guillaumewuip

DROP PROCEDURE IF EXISTS getLogsForModule;

DELIMITER $$
CREATE PROCEDURE getLogsForModule(module VARCHAR(255))
BEGIN
	-- on doit passer par un concat car le nom d'une table doit être statique
    SET @request = CONCAT("SELECT l.*, i.*, c.*, category_path(c.category) as category_path, u.*
        FROM mdl_logstore_standard_log l
        LEFT OUTER JOIN mdl_", module, " i ON i.id = l.objectid
        LEFT OUTER JOIN mdl_course c ON c.id = l.courseid

guillaumewuip

// Message.ts
export type TextMessage = {
  text: string;
}

export type ImageMessage = {
  mimeType: string;
  url: string;
  description: string;
}

guillaumewuip

// Message.ts
export type Message = TextMessage | ImageMessage | AudioMessage;

guillaumewuip

import { Message } from ‘./Message’

function renderMessage(message: Message) {
  if (message.text) {
    // ok we know it’s a TextMessage
    return <TextComponent text={message.text} />
  }

  if (message.url) {
    // Problem!

guillaumewuip

export type TextMessage = {
  messageType: 'TEXT';
  ...
}

export type ImageMessage = {
  messageType: 'IMAGE';
  ...
}

guillaumewuip

function renderMessage(message: Message) {
  if (message.messageType === 'TEXT') {
    // message is typed as TextMessage here
    return <TextComponent text={message.text} />
  }

  if (message.messageType === 'IMAGE') {
    // message is typed as ImageMessage here
    return <ImageComponent url={message.url} description={message.description} />
  }

guillaumewuip

// If this function returns true, TS will know the message variable is a TextMessage
function isText(message: Message): message is TextMessage {
  return message.messageType === ‘TEXT’;
}

// Repeat for isImage and isAudio

guillaumewuip

if (isText(message)) {
  return <TextComponent text={message.text} />
}

guillaumewuip

import { Option, fold } from ‘fp-ts/lib/Option`;

const user: Option<User> = … // ie. None | Some<User>

return fold(
    () => <p>oops, no user!</p>,
    (user: User)  => <UserView user={user} />,
)(user);

guillaumewuip

// Message.ts
function fold<R>(
  onText: (message: TextMessage) => R,
  onImage: (message: ImageMessage) => R,
  onAudio: (message: AudioMessage) => R,
) => {
  return (message: Message): R => {
    switch (message.messageType) {
      case ‘TEXT’:
        return onText(message);