CODEWITHSUNDEEP
javascriptsqlitereact-nativeexpo
zoonosis
zoonosis

Reputation: 799

How to add a new key:value pair to an already existing array state variable react native

I have a database function that returns some rows from a sqlite database then stores that in state

rows = await ReturnSelectedSymbolsDB()
this.setState({ symbols: rows })

The array looks something like this

symbols: [{key: "0", symbol:"name1", active: false},{key:"1", symbol:"name2",active: false}]

I have another database function which returns some rows and I wish to add them to symbol so it would look like this. 

symbols: [{key: "0", symbol:"name1", active: false, newKey: newValue},{key:"1", symbol:"name2",active: false, newKey, newValue2}]

The second function will return multiple rows from the database which will be easy to match up with symbols as symbols:symbol will match otherFunction:symbol.

Normally you would just write this like a regular SQL query with a inner join joining the 2 tables together and then just putting the resulting rows in a state variable but I cannot in this case and must build the state variable piece by piece.

Can this be done is regular javascript?

EDIT: Probably wasnt clear but newKey can have different values depending on what the name of the symbol is

Upvotes: 0

Views: 3796

Answers (4)

QuokMoon
QuokMoon

Reputation: 4425

You have to insert your new value into your first function array, there are couples of way can insert object in array either use for loop or array manipulation functions.

var arrOfObj = [{
  key: "0", 
  symbol:"name1", 
  active: false
}, {
  key: "1", 
  symbol:"name1", 
  active: false
}, {
  key: "2", 
  symbol:"name1", 
  active: false
}];

var result = arrOfObj.map(function(o) {
  o.newKey = newValue;
  return o;
})

console.log(result)

Note: I would prefer to go with inner join with two tables to return combine array that not require any array manipulation.

Upvotes: 1

Jaydeep Galani
Jaydeep Galani

Reputation: 4961

Try this,

let symbols = [
  { key: "0", symbol: "name1", active: false },
  { key: "1", symbol: "name2", active: false }
];
let newSymbols = [
  { key: "1", symbol: "name1", newKey: "fdds" },
  { key: "0", symbol: "name2", newKey: "sadav" }
];

mergeArray = (arrayOld, arrayNew) => {
  let output = arrayOld.filter(item => {
    let find = findMatchingItem(arrayNew, item.key);
    item["newKey"] = find.newKey;
    return item;
  });
  return output;
};

findMatchingItem = (array, matchingItemKey) => {
  let output = null;
  array.map(item => {
    if (item.key == matchingItemKey) {
      output = item;
    }
  });
  return output;
};

let newArray = mergeArray(symbols, newSymbols);
console.log(newArray);

I have matched objects using "key" if you want from "symbol" just change "key" to "symbol"

Upvotes: 0

Codesingh
Codesingh

Reputation: 3384

You can create a new util function where you can add new key to all object inside the array.

addKey(symbol) {
   let newArray=[...symbol];
   return newArray.map((ele, i) => {
      return {...ele, newKey: newValue};
   })
}

Happy Coding :)

Upvotes: 2

landesko
landesko

Reputation: 372

You could do something like this if you know the key value corresponding to a given symbol:

for (let i = 0; i < symbols.length; i++){
    symbols[i].newKey = "anyValue"
}

Upvotes: 0

Related Questions