如何基于值访问JSON对象中的特定项目？

Question

I'm having a bit of trouble getting the information I want out of a set of data (see below). Essentially, I need to get the fuel price for each different type of fuel. Originally I was working off the assumption that each item in the data had all 4 types of fuel, so if I wanted the diesel price, I could just say data.locations[i].fuelTypes[3].price . However, let's say a store doesn't have Premium gas - then diesel would be located at fuelTypes[2] .

Is there a way to look up the item in the fuelTypes array based on its description? Right now the only thing I can think of would be to iterate over everything in the fuelTypes array and say

if (data.locations[i].fuelTypes[j].description == 'Diesel') {
    gasPrice = data.locations[i].fuelTypes[j].price;
}

But this seems like it would be inefficient over a large number of records.

Here's a simplified version of the data I'm working with.

var data = {
    "locations": [
        {
            "name": "Store 1",
            "fuelTypes": [
                {
                    "description": "Unleaded",
                    "price": "1.00",
                    "currency": "USD"
                },
                {
                    "description": "Plus",
                    "price": "2.00",
                    "currency": "USD"
                },
                {
                    "description": "Premium",
                    "price": "3.00",
                    "currency": "USD"
                },
                {
                    "description": "Diesel",
                    "price": "4.00",
                    "currency": "USD"
                }
                ]
        },
        {
            "name": "Store 2",
            "fuelTypes": [
                {
                    "description": "Unleaded",
                    "price": "1.00",
                    "currency": "USD"
                },
                {
                    "description": "Plus",
                    "price": "2.00",
                    "currency": "USD"
                },
                {
                    "description": "Premium",
                    "price": "3.00",
                    "currency": "USD"
                },
                {
                    "description": "Diesel",
                    "price": "4.00",
                    "currency": "USD"
                }
                ]
        }
        ]
};

Answer 1

Another approach, since it hasn't been mentioned is to use JSON path.

$..fuelTypes[?(@.description=='Diesel')]

Would return:

[{
    "description": "Diesel",
    "price": "4.00",
    "currency": "USD"
},
{
    "description": "Diesel",
    "price": "4.00",
    "currency": "USD"
}]

Answer 2

If I understand correctly, the essential problem is that you need to convert your data from being indexed to being key=>value.

If you had a function like this:

function toKeyValue(fuelTypesArray) {
    ob = {};
    for (var i = 0; i < fuelTypesArray.length; i++) {
        ob[fuelTypesArray[i].description] = {
            price: fuelTypesArray[i].price,
            currency: fuelTypesArray[i].currency
        };
    }
    return ob;
}

Then instead of accessing Diesel unreliably like so:

data.locations[i].fuelTypes[3].price

You could use

toKeyValue(data.locations[i].fuelTypes)["Diesel"].price