How to update one field in Array of Json Objects?

Question

I am doing reactjs so I need to update a field in away that will trigger state change.

I have this payload(only show 1 but it is an array of many)

    [
                {
                    id: 1,
                    name: "Fridge2",
                    selected: true,
                    sharingId: 'ae9b9566-3b5c-4772-a0a1-07ed8b354b8f',
                    sharingWith: ["jim@hotmail.com", "jim2@hotmail.com"],
                    storageItems: [
                        {
                            id: 'ae9b9564-3b5c-2711-a421-07ed8b354b8f',
                            name: 'Chicken Breats',
                            qty: 10,
                            expiresOn: '3',
                            category: 'Meat',
                            categoryId: 'BDEC0494-B16E-411B-8E32-A64A00E943F8',
                            unitType: 'Pieces',
                            unitTypeId: '63CDB076-C20D-4DC5-A181-A64A00E94409'
                        },
                        {
                            id: 'ae9b9566-3b5c-2711-a4a1-07ed8b354b8f',
                            name: 'Chicken Breats2',
                            qty: 10,
                            expiresOn: '0',
                            category: 'Meat',
                            categoryId: 'BDEC0494-B16E-411B-8E32-A64A00E943F8',
                            unitType: 'Pieces',
                            unitTypeId: '63CDB076-C20D-4DC5-A181-A64A00E94409'
                        },
                        {
                            id: 'ae9b9566-3b5c-2712-a0a1-07ed8b354b8f',
                            name: 'Chicken Breats3',
                            qty: 10,
                            expiresOn: '4',
                            category: 'Meat',
                            categoryId: 'BDEC0494-B16E-411B-8E32-A64A00E943F8',
                            unitType: 'Pieces',
                            unitTypeId: '63CDB076-C20D-4DC5-A181-A64A00E94409'
                        }
                    ]
                }
]

I want to find storageItem that matches the an ID 'ae9b9564-3b5c-2711-a421-07ed8b354b8f' (first one in the array)

I then want to take it out update the a field(say qty) stick it back in and have a state change happen.

This was my very bad 1st attemp at it. It does not work

case actions.STORAGE_ITEM_USED: {
            var foundItem = state.selectedStorage.storageItems.filter(i => i.id == action.payload);
            var newQty = foundItem[0].qty - 1;
            foundItem[0].qty = newQty;
            var nonChangedStorageItem = state.selectedStorage.storageItems.filter(i => i.id != action.payload);

            var allItems = nonChangedStorageItem.concat(foundItem);
            state.selectedStorage.storageItems = allItems;

            return {
                selectedStorage: state.selectedStorage,
            }

        }

Edit

I have this now but I see a new possible answer that I will checkout

var newSelectedStorage =  Object.assign({} , state.selectedStorage);

   var foundItem = newSelectedStorage.storageItems.filter(x => x.id == action.payload);
   foundItem[0].qty = foundItem[0].qty - 1;

   var nonChangedItems = newSelectedStorage.storageItems.filter(x => x.id != action.payload);

   newSelectedStorage.storageItems = nonChangedItems.concat(foundItem);

webpack.config.js

module.exports = {
  devtool: 'inline-source-map',
  entry: "./app/index.js",
  output: {
    path: __dirname + '/dist',
    filename: "bundle.js"
  },
  devServer: {
    contentBase: "./app",
    inline: true,
    port: 3333
  },
  module: {
    loaders: [
      {
        test: /\.jsx?$/,
        loader: 'babel-loader',
        exclude: /node_modules/,
        query: {
          presets: ['es2015', 'react']
        }
      },
      {
        test: /\.scss$/,
        loaders: ['style', 'css', 'sass']
      },
      {
        test: /\.woff($|\?)|\.woff2($|\?)|\.ttf($|\?)|\.eot($|\?)|\.svg($|\?)/,
        loader: 'url-loader'
      }
    ]
  },
   externals: {
    jquery: 'jQuery'
  },
} 

Answer 1

By the looks of it, you're trying to decrease the qty property on any matching objects in state.selectedStorage.storageItems.

Since Redux needs a whole new object, we can use ES6's object spread operators to return a new object with most of the values already filled in.

case actions.STORAGE_ITEM_USED:
    return {
        ...state,
        selectedStorage: state.selectedStorage.storageItems.map(i => {
            if (i.id != action.payload) return i;
            return {
                ...i,
                qty: i.qty - 1
            }
        })
    }

I can't test if this works, but the idea is that we are returning a new object, copying existing state objects, then overwriting selectedStorage with a new array where only items whose ids matching action.payload's qty properties are decreased.