[bug]: Nested arrays are not unwound from 3+ levels deep

[jose-cabral]

Background Information

• Module Version: 5.5.8
• Node/Browser Version: 20.0.9

The issue I'm reporting is with:

• json2csv
• csv2json

I have...

• searched to see if an issue has already been reported.
• verified that my JSON/CSV data is valid (using something like http://jsonlint.com or https://csvlint.io/).
• tried upgrading to the latest version of json-2-csv (since the issue may already be fixed).

Expected Behavior

When using expandArrayObjects: true and unwindArrays: true, all existent arrays should be expanded and unwonded.

Actual Behavior

From 3+ levels deep it does not always unwind or even expand all the arrays.

---

Example 1 ✅

Data Sample

JSON:

[
    {
      "Countries": [
        {
          "Cities": [
            {
              "Streets": [
                {
                  "Name": "Road 1",
                  "Number": 1
                },
                {
                  "Name": "Road 2",
                  "Number": 2
                }
              ]
            },
            {
              "field": "value"
            }
          ]
        }
      ]
    }
  ]

Expected CSV

Countries.Cities.Streets.Name	Countries.Cities.Streets.Number	Countries.Cities.field
Road 1	1	---
Road 2	2	---
---	---	value

Actual CSV✅

Countries.Cities.Streets.Name	Countries.Cities.Streets.Number	Countries.Cities.field
Road 1	1	---
Road 2	2	---
---	---	value

Code Example

// index.mjs
import { json2csv } from 'json-2-csv';

const options = {
    expandArrayObjects: true,
    unwindArrays: true,
    emptyFieldValue: '---' // just for the sake of readability
};
const json = [{"Countries":[{"Cities":[{"Streets":[{"Name":"Road 1","Number":1},{"Name":"Road 2","Number":2}]},{"field":"value"}]}]}];
const csv = json2csv(json, options);

console.log(csv);

---

Example 2 ❌

Data Sample

JSON:

[
    {
      "Countries": [
        {
          "Cities": [
            {
              "Streets": [
                {
                  "Name": "Road 1",
                  "Number": 1
                },
                {
                  "Name": "Road 2",
                  "Number": 2
                }
              ]
            }
          ]
        }
      ]
    }
  ]

Expected CSV

Countries.Cities.Streets.Name	Countries.Cities.Streets.Number
Road 1	1
Road 2	2

Actual CSV❌

Countries.Cities.Streets
[{"Name":"Road 1","Number":1},{"Name":"Road 2","Number":2}]

Code Example

// index.mjs
import { json2csv } from 'json-2-csv';

const options = {
    expandArrayObjects: true,
    unwindArrays: true,
    emptyFieldValue: '---' // just for the sake of readability
};
const json = [{"Countries":[{"Cities":[{"Streets":[{"Name":"Road 1","Number":1},{"Name":"Road 2","Number":2}]}]}]}];
const csv = json2csv(json, options);

console.log(csv);

---

Example 3 ❌

Data Sample

JSON:

[
    {
      "Continents": [
        {
          "Countries": [
            {
              "Cities": [
                {
                  "Streets": [
                    {
                      "Name": "Road 1",
                      "Number": 1
                    },
                    {
                      "Name": "Road 2",
                      "Number": 2
                    }
                  ]
                },
                {
                  "field": "value"
                }
              ]
            }
          ]
        }
      ]
    }
  ]

Expected CSV

Continents.Countries.Cities.Streets.Name	Continents.Countries.Cities.Streets.Number	Continents.Countries.Cities.field
Road 1	1	---
Road 2	2	---
---	---	value

Actual CSV❌

Continents.Countries.Cities
[{"Streets":[{"Name":"Road 1","Number":1},{"Name":"Road 2","Number":2}]},{"field":"value"}]

Code Example

// index.mjs
import { json2csv } from 'json-2-csv';

const options = {
    expandArrayObjects: true,
    unwindArrays: true,
    emptyFieldValue: '---' // just for the sake of readability
};
const json = [{"Continents":[{"Countries":[{"Cities":[{"Streets":[{"Name":"Road 1","Number":1},{"Name":"Road 2","Number":2}]},{"field":"value"}]}]}]}];
const csv = json2csv(json, options);

console.log(csv);

---

Note

I have the fix for this, I will open a PR soon

[jose-cabral]

PR is open