how to extract a value from a key:value pair inside of an object that's inside of an array

[novel wing]

basically, i'm running a database querry that returns an array of results as an array and an object inside of the array for every matching result
it doesn't really matter that it's a databse though, that's not my concern, my concern is how to extract the values from a specific key for every single object that gets returned?
for example;

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[tall jasper]

Sounds like you're looking for map() https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map

[novel wing]

What?

I haven't found how to extract a value from an object there though

[tall jasper]

You pass a function to the map method to return a new array of what you need

const results = []; // the array of objects in question

const newArr = results.map((strike) => strike.guard_username); // newArr is now string[]

console.log(newArr); // ['AstroHWeston','AstroHWeston',...]

[novel wing]

Okay, I got that down, but a user can have multiple strikes so I need to extract it from multiple objects, how can i do that then

[marble pasture]

Documentation suggestion for @novel wing:
Array.prototype.filter()
The filter() method of Array instances creates a shallow copy of a portion of a given array, filtered down to just the elements from the given array that pass the test implemented by the provided function.

[tall jasper]

check if it‘s the right user using filter

then map the resulting array

more importantly though, you‘re running a database query, so if you‘re only interested in specific results, then you should modify your query to do that for you

[novel wing]

im doing a querry on a username in a strikes datbase, a user can have multiple strikes which basically means it can return multiple results

[tall jasper]

and where’s the problem? I‘m having trouble understanding what you‘re stuck on

what‘s the end result you want to get from the array of objects

[novel wing]

basically, each object is a row in a database extract, meaning the key is a column and the value is the value of that column,
I need to extract a specific value from a specific column from all the objects, then put each single result on an embed, along with it's ID (which is another column in the database)

but i also need to reply with a specific message if the array is empty (aka, if the user has no strikes)

[tall jasper]

and why is a map not the solution for this? you have an array of object that you need to transform into an array of embeds based on each value

if you want to create one embedBuilder and append for each row of the array, there‘s also .reduce(), but I don‘t think that‘s even necessary in this case

[novel wing]

right but this doesn't return an array when i log it, it just logs a string

[tall jasper]

because that‘s how an array is stringified

[novel wing]

ah i see

[tall jasper]

Array.isArray(variable) can also show if it‘s an array

[novel wing]

yeah i know that but

[tall jasper]

it‘s general fuckery because console.log() is not the same as array.toString()

console.log() calls a formatting function

[novel wing]

okay wait let me go back one step though
let's say the querry returns an empty array, meaning there is nothing in the database, how would i handle that then? like i tried doing this but it didn't work

if (result === []) {
  //code here
} else {
  //code here
}

and it actually went into the else part and not the if part and i have no idea why

[tall jasper]

triple equality will always fail that.

That's because objects are compared using reference, not some deep equality.

const obj1 = {test: '1'}; // new reference
const obj2 = {test: '1'}; // new reference

console.log(obj1 === obj2) // False

Use result.length === 0 instead

[novel wing]

i console.logged the result before that and it logged []

[tall jasper]

essentially you're logging whether or not result and the newly created [] are stored at the same memory address, which is never possible

[novel wing]

ohhh okay that makes sense

one sec

[novel wing]

What did you mean here?

[tall jasper]

I wouldn‘t worry about it. Some less readable way to accomplish what you‘re going for

[novel wing]

okay let me get back on track now

[novel wing]

okay, im sorry if im annoying you lmao, but what if i wanted to get the number of how many results there are, in my case, how many objects technically (because each object is a strike)

cause i would be sending out how many strikes a specific person has

[tall jasper]

the length property of the array …

[novel wing]

oh does each object count as 1?

if so then that's simpler than i thought lmfao

[tall jasper]

out of curiosity, is javascript your first programming language?

[novel wing]

sort of yeah, why

[tall jasper]

discord.js is pretty complex for a starter project

[novel wing]

it's not really my first project though

plus im kind of forced to learn like 4 programming languages at once so lmfao 😭

[tall jasper]

well, the length of an array exists in almost every programming language

so that's why I suspected it

[novel wing]

ah i see what you mean

[novel wing]

wait can i just do arrName[objNumber].keyName

i always

tried to avoid fiddling around with complex array operations but

[tall jasper]

yeah, remember that [index] is 0-indexed though

[novel wing]

yes i know that

okay hold on let me try something

[novel wing]

okay, say someone had three strikes, and someone else only 1, would it be possible to show all of them as an embed description (not fields) using the same embed?

or actually i might just use fields

[tall jasper]

well, the description accepts one long string, so you can concatenate each object to a string variable

[novel wing]

i mean what if i wanted to use .setFields or .addFields in order to add the amount of fields that there are strikes for that user?

this is purely me brainstorming but couldnt i make a for loop to make it add fields to the embed until it's at the last array index?

