Array Detection

Lua doesn't have a separate array type. Both arrays and dictionaries are tables. This means luadata needs a strategy for deciding when a table should become a JSON array vs a JSON object.

There are two ways to write array-like tables in Lua. The first uses implicit indices:

fruits = {"apple", "banana", "cherry"}

The second uses explicit integer keys:

fruits = {
    [1] = "apple",
    [2] = "banana",
    [3] = "cherry",
}

Both represent the same data in Lua, but the intent may differ. By default, luadata uses ArrayModeSparse with a MaxGap of 20, which renders both forms as JSON arrays:

{
  "fruits": [
    "apple",
    "banana",
    "cherry"
  ]
}

The array mode option gives you control over this behavior. The chosen mode applies to all tables in the output. If you need per-field control, a JSON Schema can declare each field's type explicitly — see Schema vs Heuristics.

The next three examples cover each array mode in detail.