Firestore: Update fields in nested objects

Question

How can one update fields in a document's nested object? The documentation indicated dot notation but how do you achieve the update with a variable as the object name?

Structure is like: collection("fruits").doc("as867f56asd")

name: "banana"
abc-variable: 
    description:"blah"
    qty: 1

I want to update document as867f56asd's abc-variable.qty = 2

My JavaScript requires the use of a variable for the object name.

I can't figure out bracket notation for the update. Is .set{merge:true} req'd?

Here is the code I've tried so far (rough paste):

qty = evt.target.value;
//create a string
var obj = firebase.firestore.FieldPath(item).quantity;
//str = item + '.quantity';
//obj[str] = qty;
// var myUpdate = {};
// myUpdate['${item}.quantity'] = qty;
//var obj = [item]["quantity:"] = qty;
console.log("item is " + item);
//var obj = {"'" + item + "'.quantity" : qty};
//obj[item]["quantity"] = qty;
console.log("qty is " + qty);
orderRef.update (
    {obj:2}
    //{"quantity":qty}
    //[item + '.quantity']: qty
    //[`favorites.${key}.color`] = true
    // ['${item}.quantity'] : qty
    //[`hello.${world}`]:
    //{[objname]}.value = 'value';
    //['favorites.' + key + '.color']: true
    //[item]["quantity"] = qty // err:reqd 2 args
    //item["quantity"] = qty
    //"favorites.color": "Red"
    //{"`item`.quantity": qty}
    //{"quantity":qty}
)

Hey Ron. Can you show the code that you tried? I think yuo're looking for something like values[abc-variable+".qty"] = 2, but it's easier to answer if I see what you've done already. — Frank van Puffelen
– Frank van Puffelen, Commented Sep 8, 2018 at 1:06
inside the .update( IDE says values is not defined. If I wrap it in {} it says Unexpected token [. If I declare values = {} prior to the update, the IDE takes it and it passes linting but browser console throws error Uncaught TypeError: Cannot read property 'quantity' of undefined Doing: orderRef.update (values[item+".quantity"] = qty) — Ronnie Smith
– Ronnie Smith, Commented Sep 8, 2018 at 1:16
@FrankvanPuffelen It seems like I would need to nail a type of reference to the field (which is an object) and then from there, update a specific property. FieldPath or even defining a reference using URLencoding \fruits\abc-123doc\obj-field-var but I can't figure it out. I bout to give up and just re-write the whole document to update a single field. I know that works... — Ronnie Smith
– Ronnie Smith, Commented Sep 8, 2018 at 1:23
This myUpdate['${item}.quantity'] = qty; should probably be myUpdate[`${item}.quantity`] = qty;. So with backticks around the string, since that's the JavaScript syntax for string interpolation. — Frank van Puffelen
– Frank van Puffelen, Commented Sep 8, 2018 at 4:36

Tyler McGinnis · Accepted Answer · 2019-01-02 02:14:30Z

13

If the update you're trying to do:

let qty = 2
orderRef.update({"abc-variable.qty": qty});

But then where abc-variable is the value of a variable, you would do:

let qty = 2
let variable = "abc-variable";
var values = {};
values[variable] = qty;
orderRef.update(values);

Update

This code updates only the favorites:

var variableObjectName = "favorites";
var qty = Date.now(); // just so it changes every time we run
var field = {quantity:qty};
var obj = {};
obj[variableObjectName] = field; 
ref.update(obj);

It does not remove any other properties on the document.

Update 2

To update a single field in a nested objected, use . to address the field:

ref.update({ "favorites.quantity": Date.now() });

See the documentation on how to update fields in nested objects.

Update 3

To perform a deep update of a field whose name is stored in a variable:

var name = "favorites";
var update = {};
update[name+".quantity"] = Date.now();
ref.update(update);

Once again shown in: https://jsbin.com/wileqo/edit?js,console

edited Jan 2, 2019 at 2:14

Tyler McGinnis

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answered Sep 8, 2018 at 4:42

Frank van Puffelen

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6 Comments

Ronnie Smith Over a year ago

I challenge you to try to .update a single field of an object stored in a Firestore document where a variable is used as the stored object's name. If you can do it, I'll mail you [anyone] a free hightechtele.com BIC lighter. srsly.

Ronnie Smith Over a year ago

I sincerely appreciate the help. Notice how the other object properties are deleted after the .update? See updated jsbin -> jsbin.com/decizubuyi/edit?js,console ...could u make this work, just want to update quantity property only and leave other properties alone.

Frank van Puffelen Over a year ago

Sorry Ron, I can't reproduce what you're saying. The only time my entire document was overwritten was when you called ref.set() in your code. Once I updated your code in jsbin.com/xibodoc/1/edit?js,console to remove the set() it maintains all other fields, no matter how often I call update().

Ronnie Smith Over a year ago

not the entire document, the entire nested object. Updating a single property of a nested object (without having the other nested object's properties deleted) is the issue/problem. Notice the document in my jsbin included a nested object with 2 properties, name and quantity. Yours shows a nested object with a single property.

Frank van Puffelen Over a year ago

Ah, I get it now. That quite simple: ref.update({ "favorites.quantity ": Date.now() }). See the documentation on how to update fields in nested objects.

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