Using complex JSON functions

/**
 * Takes an object and returns a Postgres json_build_object()
 * @param obj A map of any shape
 * @param alias Column alias
 * @returns json_build_object() SQL code
 */
export function jsonBuildObjectSql(
  obj: Record<string, unknown>,
  alias?: string,
  checkFieldForNull?: string
): string {
  return (
    (checkFieldForNull
      ? `case when ${checkFieldForNull} is not null then `
      : '') +
    'json_build_object(' +
    Object.entries(obj)
      .map(pair => [`'${pair[0]}'`, pair[1]])
      .join(', ') +
    ')' +
    (checkFieldForNull ? ' else null end' : '') +
    (alias ? ` as ${alias}` : '')
  );
}