Maintain ordering

[vjpr]

Is your feature request related to a problem? Please describe.

In order to do xml -> json -> xml without any re-ordering, children must always be in an array, not grouped by their tag type.

<foo>
  <bar></bar>
  <baz></baz>
  <bar></bar>
</foo>

Describe the solution you'd like

Like xml-js does with {compact: false}. An option where all children are always an array.

Describe alternatives you've considered

Manipulating the DOM instead which maintains ordering.

[oozcitak]

Did you try the verbose option?

https://oozcitak.github.io/xmlbuilder2/serialization.html#js-object-and-map-serializers

[vjpr]

Yeh, but if you have a node that has children of different element types interspersed, it groups by the element type. Which loses ordering.

[oozcitak]

Can you create a test case to reproduce?

[vjpr]

The structure of the object seems to change depending on whether there are intersperesed children of different types or not. In order to use the serialized object, I need a consistent structure.

    <?xml version="1.0"?>
    <root>
      <person age="35"/>
      <person age="30"/>
      <ele>simple element</ele>
    </root>

      {
        "root": [
          {
            "person": [
              {
                "@age": "35"
              },
              {
                "@age": "30"
              }
            ],
            "ele": [
              "simple element"
            ]
          }
        ]
      }

    <?xml version="1.0"?>
    <root>
      <person age="35"/>
      <ele>simple element</ele>
      <person age="30"/>
    </root>

      {
        "root": [
          {
            "#": [
              {
                "person": [
                  {
                    "@age": "35"
                  }
                ]
              },
              {
                "ele": [
                  "simple element"
                ]
              },
              {
                "person": [
                  {
                    "@age": "30"
                  }
                ]
              }
            ]
          }
        ]
      }

---

Test case:

// @ts-nocheck

import $$ from '../TestHelpers'

describe('Replicate issue', () => {

  test('#104 - Maintain ordering for interspersed children of different element type', () => {
    const xmlA = $$.t`
    <?xml version="1.0"?>
    <root>
      <person age="35"/>
      <ele>simple element</ele>
      <person age="30"/>
    </root>
    `

    const xmlB = $$.t`
    <?xml version="1.0"?>
    <root>
      <person age="35"/>
      <person age="30"/>
      <ele>simple element</ele>
    </root>
    `

    const expectedObjA = {
      'root': {
        '#': [
          {
            'person': {
              '@age': '35'
            }
          },
          {
            'ele': 'simple element'
          },
          {
            'person': {
              '@age': '30'
            }
          }
        ]
      }
    }

    const expectedObjB = {
      'root': {
        '#': [
          {
            'person': {
              '@age': '35'
            }
          },
          {
            'person': {
              '@age': '30'
            }
          },
          {
            'ele': 'simple element'
          },
        ]
      }
    }

    const verbose = true
    const group = false
    const format = 'map'

    const docA = $$.create(xmlA)
    const docB = $$.create(xmlB)
    const objA = docA.end({format, verbose, group})
    const objB = docB.end({format, verbose, group})

    console.log(JSON.stringify(toObject(objA), null, 2))
    console.log(JSON.stringify(toObject(objB), null, 2))

    expect(toObject(objA)).toEqual(expectedObjA)
    expect(toObject(objB)).toEqual(expectedObjB)

    const xmlFromObjA = $$.create(objA).end({prettyPrint: true})
    const xmlFromObjB = $$.create(objB).end({prettyPrint: true})

    expect(xmlFromObjA).toEqual(xmlA)
    expect(xmlFromObjB).toEqual(xmlB)
  })

})

const toObject = (map = new Map) => {
  if (!(map instanceof Map)) return map
  return Object.fromEntries(Array.from(map.entries(), ([k, v]) => {
    if (v instanceof Array) {
      return [k, v.map(toObject)]
    } else if (v instanceof Map) {
      return [k, toObject(v)]
    } else {
      return [k, v]
    }
  }))
}

[vjpr]

So actually, it doesn't lose ordering...but the serialized object is inconsistent, making it difficult to traverse.

~I think format=map actually works as expected.~

I need to work with a JSON object because I want to modify things, and then diff, which is more difficult with the DOM.

I think verbose should force all children under a # - so that regardless of interspersal of children, you get the same object structure. Or could make it a separate option.

[iMrDJAi]

@oozcitak Hello! Any update on this? We can't trust that object keys are going to remain in the same order, children need to be contained inside arrays.