[tall jasper]

yeah? addFields also accepts an array of embed fields

[novel wing]

wdym

[tall jasper]

result array -> .map() to APIEmbedField {name: string, value: string, inline?: boolean} -> pass it to EmbedBuilder.addFields()

[novel wing]

isn't it value, not description

[tall jasper]

my bad, value*

[novel wing]

or is this something else

right

[novel wing]

i'm having a bit of trouble understanding this

[tall jasper]

you should google keywords you don't understand. You must be able to immediately know what these terms mean if you want to build a discord bot

this is also mentioned in rule 3 of this discord

https://discord.js.org/docs/packages/discord.js/main don't forget the discordjs docs and
https://developer.mozilla.org/en-US/ mdn docs

[novel wing]

i just

don't know what APIEmbedField is supposed to mean

im looking at the guide rn

[tall jasper]

It's a type that describes an embed field that the discord API accepts. {name: string, value: string, inline?: boolean}

https://discord-api-types.dev/api/discord-api-types-v10/interface/APIEmbedField

[novel wing]

yeah but doesn't addFields require you to put in the amount of objects that you want the fields? some people might have more and some might have less it's not a static number

i can explain more if you misunderstood because i might've not explained it the best 😅

[tall jasper]

there's the upper limit of 25 due to how discord set that limit, but there's no limit for passing fields to the function

it uses rest parameters / spread operator

[novel wing]

yeah but if i set the title as an index from an array, which index doesn't exist, wouldn't that error and crash?

like if i added 5 fields and someone only had 2 strikes for example

[tall jasper]

no, because if you followed that pipeline I explained above that is impossible

map() applies the function to each element, which can't go out of bounds
passing the array to .addFields() uses the content within, but can't go out of bounds

if you loop over an array and are out of bounds, then you wrote your for loop wrong.

[novel wing]

oh yeah about that pipeline

oh wait im supposed to be using a for loop

i moved it far out of the way lmfao one sec

[tall jasper]

this doesn't use a for loop.

[novel wing]

oh

[novel wing]

okay wait so i got this far

const yesStrikes = new EmbedBuilder()
                                    .setTitle(`${result.length} strikes found for ${guardNickname}`)
                                    .setColor('#17d058')
                                    //result.map().to
                                const newID = result.map((id) => id.strike_id);
                                const newReason = result.map((strike) => strike.strike_reason);

[tall jasper]

I think you misunderstand what map does.

const newArray = [];
for (let i = 0; i < result.length; i++) {
  const id = result[i];
  newArray.push(id.strike_id);
}

is the same as

const newArray = result.map((id) => id.strike_id);

it can transform to ANY value. The function in map receives a strike object as parameter, and whatever you return ends up in the new array

that includes transforming the strike object into an APIEmbedField

If that confuses you, then I suggest looking up the following concepts

• General: Callback Function
• JavaScript: Arrow Function Syntax

[novel wing]

so basically .map just executes a function on every single element in an array

[tall jasper]

correct!

[novel wing]

meaning for me to add fields to an embed

it would add a new field

for every element in an array?

[tall jasper]

map is specifically meant for returning the function's value

it returns an array that has the same length as result, but each element within was changed according to the passed function

in this case, it's function(id) { return id.strike_id; }

[novel wing]

right so i need

ok so basically

what you're telling me i need to do is

since an object is a single element in an array

i need the function to extract the strike_id value from each object in an array, and then store it in a separate array

?

[tall jasper]

you need to take each strike object and change it into an APIEmbedField. Then you can return that newly created object

since you now have an array of APIEmbedField, you can pass it to EmbedBuilder.addFields()

[novel wing]

hmm wait i have an idea

[novel wing]

so if i did
const newID = result.map((id) => id.strike_id);
that would return.. an object?

[tall jasper]

it would return a string

since strike_id is a string

[novel wing]

yeah but i did console.log(typeof newID) and that

logged objewct

[tall jasper]

oh that

it‘s an array of strings

arrays are objects in javascript so typeof logged that

[novel wing]

ohhh

okay

OH okay i was

thinking of something else

[novel wing]

okay well then cant i just make a for loop for .addField and it would repeat as much times as there are elements in either one of the arrays

so

const newID = result.map((id) => id.strike_id);
                                const newReason = result.map((strike) => strike.strike_reason);
                                for (let i = 0; i <= newID.length; i++) {
                                        yesStrikes.addFields(
                                            {title: `${newReason[i]}`, value: `${newID[i]}`}
                                        )
                                    }

[tall jasper]

you can. There‘s always multiple ways

[novel wing]

ah

[tall jasper]

that code will fail though since i = newID.length is out of bounds

remember, 0 indexed. So i goes from 0 to newID.length - 1

[novel wing]

oh so

[novel wing]

is it because i put <= instead of <

[tall jasper]

yes

[novel wing]

uhh that still crashes

OHH WAIT

i set it to title: not name:

i think

oh okay that fixed it, thank you so much for the time <3

I'll keep this open just in case I need something

I'll close it later today

[novel wing]

@tall jasper hey sorry for the ping but i have another question, i added a new column to the database which is date_issued which just stores a UNIX timestamp of when the command was ran.
Now when I try to print out those times on an embed using the same maping method as we described before, but it prints out the two values that are in the database for both cases, why is that?

const newID = result.map((id) => id.strike_id);
const newReason = result.map((strike) => strike.strike_reason);
const newTime = result.map((time) => time.date_issued)
for (let i = 0; i < newID.length; i++) {
  yesStrikes.addFields(
    { name: `${newReason[i]}`, value: `Strike ID: ${newID[i]} | <t:${newTime}>` }
  )
}

Sorry for the ping btw

never the fuck mind im blind as fuck

i swear to god i ask for help and as soon as i do it clicks

[tall jasper]

get a rubber duck so you can ask it first

if it clicks immediately, it‘ll work