replace-enum-postgresql/src/index.js

This package provides the methods needed to replace a PostgreSQL ENUM (ie., in migrations).

/**
 * Since PostgreSQL still does not support remove values from an ENUM,
 * the workaround is to create a new ENUM with the new values and use it
 * to replace the other.
 *
 * @param {Object} args
 * @param {String} args.tableName
 * @param {String} args.columnName
 * @param {String} args.defaultValue
 * @param {Array}  args.newValues
 * @param {Object} args.queryInterface
 * @param {String} args.enumName - Optional.
 *
 * @return {Promise}
 */
export default (args) => {
  const {
    tableName,
    columnName,
    defaultValue,
    newValues,
    queryInterface,
    enumName = `enum_${tableName}_${columnName}`
  } = args;

  const newEnumName = `${enumName}_new`;

  return queryInterface.sequelize.transaction((t) => {
    const sequelizeOptions = { transaction: t };

    // Create a copy of the type
    return createEnum(
      { queryInterface, name: newEnumName, values: newValues, sequelizeOptions }
    )
      // Drop default value (ALTER COLUMN cannot cast default values)
      .then(() => unsetDefaultValueFromEnum(
        { queryInterface, tableName, columnName, sequelizeOptions }
      ))
      // Change column type to the new ENUM TYPE
      .then(() => setColumnTypeToEnum({
        tableName,
        columnName,
        enumName: newEnumName,
        queryInterface,
        sequelizeOptions
      }))
      // Drop old ENUM
      .then(() => dropEnum({ enumName, sequelizeOptions, queryInterface }))
      // Rename new ENUM name
      .then(() => renameEnum({
        oldEnumName: newEnumName,
        newEnumName: enumName,
        queryInterface,
        sequelizeOptions
      }))
      .then(() => setColumnDefault({
        tableName,
        columnName,
        defaultValue,
        defaultValueType: enumName,
        queryInterface,
        sequelizeOptions
      }));
  });
}

/**
 * Create a new ENUM.
 *
 * @param {Object}   args
 * @param {String}   args.name
 * @param {String[]} args.values
 * @param {Object}   args.sequelizeOptions
 * @param {Object}   args.queryInterface
 *
 * @return {Promise}
 */
export function createEnum(args) {
  return args.queryInterface.sequelize.query(
    getQueryToCreateEnum(args.name, args.values),
    args.sequelizeOptions
  );
}

/**
 * Returns the query to create an Enum.
 *
 * @param {String}   name
 * @param {String[]} values
 *
 * @return {String}
 */
export function getQueryToCreateEnum(name, values) {
  return `CREATE TYPE "${name}" AS ENUM ('${values.join('\', \'')}')`;
}

/**
 * Unset default value from ENUM.
 *
 * @param {Object} args
 * @param {String} args.tableName
 * @param {String} args.columnName
 * @param {Object} args.sequelizeOptions
 * @param {Object} args.queryInterface
 *
 * @return {Promise}
 */
export function unsetDefaultValueFromEnum(args) {
  return args.queryInterface.sequelize.query(
    getQueryToRemoveDefaultFromColumn(args.tableName, args.columnName),
    args.sequelizeOptions
  );
}

/**
 * Get the query to drop default value for a column.
 *
 * @param {String} tableName
 * @param {String} columnName
 *
 * @return {String}
 */
export function getQueryToRemoveDefaultFromColumn(tableName, columnName) {
  return `ALTER TABLE "${tableName}" ALTER COLUMN "${columnName}" DROP DEFAULT`;
}

/**
 * Set the column type to an Enum.
 *
 * @param {Object} args
 * @param {String} args.tableName
 * @param {String} args.columnName
 * @param {String} args.enumName
 * @param {Object} args.sequelizeOptions
 *
 * @return {Promise}
 */
export function setColumnTypeToEnum(args) {
  return args.queryInterface.sequelize.query(
    getQueryToSetEnumType(args.tableName, args.columnName, args.enumName),
    args.sequelizeOptions
  );
}

/**
 * Get the query to set a column type to an Enum.
 *
 * @param {String} tableName
 * @param {String} columnName
 * @param {String} enumName
 *
 * @return {String}
 */
export function getQueryToSetEnumType(tableName, columnName, enumName) {
  return `
    ALTER TABLE "${tableName}"
      ALTER COLUMN "${columnName}"
        TYPE "${enumName}"
        USING ("${columnName}"::text::"${enumName}")
  `;
}

/**
 * Drop an Enum.
 *
 * @param {Object} args
 * @param {Object} args.queryInterface
 * @param {String} args.enumName
 * @param {Object} args.sequelizeOptions
 *
 * @return {Promise}
 */
export function dropEnum(args) {
  return args.queryInterface.sequelize.query(
    getQueryToDropEnum(args.enumName),
    args.sequelizeOptions
  );
}

/**
 * Get the query to drop an Enum.
 *
 * @param {String} enumName
 *
 * @return {String}
 */
export function getQueryToDropEnum(enumName) {
  return `DROP TYPE "${enumName}"`;
}

/**
 * Rename an Enum.
 *
 * @param {Object} args
 * @param {Object} args.queryInterface
 * @param {String} args.oldEnumName
 * @param {String} args.newEnumName
 * @param {Object} args.sequelizeOptions
 *
 * @return {Promise}
 */
export function renameEnum(args) {
  return args.queryInterface.sequelize.query(
    getQueryToRenameEnum(args.oldEnumName, args.newEnumName),
    args.sequelizeOptions
  );
}

/**
 * Get the query to rename an enum.
 *
 * @param {String} oldEnumName
 * @param {String} newEnumName
 *
 * @return {String}
 */
export function getQueryToRenameEnum(oldEnumName, newEnumName) {
  return `ALTER TYPE "${oldEnumName}" RENAME TO "${newEnumName}"`;
}

/**
 * Set the default value for a column.
 *
 * @param {Object} args
 * @param {Object} args.queryInterface
 * @param {String} args.tableName
 * @param {String} args.columnName
 * @param {String} args.defaultValue
 * @param {String} args.defaultValueType
 * @param {Object} args.sequelizeOptions
 *
 * @return {Promise}
 */
export function setColumnDefault(args) {
  return args.queryInterface.sequelize.query(
    getQueryToSetColumnDefault(
      args.tableName,
      args.columnName,
      args.defaultValue,
      args.defaultValueType
    ),
    args.sequelizeOptions
  );
}

/**
 * Get the query to set the default value for a column.
 *
 * @param {String} tableName
 * @param {String} columnName
 * @param {String} defaultValue
 * @param {String} defaultValueType
 *
 * @return {String}
 */
export function getQueryToSetColumnDefault(tableName, columnName, defaultValue, defaultValueType) {
  return `
    ALTER TABLE "${tableName}"
      ALTER COLUMN "${columnName}"
        SET DEFAULT '${defaultValue}'::${defaultValueType}
  `;
}