How to create add and subtract buttons to track inventory - button

Question

I've been searching for similar solutions out there but am coming up short so far. Here is what I want to accomplish:
I need to come up with a basic solution to sync inventory quantities at the end of each day. We take physical counts of inventory sold throughout the day but need something to log these changes and share between users. I would like to utilize two buttons (click one to subtract amount of items sold at the end of the day and click one button to add newly received inventory).
This is how my sheet is set up:
Col A: Product Tag
Col B: Product sku
Col C: Amount Sold Today
Col D: Total Inventory Quantity
Col E: Add New Inventory
Column D will be pre-populated with initial inventory counts. At the end of each day, I would like to go down my product list and fill in the amount of each item sold that day in Column C. Once Column C is fully populated, I would like to click the "subtract" button and have Column C subtracted from Column D.
On the other side, once we receive new stock of an item I would like to enter these counts into Column E. Once this column is fully populated, I would like to click the "Add" button and have Column E added to Column D. Ideally once the add or subtract function has been completed, columns C or E will be cleared and ready for the next days entry.
I already have designed my buttons, I just need help coming up with the scripts to accomplish this.

Answer 1

You can use Google Apps Script for this.
If you are unfamiliar, in your particular spreadsheet, go to Tools → Script Editor and then select the Blank Project option.
Then you can write functions like this to achieve what you want!
function subtractSold() {
var sheet = SpreadsheetApp.getActiveSheet();
var c1 = sheet.getRange("C2");
var c2 = sheet.getRange("D2");
while (!c1.isBlank() && !c2.isBlank()){
c2.setValue(c2.getValue() - c1.getValue());
c1.clear();
c1 = c1.offset(1, 0);
c2 = c2.offset(1, 0);
}
}
Basically what the function does is:
Get a reference to the active spreadsheet
Get references to the cells C2 and D2, for the first row of data.
Use a while loop to repeated go through the rows. Terminate when either cell is empty.
In the loop, we get the appropriate values, subtract and set the value back into the cell. Then we clear the cell in column C. We then move both cell references down by one row (the offset method returns a reference to the original cell, but offset by row, column).
Then assign the script to the button image by entering the name of the function (subtractSold in this case) in the "Assign script" option for the button.
I have made an example sheet here (go to File → Make a Copy to try the scripts and see the code): https://docs.google.com/spreadsheets/d/1qIJdTvG0d7ttWAUEov23HY5aLhq5wgv9Tdzk531yhfU/edit?usp=sharing
A bit faster
If you try the sheet above you can see it processes one row at a time, which might get pretty slow when you have a lot of rows. It is probably faster to process the entire column in bulk, but it may be a bit more complicated to understand:
function subtractSoldBulk() {
var sheet = SpreadsheetApp.getActiveSheet();
var maxRows = sheet.getMaxRows();
var soldRange = sheet.getRange(2, 3, maxRows); // row, column, number of rows
var totalRange = sheet.getRange(2, 4, maxRows);
var soldValues = soldRange.getValues();
var totalValues = totalRange.getValues();
for (var row in soldValues) {
var soldCellData = soldValues[row][0];
var totalCellData = totalValues[row][0];
if (soldCellData != "" && totalCellData != "") {
totalValues[row][0] = totalCellData - soldCellData;
soldValues[row][0] = "";
}
}
soldRange.setValues(soldValues);
totalRange.setValues(totalValues);
}
The difference here is that instead of getting one cell, we get one range of cells. The getValues() method then gives us a 2D array of the data in that range. We do the calculations on the two arrays, update the data in the arrays, and then set the values of the ranges based on the array data.
You can find documentation for the methods used above from Google's documentation: https://developers.google.com/apps-script/reference/spreadsheet/sheet