error.ts

import { Message } from "./connection.ts";

export interface ErrorFields {
  severity: string;
  code: string;
  message: string;
  detail?: string;
  hint?: string;
  position?: string;
  internalPosition?: string;
  internalQuery?: string;
  where?: string;
  schemaName?: string;
  table?: string;
  column?: string;
  dataType?: string;
  contraint?: string;
  file?: string;
  line?: string;
  routine?: string;
}

export class PostgresError extends Error {
  public fields: ErrorFields;

  constructor(fields: ErrorFields) {
    super(fields.message);
    this.fields = fields;
    this.name = "PostgresError";
  }
}

export function parseError(msg: Message): PostgresError {
  // https://www.postgresql.org/docs/current/protocol-error-fields.html
  const errorFields: any = {};

  let byte: number;
  let char: string;
  let errorMsg: string;

  while ((byte = msg.reader.readByte())) {
    char = String.fromCharCode(byte);
    errorMsg = msg.reader.readCString();

    switch (char) {
      case "S":
        errorFields.severity = errorMsg;
        break;
      case "C":
        errorFields.code = errorMsg;
        break;
      case "M":
        errorFields.message = errorMsg;
        break;
      case "D":
        errorFields.detail = errorMsg;
        break;
      case "H":
        errorFields.hint = errorMsg;
        break;
      case "P":
        errorFields.position = errorMsg;
        break;
      case "p":
        errorFields.internalPosition = errorMsg;
        break;
      case "q":
        errorFields.internalQuery = errorMsg;
        break;
      case "W":
        errorFields.where = errorMsg;
        break;
      case "s":
        errorFields.schema = errorMsg;
        break;
      case "t":
        errorFields.table = errorMsg;
        break;
      case "c":
        errorFields.column = errorMsg;
        break;
      case "d":
        errorFields.dataTypeName = errorMsg;
        break;
      case "n":
        errorFields.constraint = errorMsg;
        break;
      case "F":
        errorFields.file = errorMsg;
        break;
      case "L":
        errorFields.line = errorMsg;
        break;
      case "R":
        errorFields.routine = errorMsg;
        break;
      default:
        // from Postgres docs
        // > Since more field types might be added in future,
        // > frontends should silently ignore fields of unrecognized type.
        break;
    }
  }

  return new PostgresError(errorFields);
}