I have a collection of items, and within that a Category field that contains 'Breakfast,Lunch,Dinner'

How do I sort these items (index) by Breakfast then Lunch and then Dinner?

Am currently using the following code which is a simple sort alphabetically:

.orderBy("Category", "asc")
.orderBy("Name", "asc")

CodePudding user response：

I honestly don't think there is a way in firebase to create custom sorting schemes. A solution could be to use a Cloud Function. Or you can do this (although I realize it's not very elegant):

let docs = [];
        firebase.firestore().collection('...').where("category","==","breakfast").orderBy("name").get()
        .then((snapshotBreakfast) => {
            snapshotBreakfast.forEach(doc => docs.push(doc.data()));
            firebase.firestore().collection('...').where("category","==","lunch").orderBy("name").get()
            .then((snapshotLunch) => {
                snapshotLunch.forEach(doc => docs.push(doc.data()));
                firebase.firestore().collection('...').where("category","==","dinner").orderBy("name").get()
                .then((snapshotDinner) => {
                    snapshotDinner.forEach(doc => docs.push(doc.data()));
                })
            })
        })

I haven't tested it, but it should work. However I think the idea behind this code is clear.

CodePudding user response：

As shown in the Firebase documentation on data types, string fields are order lexicographically. There is no way to change this.

Two common options:

1. Store the meal category as a numeric value in the order of your choosing, so 1 being breakfast, 2 being lunch, and 3 being dinner.
2. Give the meal category a numeric prefix to determine its order, so 1 - breakfast, 2 - lunch, 3 - dinner.