I have a React application which handles rooms and their statistics.
Previously, I had the code set up to pass as props to the next component:
the raw statistics (not a concern for the question)
an array of all the rooms set up as follows
I figured it would be simpler for me, though, to have the list of all rooms as an associative array where the keys of each element is the same as the ID it contains. To do that, I utilized a code similar to this in a for loop:
roomsList[rooms[v].ID] = rooms[v];
So that the result would be:
[a001: {...}, a002: {...}, ...]
I then proceeded to pass this style of array, and not the standard one with a numeric index, as a prop to the next component as such:
<StatsBreakdown stats={computedStats.current} roomsList={roomsList} />
BUT
Now, the next component sees that prop as an empty array.
Even more weirdly, if I initialize that roomsList array with a random value [0] and then do the same process, I end up with:
I cannot cycle through the array with .map, and, according to JS, the length is actually 0, it's not only Google Chrome.
Is there something I'm missing about the way JSX, JS or React work?
Your original roomsList was an array of objects, whose indices were 0,1,2 etc. roomsList[rooms[v].ID] = rooms[v]; implies you are inserting elements not using a number but an alphanumeric string. Hence your resulting array is no longer an array but an object.
So we can cycle over the object using Object.keys().
const renderRoomDets = Object.keys(roomsList).map(room => {
roomOwner = roomsList[room].owner_id;
return (
<div>
<p>{`Room Owner ${roomOwner}`}</p>
</div>
);
});
But I believe your original form is ideal, because you are reaping no special benefits from this notation.
A better alternative maybe using .find() or .findIndex() if you want iterate over an array based on a specific property.
const matchedRoom = roomsList.find(room => room.ID === 'Srf4323')
Iterate the new array using its keys not indexes.
Or even better store your data in an actual object instead of an array since you're using strings for ids.
First define your object like so:
let data = {};
Then start adding records to it. I'd suggest deleting the ID attribute of the object since you're storing it in the key of your record, it's redundant, and it won't go anywhere unless u delete the entry.
data[ID] = row;
To delete the ID attribute (optional):
row.ID = null;
delete row.ID;
Then iterate through it using
for(let key in data){}
Related
I have the mapping of abbreviation and full name as follow:
object = {"TSLA":"TESLA INC.","GOOG":"GOOGLE INC.","APPL":"APPLE INC.","AMZN":"AMAZON CORPORATION", "MSFT":"MICROSOFT CORPORATION"}
as an output of function i get the following array:
array = ["AMZN","APPL"]
I want to display the values of the associated keys as follows:
output_array = ["AMAZON CORPORATION", "APPLE INC."]
Note that, the actual object has more key: value pairs
Using IndexOf() I can replace one value. However, I believe there must be a way of mapping the array elements to replace the values at once.
Since I am new to JS, I would appreciate any suggestion.
array.map(abbr => object[abbr]) does the job; it iterates over the array rather than the object, which is more efficient as the object already is a lookup table with the right keys - you are right, there is no need to use indexOf which uses a linear search.
I have this array
switched = {"Restaurant":1,"Hotel":2,"Beauty shop":3,"Physiotherapist":4,"Dentist":5,"Bar":6,"Coffee shop":7}
and this object
result = [{"Google Place URL":"http://www.restaurant.com","Business Type":"Restaurant"},{"Google Place URL":"http://www.hotel.com","Business Type":"Hotel"}]
I want to validate if every item of the result contains words of switched
also, I'm already working with a for that returns each item separately
item[csvBusinessType] = Restaurant
how can I validate if item[csvBusinessType] is included in switched?
I have tried with
let n = switched.includes(item[csvBusinessType]);
but I get Uncaught TypeError: switched.includes is not a function
There is not good native method for this. Better to use lodash library https://www.npmjs.com/package/lodash
Here is an example
const _ = require('lodash');
console.log( _.includes(switched, item[csvBusinessType]));
I converted the object to string and used includes, I don't know if it will be the best way, but I think it is the most supported by browsers
let businessListArray = JSON.stringify(switched);
let checkBusiness = businessListArray.includes(item[csvBusinessType]);
I want to validate if every item of the result contains words of switched
If you want to validate that every item of the result object array contains words of the switched array, you should look into JS Array methods and working with Objects, just as #Andreas suggested.
