Function that yields promise result

Question

Function that yields promise result

I need help figuring out how to make this recursive function return a promise value. I've attempted various approaches, but they all resulted in the search variable ending up as undefined.

public search(message: Message) {
    let searchResult: string;
    const filter = (msg: Message) => msg.author.id === message.author.id;
    message.channel.send('Please enter a search term').then(msg => {
      message.channel.awaitMessages(filter, { max: 1 })
        .then(collected => {
            if (collected.first()!.content === 'Test') this.search(message);
            msg.delete()
            collected.first()!.delete()
            searchResult = collected.first()!.content
          })
        })
    })
    return searchResult; // Error: Variable 'search' is used before being assigned.ts(2454)
  }

javascript typescript discord.js

Answer 1

Answer №1

Have you thought about incorporating an asynchronous function into your code? It could significantly improve the readability and debugging process.

public async search(message: Message): Promise<any> {
    const filter = (msg: Message) => msg.author.id === message.author.id;
    const msg = await message.channel.send('Please enter a search term');
    const collected = await message.channel.awaitMessages(filter, { max: 1 });
    if (collected.first()!.content === 'Test') return this.search(message);
    msg.delete();
    collected.first()!.delete();
    const search = collected.first()!.content;
    return search;
}

In this snippet, search is declared as a constant and immediately returned, which is acceptable to the compiler. I didn't use a variable to store the result of the nested this.search call, but you may need to do so if you plan to execute additional code after obtaining the actual result.

Answer 2

Have you thought about incorporating an asynchronous function into your code? It could significantly improve the readability and debugging process.

public async search(message: Message): Promise<any> {
    const filter = (msg: Message) => msg.author.id === message.author.id;
    const msg = await message.channel.send('Please enter a search term');
    const collected = await message.channel.awaitMessages(filter, { max: 1 });
    if (collected.first()!.content === 'Test') return this.search(message);
    msg.delete();
    collected.first()!.delete();
    const search = collected.first()!.content;
    return search;
}

In this snippet, search is declared as a constant and immediately returned, which is acceptable to the compiler. I didn't use a variable to store the result of the nested this.search call, but you may need to do so if you plan to execute additional code after obtaining the actual result.

Answer 3

Answer №2

In this code snippet, the 'search' function will always return undefined because it exits before any asynchronous action completes. To fix this, you should return the first Promise and handle subsequent asynchronous actions in the '.then' callbacks:

public search(message: Message) {
  const filter = (msg: Message) => msg.author.id === message.author.id;
    // Return the first promise immediately
  return message.channel.send('Enter search term').then(msg => {
    // Once the first promise resolves, continue with the second one
    return message.channel.awaitMessages(filter, { max: 1 }).then(collected => {
      // Finally, return the desired value
      if (collected.first()!.content === 'Test') this.search(message);
      msg.delete();
      collected.first()!.delete();
      return collected.first()!.content;
    });
  });
}

To avoid nested promises and reduce callback complexity, we can utilize Promise.all:

public search(message: Message) {
  const filter = (msg: Message) => msg.author.id === message.author.id;
  return message.channel.send('Enter search term')
    .then(msg => Promise.all([
      msg,
      message.channel.awaitMessages(filter, { max: 1 })
    ]))
    .then(([msg, collected]) => {
      if (collected.first()!.content === 'Test') this.search(message);
      msg.delete();
      collected.first()!.delete();
      return collected.first()!.content;
    });
}

Using Promise.all allows us to simplify the promise handling without nesting them deeply.

Answer 4

In this code snippet, the 'search' function will always return undefined because it exits before any asynchronous action completes. To fix this, you should return the first Promise and handle subsequent asynchronous actions in the '.then' callbacks:

public search(message: Message) {
  const filter = (msg: Message) => msg.author.id === message.author.id;
    // Return the first promise immediately
  return message.channel.send('Enter search term').then(msg => {
    // Once the first promise resolves, continue with the second one
    return message.channel.awaitMessages(filter, { max: 1 }).then(collected => {
      // Finally, return the desired value
      if (collected.first()!.content === 'Test') this.search(message);
      msg.delete();
      collected.first()!.delete();
      return collected.first()!.content;
    });
  });
}

To avoid nested promises and reduce callback complexity, we can utilize Promise.all:

public search(message: Message) {
  const filter = (msg: Message) => msg.author.id === message.author.id;
  return message.channel.send('Enter search term')
    .then(msg => Promise.all([
      msg,
      message.channel.awaitMessages(filter, { max: 1 })
    ]))
    .then(([msg, collected]) => {
      if (collected.first()!.content === 'Test') this.search(message);
      msg.delete();
      collected.first()!.delete();
      return collected.first()!.content;
    });
}

Using Promise.all allows us to simplify the promise handling without nesting them deeply.

Function that yields promise result

Answer №1

Answer №2

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