Question

30

How to use array-contains operator with an array of objects in Firestore?

rated 0 times [ 35] [ 5] / answers: 1 / hits: 6113 / 3 Years ago, wed, june 30, 2021, 12:00:00

So, i want to query some data from firestore.

this is my data structure

so, the collection is Modules, then i now have 2 documents but it will be 75 or something. Then in that document i want to get the specific document which has a specific LessonId (In this example '2')
How do i query this?

this is wat i tries but it's not working for me

    async function getModuleData() {

        let ModuleData = await firebase

            .firestore()

            .collection('Modules')

            .where('Lessons', 'array-contains', {LessonId: 2})

            .get()

            .then(snapshot => {

                snapshot.forEach(doc => {

                    console.log(doc.data())

                })

            });

   } getModuleData()

when i do this

    async function getModuleData() {

        let ModuleData = await firebase

            .firestore()

            .collection('Modules')

            .where('Title', '==', 'Leven vanuit verlossing')

            .get()

            .then(snapshot => {

                snapshot.forEach(doc => {

                    console.log(doc.data())

                })

            });

   } getModuleData()

it just works so it's something with my where statement i guess?

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anayaashleyh

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answered 3 Years ago elians · Accepted Answer

To use array-contains with an array of objects, you need to pass the complete object you are looking for in that array.

For example,

const lessonObj = {

  Title: "Leven vanuit verlossing",

  Description: "the desc",

  ...allTheOtherFieldsAsIs

}

firebase.firestore().collection("Modules").where("Lessons", "array-contains", lessonObj)

You should ideally use a sub-collection to store lessons in a module. Then you can easily query lessons using the following query:

const db = firebase.firestore()



const lessonsSnapshot = await db.collection("Modules")

                          .doc("moduleID")

                          .collection("Lessons")

                          .where("Title", "==", "Leven vanuit verlossing")

                          .get()



console.log(lessonsSnapshot.docs[0].data())