In this specific case, your switched object has keys that appear to match the csvBusinessType of your item objects. This is helpful as we can use Object.keys() to grab all the keys of your switched object as an array of strings.
const businessTypes = Object.keys(switched) // = ["Restaurant","Hotel","Beauty shop","Physiotherapist","Dentist","Bar","Coffee shop"]
Now that we have grabbed the keys that you want to check against, we can use the JS Array method every() to perform a test against every object in your result object array. In this case, we will be testing that the obect's Business Type is included in our newly created businessTypes array.
const resultsValid = result.every((resultObject) => businessTypes.includes(resultObject["Business Type"]));
resultsValid is a boolean that is true if all objects in result had a Business type that matched one of the keys of your switched object.
NOTE: You may want to check Letter Casing before some of these comparisons unless you want to explicitly match only exact matches ("Beauty shop" will NOT match "Beauty Shop" for example).
I'm working with a web framework and I'm using variables from Python into Javascript code.
I get next array in Python, which can contain more than one cell with dictionaries inside it:
[[{'lacp_use-same-system-mac': u'no'}, {'lacp_mode': u'passive'}, {'lacp_transmission-rate': u'slow'}, {'lacp_enable': u'no'}]]
I want to be able to access every cell array and, after that, get every keys from the dictionary inside this cell array. Up to now, I only have arrays or dictionaries, so for both cases I did next:
var X = JSON.parse(("{{X|decodeUnicodeObject|safe}}").replace(/L,/g, ",").replace(/L}/g, "}").replace(/'/g, "\""));
Where X is the Python variable. Unfortunately, this does not run with the array I wrote above.
How can I do that?
Thanks beforehand,
Regards.
I want to be able to access every cell array and, after that, get
every keys from the dictionary inside this cell array
If I understood correctly you want to get the keys of a nested array.
Note: your array isn't valid js.
const arrarr = [[{key1: 'val1'}, {key2: 'val2'}], [{key3: 'val3'}, {key4: 'val4'}]];
arrarr.forEach(arr => {
arr.forEach(e => {
Object.keys(e).forEach(k => console.log(k))
})
})
If the depth of nests is of arbitrary depth you can use recursion and check if the child is an array, if it is keep going, else get the keys.
Using my micro:bit I am trying to add the value of a variable called sendText to an array without overwriting its previous stored value for that variable.
input.onGesture(Gesture.Shake, () => {
list.push(sendText)
binSend = 0
basic.showString(sendText)
})
My array is called list
let list: string[] = []
I am trying to store single characters in an array then outputting them. If there is a better alternative to using an array I would gladly accept it.
To add a value to an array you use push function, after, if you need to group the characters pushed to array for output you could to use for your specific example list.join('')
I have a parse data model like...
Parent
------
children - Array of pointers to Child objects
I'm trying to create a query that says...
Find all Parents where the children array contains the specific Child object.
It's sort of the opposite of this function from the docs.
query.containedIn("playerName", ["Jonathan Walsh", "Dario Wunsch", "Shawn Simon"]);
// note you can also do this with object pointers which is EXACTLY opposite to what I want.
This will find all the players where the playerName is contained in the given array.
I want this but I want to give a value and that value to be in the array for the key.
I imagine it's something like...
query.contains("children", someChildObject);
but the docs for contains shows it only works for substrings of strings.
How would I do what I'm looking for?
You should use query.equalTo for key with an array type.
Try query like following:
var ChildClass = Parse.Object.extend('ChildClass');
var childObj = new ChildClass();
childObj.id = 'objId';
// you don't need to do above if you already have the object.
query.equalTo("children", childObj);
...
ref. Queries on Array Values