Filter result using linq

Question

0.00/5 (No votes)

See more:

What is wrong in this linq query, it is showing error? "Object reference not set to an instance of an object."

C#

String  StoreNumber="1259";

XElement xel = xDoc.Element("Items")
                           .Elements("Item")
                           .Where(x => x.Elements("StoreNumber").SingleOrDefault().Value == StoreNumber.Trim())
                           .SingleOrDefault();

XDocumnet is

XML

<Items>
   <Item>
    <ItemID>426</ItemID>
    <Name>1064</Name>
    <ParentID>307</ParentID>
    <DisplayName><![CDATA[1064]]></DisplayName>
    <ChildViewLayout>Store</ChildViewLayout>
    <Keywords><![CDATA[1064;]]></Keywords>
    <StoreNumber>1064</StoreNumber>
    <StoreFloor>AAHOA</StoreFloor>
    <PathFile>Entrance.txt;1000-Right.txt;1064-R.txt</PathFile>
  </Item>
  <Item>
    <ItemID>427</ItemID>
    <Name>1066</Name>
    <ParentID>307</ParentID>
    <DisplayName><![CDATA[1066]]></DisplayName>
    <ChildViewLayout>Store</ChildViewLayout>
    <Keywords><![CDATA[1066;]]></Keywords>
    <StoreNumber>1066</StoreNumber>
    <StoreFloor>AAHOA</StoreFloor>
    <PathFile>Entrance.txt;1000-Right.txt;1066-R.txt</PathFile>
  </Item>
  <Item>
    <ItemID>428</ItemID>
    <Name>1259</Name>
    <ParentID>309</ParentID>
    <DisplayName><![CDATA[1259]]></DisplayName>
    <ChildViewLayout>Store</ChildViewLayout>
    <Keywords><![CDATA[1259;]]></Keywords>
    <StoreNumber>1259</StoreNumber>
    <StoreFloor>AAHOA</StoreFloor>
    <PathFile>Entrance.txt;1101-Right.txt;1259-L.txt</PathFile>
  </Item>
  <Item>
    <ItemID>429</ItemID>
    <Name>1271</Name>
    <ParentID>309</ParentID>
    <DisplayName><![CDATA[1271]]></DisplayName>
    <ChildViewLayout>Store</ChildViewLayout>
    <Keywords><![CDATA[1271;]]></Keywords>
    <StoreNumber>1271</StoreNumber>
    <StoreFloor>AAHOA</StoreFloor>
    <PathFile>Entrance.txt;1101-Right.txt;1271-L.txt</PathFile>
  </Item>
  <Item>
    <ItemID>430</ItemID>
    <Name>Fire-Exit</Name>
    <ParentID>4</ParentID>
    <DisplayName><![CDATA[Fire Exit]]></DisplayName>
    <ItemImage>utils-fireexit.png</ItemImage>
    <ChildViewLayout>Utilities</ChildViewLayout>
    <StoreFloor>AAHOA</StoreFloor>
    <PathFile>Fire-Exit.txt</PathFile>
  </Item>
  <Item>
    <ItemID>431</ItemID>
    <Name>Rest-Room</Name>
    <ParentID>4</ParentID>
    <DisplayName><![CDATA[Rest Room]]></DisplayName>
    <ItemImage>utils-restroom.png</ItemImage>
    <ChildViewLayout>Utilities</ChildViewLayout>
    <StoreFloor>AAHOA</StoreFloor>
    <PathFile>Rest-Room.txt</PathFile>
  </Item>
  <Item>
    <ItemID>432</ItemID>
    <Name>Disabled-Rest-Room</Name>
    <ParentID>4</ParentID>
    <DisplayName><![CDATA[Disabled Rest Room]]></DisplayName>
    <ItemImage>utils-handicap.png</ItemImage>
    <ChildViewLayout>Utilities</ChildViewLayout>
    <StoreFloor>AAHOA</StoreFloor>
    <PathFile>Handicap-Rest-Room.txt</PathFile>
  </Item>
  <Item>
    <ItemID>433</ItemID>
    <Name>Management Office</Name>
    <ParentID>4</ParentID>
    <DisplayName><![CDATA[Management Office]]></DisplayName>
    <ChildViewLayout>Utilities</ChildViewLayout>
    <StoreFloor>AAHOA</StoreFloor>
    <PathFile>Management-Office.txt</PathFile>
  </Item>
  <Item>
    <ItemID>434</ItemID>
    <Name>Conference Hall</Name>
    <ParentID>4</ParentID>
    <DisplayName><![CDATA[Conference Hall]]></DisplayName>
    <ChildViewLayout>Utilities</ChildViewLayout>
    <StoreFloor>AAHOA</StoreFloor>
    <PathFile>Conference-Hall.txt</PathFile>
  </Item>
  <Item>
    <ItemID>435</ItemID>
    <Name>Offers</Name>
    <ParentID>0</ParentID>
    <DisplayName><![CDATA[Offers]]></DisplayName>
    <ItemImage>Offers.png</ItemImage>
    <ChildViewLayout>Button</ChildViewLayout>
  </Item>
  <Item>
    <ItemID>436</ItemID>
    <Name>For members</Name>
    <ParentID>435</ParentID>
    <DisplayName><![CDATA[For members]]></DisplayName>
    <ChildViewLayout>Offers</ChildViewLayout>
    <Tag>PromotionDataMembers</Tag>
  </Item>
  <Item>
    <ItemID>437</ItemID>
    <Name>For non members</Name>
    <ParentID>435</ParentID>
    <DisplayName><![CDATA[For non members]]></DisplayName>
    <ChildViewLayout>Offers</ChildViewLayout>
    <Tag>PromotionDataNonMembers</Tag>
  </Item>
</Items>

