E-mail notification based on cell value. Unable to apply script function for all rows - email

Question

I am using Google sheets and the Google script editor to create a script to automatically send myself an e-mail every time a product quantity goes below the minimum inventory level. Since I have multiple products with different minimum inventory levels I expect to get a series of e-mails, one for each row.
I use one sheet for the actual Inventory data and another sheet that contains information for the script to refer to, such as my email and what message to include in the e-mail.
I succeeded having an e-mail sent collecting data from the first row of the Inventory sheet but I am not being able to apply that for all the following rows.
I tried changing the .getRange("F2") to .getRange("F2:F"), then whenever one of the products goes under the minimum inventory level I get one single e-mail containing the information about all products, regardless of whether their quantity is under the minimum level or not.
The ideal solution would be ONE single e-mail containing all the information about all products that are under the minimum quantity .
Here is a link to my spreadsheet: https://docs.google.com/spreadsheets/d/1ZHmBvi8ZeaDRYq6Qigaw08NUiOwZumPrLnvnka_mgmA/edit?usp=sharing
Current script:
function CheckInventory() {
// Fetch inventory quantity
var InventoryRange = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("Inventory").getRange("F2");
var Inventory = InventoryRange.getValue();
// Fetch minimum quantity
var MinimumQuantityRange = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("Inventory").getRange("D2");
var MinimumQuantity = MinimumQuantityRange.getValue();
// Check Inventory
if (Inventory < MinimumQuantity){
// Fetch email address
var emailRange = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("Notification Rules").getRange("E2");
var emailAddress = emailRange.getValues();
// Fetch email message details.
var detailsRange = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("Notification Rules").getRange("G2");
var details = detailsRange.getValues();
var subjectdetailsRange = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("Notification Rules").getRange("H2");
var subjectdetails = subjectdetailsRange.getValues();
// Send Alert Email.
var message = details;
var subject = subjectdetails;
MailApp.sendEmail(emailAddress, subject, message);
}
}

Answer 1

Update:
As you said in a comment, you want the email to be sent when you edit an inventory cell, and only if this edited inventory quantity is below the corresponding minimum. So here I update my answer accordingly.
First, I guess you have done this already, but because the function uses sendEmail, you will have to grant authorization for it to work. I created a trigger for that. Run this once:
function createEditTrigger() {
var ss = SpreadsheetApp.getActive();
ScriptApp.newTrigger("CheckInventory")
.forSpreadsheet(ss)
.onEdit()
.create();
}
Then, this is the function that will run every time the spreadsheet is edited. To avoid the email to be sent every time the file is edited, we need a condition that checks whether the edited cell is an inventory and that this inventory is below the minimum:
function CheckInventory(e) {
var ss = e.source;
var inventorySheet = ss.getSheetByName("Inventory");
var rowIndex = e.range.getRow();
var columnIndex = e.range.getColumn();
var numCols = 6;
var row = inventorySheet.getRange(rowIndex, 1, 1, numCols).getValues()[0];
var editedInventory = row[5];
var editedMinimum = row[3];
var sheetName = ss.getActiveSheet().getName();
// Checking that: (1) edited cell is an inventory quantity, and (2) Inventory is below minimum
if(editedInventory <= editedMinimum && sheetName == "Inventory" && columnIndex == 6 && rowIndex > 1) {
var inventoryValues = inventorySheet.getDataRange().getValues();
var emailBody = "";
for(var i = 1; i < inventoryValues.length; i++) {
var inventory = inventoryValues[i][5];
var minimum = inventoryValues[i][3];
if(inventory <= minimum) {
var productName = inventoryValues[i][0] + " " + inventoryValues[i][1];
var productUnits = minimum + " " + inventoryValues[i][4];
var messagePart1 = "Inventory for " + productName + " has gone under " + productUnits + ". ";
var messagePart2 = "Organise purchase order. Inventory as of today is: " + inventory + " " + inventoryValues[i][4];
var message = messagePart1.concat(messagePart2);
var newItem = "<p>".concat(message, "</p>");
emailBody += newItem;
}
}
var emailSubject = "Low inventory alert";
var emailAddress = "your-email#your-domain.com";
// Send Alert Email
if(emailBody != "") {
MailApp.sendEmail({
to: emailAddress,
subject: emailSubject,
htmlBody: emailBody
});
}
}
}
As I said in a comment, if you just want to send an email, it doesn't make sense to have many email subjects, so I hardcoded the subject.
Regarding the emails, I assumed you just want an email address to receive the email, so I hardcoded it too. If you want all the different email addresses found in Notifications tab to receive emails regarding all products, a small fix would be needed to this code. Tell me if that's needed for you.
Also, I didn't use your notifications tab at all, I created the message directly using the script. I'm not sure it is that useful to have the sheet "Notification Rules". Much of its info is the same as the one in inventory, and the rest of data (email address, basically) could be easily included there. But whatever suits you.
I hope this is of any help.