlNode n in childNodes1)
25.                             {
26.                                 Console.WriteLine("     {0} : {1} \n", n.Name, n.InnerText);
27.                             }
28.                         }
29.                     }
30.             }
31.  
32.             Console.ReadLine();
33.  
34.         }

[Kerry]

Thanks Mick.

The xml generator is currently using  writer.WriteElementString(key, value) which forces the value to be a quoted string.
which gives me
<title>"Value"</title>

I'll probably change it to a 3 step process per Element
writer.WriteStartElement("title");
writer.WriteString("Value");
writer.WriteEndElement();

which will give me something like
<title>Value</title>

... or I may write the data as Attributes, haven't decided yet.

I'm learning this stuff so I'm just concentrating on getting ducks in a row.

The ultimate goal is to read the data files, translate to XML for perusing in a dataGridView and possible edits then write back to the original format. The XML is really just a means to an end rather than the finished product.

Because of this I have the option to change the interim data format as I see fit.

[fixo]

This little code snip is working on my end:

Code: [Select]

         XElement root = XElement.Load(@"C:\Test\STL.xml");
       
            var items = (from n in root.Descendants("mbr_con").Elements("con_id") select n.Name + "=" + n.Value).ToArray();
            foreach (var a in items)
                Console.WriteLine(a);

[Kerry]

Thanks Oleg.
That is an interesting variation !

[MexicanCustard]

If you know the XML format and its always the same, why not Serialize it?  That would be a lot easier than looping through writing/reading every value.