Posted 20-Feb-14 20:38pm

AVNISHmishra

Updated 20-Feb-14 20:45pm

v3

Add a Solution

Comments

Kornfeld Eliyahu Peter 21-Feb-14 2:40am

What xDoc is? Where you initiate it?

AVNISHmishra 21-Feb-14 2:43am

i have given xDoc below the question

AVNISHmishra 21-Feb-14 2:45am

XDocument xDoc = here i set xDocument that given in question

AVNISHmishra 21-Feb-14 2:51am

if i use

.Where(x => x.Element("StoreNumber").Value == StoreNumber.Trim()

istead of
.Where(x => x.Elements("StoreNumber").SingleOrDefault().Value == StoreNumber.Trim()

then its also not working, same error

because element keyword search only first element

AVNISHmishra 21-Feb-14 2:53am

if i use

.Where(x => x.Element("ItemID").Value == itemID.Trim()

then its working fine, but i want search based on storeNumber

3 solutions

Solution 3

This works for me with your xml content. Sry it's in VB.NET

VB

Dim stringContent = "<items><item><itemid>426</itemid><name>1064</name><parentid>307</parentid><displayname><![CDATA[1064</displayname><childviewlayout>Store</childviewlayout><keywords><![CDATA[1064;</keywords><storenumber>1064</storenumber><storefloor>AAHOA</storefloor><pathfile>Entrance.txt;1000-Right.txt;1064-R.txt</pathfile></item><item><itemid>427</itemid><name>1066</name><parentid>307</parentid><displayname><![CDATA[1066</displayname><childviewlayout>Store</childviewlayout><keywords><![CDATA[1066;</keywords><storenumber>1066</storenumber><storefloor>AAHOA</storefloor><pathfile>Entrance.txt;1000-Right.txt;1066-R.txt</pathfile></item><item><itemid>428</itemid><name>1259</name><parentid>309</parentid><displayname><![CDATA[1259</displayname><childviewlayout>Store</childviewlayout><keywords><![CDATA[1259;</keywords><storenumber>1259</storenumber><storefloor>AAHOA</storefloor><pathfile>Entrance.txt;1101-Right.txt;1259-L.txt</pathfile></item><item><itemid>429</itemid><name>1271</name><parentid>309</parentid><displayname><![CDATA[1271</displayname><childviewlayout>Store</childviewlayout><keywords><![CDATA[1271;</keywords><storenumber>1271</storenumber><storefloor>AAHOA</storefloor><pathfile>Entrance.txt;1101-Right.txt;1271-L.txt</pathfile></item><item><itemid>430</itemid><name>Fire-Exit</name><parentid>4</parentid><displayname><![CDATA[FireExit</displayname><itemimage>utils-fireexit.png</itemimage><childviewlayout>Utilities</childviewlayout><storefloor>AAHOA</storefloor><pathfile>Fire-Exit.txt</pathfile></item><item><itemid>431</itemid><name>Rest-Room</name><parentid>4</parentid><displayname><![CDATA[RestRoom</displayname><itemimage>utils-restroom.png</itemimage><childviewlayout>Utilities</childviewlayout><storefloor>AAHOA</storefloor><pathfile>Rest-Room.txt</pathfile></item><item><itemid>432</itemid><name>Disabled-Rest-Room</name><parentid>4</parentid><displayname><![CDATA[DisabledRestRoom</displayname><itemimage>utils-handicap.png</itemimage><childviewlayout>Utilities</childviewlayout><storefloor>AAHOA</storefloor><pathfile>Handicap-Rest-Room.txt</pathfile></item><item><itemid>433</itemid><name>ManagementOffice</name><parentid>4</parentid><displayname><![CDATA[ManagementOffice</displayname><childviewlayout>Utilities</childviewlayout><storefloor>AAHOA</storefloor><pathfile>Management-Office.txt</pathfile></item><item><itemid>434</itemid><name>ConferenceHall</name><parentid>4</parentid><displayname><![CDATA[ConferenceHall</displayname><childviewlayout>Utilities</childviewlayout><storefloor>AAHOA</storefloor><pathfile>Conference-Hall.txt</pathfile></item><item><itemid>435</itemid><name>Offers</name><parentid>0</parentid><displayname><![CDATA[Offers</displayname><itemimage>Offers.png</itemimage><childviewlayout>Button</childviewlayout></item><item><itemid>436</itemid><name>Formembers</name><parentid>435</parentid><displayname><![CDATA[Formembers</displayname><childviewlayout>Offers</childviewlayout><tag>PromotionDataMembers</tag></item><item><itemid>437</itemid><name>Fornonmembers</name><parentid>435</parentid><displayname><![CDATA[Fornonmembers</displayname><childviewlayout>Offers</childviewlayout><tag>PromotionDataNonMembers</tag></item></items>"
Dim storeNumber = "1259"

Dim xDoc = XDocument.Parse(stringContent)

Dim someItems = From x in xDoc.Descendants("Item") Where x.Element("StoreNumber") = storeNumber
For Each item in someItems
    Console.WriteLine(item.ToString)
Next

Dim singleItem = xDoc.Descendants("Item").Single(Function(x) x.Element("StoreNumber") = storeNumber)
Console.WriteLine(singleItem.ToString)

Posted 20-Feb-14 21:30pm

pjaar89

v2

Solution 2

Hi I m sure the problem is SingleOrDefault()! use FirstOrDefault() instead.

WHen using SingleOrDefault, you have to be 100% sure that each element is unique, if not an exception occure. in the other hand FirstOrDefault() returns the first element if there is duplicates.

Hope it helps

Posted 20-Feb-14 21:26pm

Ziee-M

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Kornfeld Eliyahu Peter · Accepted Answer · 2014-02-20T21:19:00

Solution 1

The problem is that not all your elements has StoreNumber node!

Posted 20-Feb-14 21:19pm

Kornfeld Eliyahu Peter

Comments

AVNISHmishra 21-Feb-14 4:16am

Yes but what will i do to check !=null

AVNISHmishra 21-Feb-14 4:23am

Thank you brother, this is the answer

XElement xel = xDoc.Element("Items")
.Elements("Item")
.Where(x => x.Element("StoreNumber") !=null)
.Where(x => x.Element("StoreNumber").Value == StoreNumber.Trim())
.SingleOrDefault();