XPath select node by node, subnode and subsubnode condition

Question

I would like to retrieve all nodes with a node, subnode and subsubnode condition applied

I tried to receive it with this xpath command:

xmlDoc.SelectNodes("//WorkItem[WorkItemType[text()='Product Backlog Item'] and ./Childern/WorkItem/WorkItemType[text() = 'Task'] and /Childern/WorkItem/WorkItemType[text() != 'Product Backlog Item'] and ./Childern/WorkItem/WorkItemType[text() = 'Task']]");

This provides me no nodes. But I expect the WorkItem nodes with Id's: 719 and 720 but NOT 717

How can I express this in XPath?

The given xml looks like this:

<?xml version="1.0" encoding="utf-8"?>
<root>
    <id>716</id>
    <WorkItemType>Product Backlog Item</WorkItemType>
    <Children>
        <WorkItem>
            <id>717</id>
            <WorkItemType>Product Backlog Item</WorkItemType>
            <Children>
                <WorkItem>
                    <id>719</id>
                    <WorkItemType>Product Backlog Item</WorkItemType>
                    <Children>
                        <WorkItem>
                            <id>721</id>
                            <WorkItemType>Task</WorkItemType>
                            <Children>
                                <WorkItem>
                                    <id>722</id>
                                    <WorkItemType>Task</WorkItemType>
                                    <Children/>
                                </WorkItem>
                            </Children>
                        </WorkItem>
                    </Children>
                </WorkItem>
                <WorkItem>
                    <id>720</id>
                    <WorkItemType>Product Backlog Item</WorkItemType>
                    <TreeLevel>2</TreeLevel>
                    <Children>
                        <WorkItem>
                            <id>724</id>
                            <WorkItemType>Task</WorkItemType>
                            <Children>
                                <WorkItem>
                                    <id>726</id>
                                    <WorkItemType>Task</WorkItemType>
                                    <Children/>
                                </WorkItem>
                            </Children>
                        </WorkItem>
                    </Children>
                </WorkItem>
                <WorkItem>
                    <id>723</id>
                    <WorkItemType>Task</WorkItemType>
                    <Children>
                        <WorkItem>
                            <id>744</id>
                            <WorkItemType>Task</WorkItemType>
                            <Children/>
                        </WorkItem>
                    </Children>
                </WorkItem>
            </Children>
        </WorkItem>
    </Children>
</root>

Update

Due to Rolf Rander's input I add some more explanation:

• I want to have WorkItem-elements of WorkItemType 'Product Backlog Item' which has ONLY WorkItem-Elements of WorkItemType 'Task' as any kind of children (children, grandchildren grandgrandchildren and so on...).

The level how deep are children capsuled is not clear at design time. I've updated my question. (and I corrected my typo Childern -> Children in the xml file).

Answer 1

It is not completely clear what you try to achieve, but reformatting your code it seems you have several reduntant tests:

//WorkItem[
WorkItemType[text()='Product Backlog Item'] and
./Childern/WorkItem/WorkItemType[text() = 'Task'] and
/Childern/WorkItem/WorkItemType[text() != 'Product Backlog Item'] and
./Childern/WorkItem/WorkItemType[text() = 'Task']
]

You test for "equal to 'Task'" twice, and it shouldn't be neccessary to both check that it is equal to 'Task' and different from 'Product Backlog Item'.

You can check for "any children or grandchildren" with //, thus:

• Any WorkItem
• with WorkItemType = 'Product Backlog Item', and
• no nodes under Children with name WorkItemType and contents 'Task'

can be translated to:

//WorkItem[
     WorkItemType[text()='Product Backlog Item'] and
     not(Children//WorkItemType[text() != 'Task'])
]

Answer 2

Instead of this..

./Childern/WorkItem/WorkItemType[text() != 'Product Backlog Item']

use this one :

not(./Childern/WorkItem/WorkItemType[text() = 'Product Backlog Item'])

The former evaluates to true if there is at least one WorkItemType match the criteria (has the first text node child not equals to 'Product Backlog Item'). Contrast it with the latter which evaluates to true only when there is no WorkItemType match the criteria (has the first text node child equals to 'Product Backlog Item').

So the complete XPath would look like this (formatted for readability) :

//WorkItem[
    WorkItemType[text()='Product Backlog Item'] 
        and 
    ./Childern/WorkItem/WorkItemType[text() = 'Task'] 
        and 
    not(./Childern/WorkItem/WorkItemType[text() = 'Product Backlog Item']) 
        and 
    ./Childern/WorkItem/WorkItemType[text() = 'Task']
]

UPDATE:

In response to the updated question, I would do something like this :

//WorkItem[WorkItemType[text()='Product Backlog Item']]
          [not(.//WorkItem/WorkItemType/text() != 'Task')]