Function inferColumnType

apps/sim/lib/table/import.ts:135–159

(values: unknown[])

 * JSON is never inferred automatically.
 */
export function inferColumnType(values: unknown[]): Exclude<CsvColumnType, 'json'> {
  const nonEmpty = values.filter((v) => v !== null && v !== undefined && v !== '')
  if (nonEmpty.length === 0) return 'string'

  const allNumber = nonEmpty.every((v) => {
    const n = Number(v)
    return !Number.isNaN(n) && String(v).trim() !== ''
  })
  if (allNumber) return 'number'

  const allBoolean = nonEmpty.every((v) => {
    const s = String(v).toLowerCase()
    return s === 'true' || s === 'false'
  })
  if (allBoolean) return 'boolean'

  const isoDatePattern = /^\d{4}-\d{2}-\d{2}(T\d{2}:\d{2}(:\d{2})?)?/
  const allDate = nonEmpty.every((v) => {
    const s = String(v)
    return isoDatePattern.test(s) && !Number.isNaN(Date.parse(s))
  })
  if (allDate) return 'date'

  return 'string'
}

/**
 * Sanitizes a raw header into a valid column/table name. Strips disallowed