Iterate over recursive struct with recursion function

Question

I have the following struct

    type Sitemap struct {
        XMLName        xml.Name `xml:"urlset"`
        Namespace      string   `xml:"xmlns,attr"`
        Schema         string   `xml:"xmlns:xsi,attr"`
        SchemaLocation string   `xml:"xsi:schemaLocation,attr"`
        Root           *URLItem
    }

    type URLItem struct {
        XMLName xml.Name `xml:"url"`
        Loc     string   `xml:"loc"`
        LastMod string   `xml:"lastmod,omitempty"`
        Urls    []*URLItem
    }

    func (s *Sitemap) AddURL(key string, url string) {
        node, found := findURLItemRecursive(s.Root, key)
        if found {
            node.Urls = append(node.Urls, &URLItem{Loc: url})
        }
    }


    func findURLItemRecursive(urlItem *URLItem, key string) (*URLItem, bool) {
        if urlItem.Loc == key {
            return urlItem, true
        }

        for _, urlItem := range urlItem.Urls {
            return findURLItemRecursive(urlItem, key)
        }

        return nil, false
    }

where the key is the parent URL and url is the child URL that is linked to the parent for the fact that the children it is found on the page of the parent.

For some unknown reasons findURLItemRecursive is buggy.

The issue is that I can't attach more UrlItem(s) at the second level.

I mean I can create the Root item create the Urls slices for the Root item but then I can't create nested slices. So I can't go more than the first level.

I'm wondering if the function findURLItemRecursive has any obvious bugs in Go that I can't spot.

The issue is that you are return from the loop, it causes your function to return immediately and doesn't traverse the array. — Parham Alvani
– Parham Alvani, Commented Jun 30, 2019 at 18:08

Parham Alvani · Accepted Answer · 2019-06-30 18:10:51Z

I think this should work for you.

    type Sitemap struct {
        XMLName        xml.Name `xml:"urlset"`
        Namespace      string   `xml:"xmlns,attr"`
        Schema         string   `xml:"xmlns:xsi,attr"`
        SchemaLocation string   `xml:"xsi:schemaLocation,attr"`
        Root           *URLItem
    }

    type URLItem struct {
        XMLName xml.Name `xml:"url"`
        Loc     string   `xml:"loc"`
        LastMod string   `xml:"lastmod,omitempty"`
        Urls    []*URLItem
    }

    func (s *Sitemap) AddURL(key string, url string) {
        node, found := findURLItemRecursive(s.Root, key)
        if found {
            node.Urls = append(node.Urls, &URLItem{Loc: url})
        }
    }


    func findURLItemRecursive(urlItem *URLItem, key string) (*URLItem, bool) {
        if urlItem.Loc == key {
            return urlItem, true
        }

        for _, urlItem := range urlItem.Urls {
            item, found := findURLItemRecursive(urlItem, key)
            if found {
                return item, found
            }
        }

        return nil, false
    }

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