CODEWITHSUNDEEP
javascriptjqueryarrays
varun kumar
varun kumar

Reputation: 115

Updating multi-dimensional array with new key,value object if exists or create new

I have an array which is

    var mycart = [{"id":"1","quantity":"10"},{"id":"6","quantity":"20"},{"id":"3","quantity":"30"},{"id":"4","quantity":"40"}];

   //new id's which should be updated
   var newid = "6";
   var newquantity = "5";

Every-time on cart update i want to update the id and value,if id exists i need to update quantity if doesn't i have to create a new object of id,quantity. Now,i am adding newid which is 6,as you can see id=6 exist in array so it should just update like this - 

for(var x=0; x < mycart.length; x++){
    if(mycart[x].id == newid ){
        var tmpq = mycart[x].quantity;
        mycart[x].quantity = parseInt(tmpq) + parseInt(q);
    }
    else{
        alert(mycart[x].id+' = this is not what you are searching');
    }
}

now output is :

var mycart = [{"id":"1","quantity":"10"},{"id":"6","quantity":"25"},{"id":"3","quantity":"30"},{"id":"4","quantity":"40"}];

Now i need help to create new object,if that id doesn't exist in the mycart array.

 //new id's which should be created
    var newid = "2";
    var newquantity = "15";
    var temparr = new Array();
    var tmpobj ={}; 
      tmpobj["id"]= newid ;
      tmpobj["quantity"] = newquantity ;
      temparr.push(tmpobj);
    mycart.push(temparr);

within the for loop it will create mycart.length times,then i have to filter with $unique() jQuery API which is bad method to follow.

All i need is to create new object with id:value,quantity:value if it doesn't exists,if it exists then just update. Update part working,create part not able to,

Upvotes: 1

Views: 2004

Answers (4)

Armel Larcier
Armel Larcier

Reputation: 16027

Since there is no reason for the array to contain multiple objects with the same id, I suggest you use an object as the root of the variable, using the id as an array key (+ prefix to avoid confusions) :

var mycart = {"item_1":{"id":"1","quantity":"10"},"item_6":{"id":"6","quantity":"20"},...};

This way you can set/get quantity with mycart["item_"+id].quantity

so you can update it like that :

function updateQuantity(id, quantity){
    if(!mycart["item_"+id]){
        // create item in cart
        mycart["item_"+id] = {"id":id};
    }
    // update quantity
    mycart["item_"+id].quantity = quantity;
}

Upvotes: 0

belph
belph

Reputation: 362

What about something like this?

updateCart = function(newid,newquantity,cart){
    for(var x=0; x < mycart.length; x++){
        if(mycart[x].id == newid ){
            var tmpq = cart[x].quantity;
            cart[x].quantity = parseInt(tmpq) + parseInt(newquantity);
            return;
        }
        else{
            alert(mycart[x].id+' = this is not what you are searching');
        }
    }
    cart.push({"id":newid,"quantity":newquantity});
    return;
};

This avoids any 'flag' variables, which IMHO is nice. You could then call it like so:

updateCart("6","5",mycart); //[..{"id":"6","quantity":"25"}..]
updateCart("10","7",mycart); //[..{"id":"10","quantity":"7"}](new array member)
updateCart("1","5",mycart); //[{"id":"1","quantity":"15"}...]

I must agree with the others, though, when they say that you might want to use some sort of key so you don't have to iterate through the array each time.

Upvotes: 1

Barmar
Barmar

Reputation: 781088

Use a variable to detect if you found an old item:

var found = false;
for(var x=0; x < mycart.length; x++){
    if(mycart[x].id == newid ){
        var tmpq = mycart[x].quantity;
        mycart[x].quantity = parseInt(tmpq) + parseInt(q);
        found = true;
        break;
    }
}
if (!found) {
    mycart.push ({ id: newid, quantity: newquantity });
}

It would be simpler if you made mycart an object whose keys are the IDs, so you wouldn't have to do a linear search. It would be like this:

var mycart = {
    "1": { quantity: 10 },
    "6": { quantity: 20 },
    ...
};

Then your code would be:

if (mycart.hasOwnProperty(newid)) {
    mycart[newid] += newquantity;
} else {
    mycart[newid] = { quantity: newquantity };
}

Upvotes: 2

Graham S.
Graham S.

Reputation: 1540

To create a new item, I would do:

var match = false;

for (var x = 0; x < mycart.length; x++) {
    var id = mycart[x].id;

    //If there's a match, then item already exists
    if (id === newid) {
        //Update it
        var tmpq = mycart[x].quantity;
        mycart[x].quantity = parseInt(tmpq) + parseInt(q);  //I'm not sure what q is, but I will leave it since you said it works in your code
        match = true;
    }
}

//If no match found, create new
if (!match) {
    var newItem = {};
    newItem.id = newid;
    newItem.quantity = newquantity;
    mycart.push(newItem);
}

Upvotes: 0

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