How Can I Efficiently Traverse XML Data in Go Without Using XPath?

XML Data Traversal in Go

Problem:

XML data often presents challenges when it comes to accessing specific elements without prior knowledge of their XPath. The xml.Unmarshal method has limitations in this regard, requiring users to specify exact paths to obtain data.

Solution:

To traverse through XML data flexibly, we can utilize a recursive data structure alongside a simple walk function.

Recursive Data Structure:

type Node struct {
    XMLName xml.Name
    Content []byte `xml:",innerxml"`
    Nodes   []Node `xml:",any"`
}

In this structure, each Node represents an element in the XML document, containing its name, inner XML content (for non-nested elements), and a slice of children nodes.

Walk Function:

func walk(nodes []Node, f func(Node) bool) {
    for _, n := range nodes {
        if f(n) {
            walk(n.Nodes, f)
        }
    }
}

The walk function recursively traverses through the Node tree, calling the provided function f for each encountered node.

Usage:

To traverse through an XML document and process its elements accordingly:

1. Unmarshal the XML data into a Node struct.
2. Define a filter function f that specifies the criteria for processing nodes (e.g., based on element name or content).
3. Call the walk function with the root node and the filter function as parameters.

Example:

The following code traverses the XML document in the question, printing the element names in order:

content := Node{}
if err := xml.Unmarshal([]byte(rawXML), &content); err != nil {
    // Handle error
}

walk(content.Nodes, func(n Node) bool {
    fmt.Println(n.XMLName.Local)
    return true
})

Output:

content
p
animal
p
dog
p
birds
p
p
animal
p

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