Question 289722 in Firebase Question posted in
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Firebase – Python firestore query for nested fields

I am filtering documents from Firestore in Python from the collection named "students". I am using a Pydantic model for Student that includes a ListField for locations with the Location model and in that location model i am having the id field. Despite having the document in my database for the location id = 1234456, when executing the query below, I am getting an empty list ([]):

query = db.collection("students").where("locations.id", "==", "1234456").get()

Below is my single document structure

{
    name: "tom"
    roll_no: "13024578"
    age: 24
    locations: [
    {
       "id": "1234456",
       "place": "England"
    },
    {
       "id": "432432",
       "place": "Canada"
    }
}
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2

Answers


  1. 0

    You query is assuming locations is a map, whereas your document’s data shows it is a table. Hence you get nothing back.

    What are you trying to do? Get all students which have a given location’s id among all their locations?
    For this you will have to change your document structure:

    1. Create a sub-collection locations under student with each document being a location {id, place}
    2. Make a collection group query on locations specifyng the id. You will get a list of locations document back
    3. You can deduce the students’id from the previous result, you can then retrieve each student’s data as needed
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  2. 0

    This condition in your query:

    .where("locations.id", "==", "1234456")

    Matches a JSON structure that looks (exactly) like this:

    "locations": {
  "id": "1234456"
}

    And since you don’t have that JSON structure in your document, it doesn’t match the query.

    What you seem to be trying to do is to perform a partial match of an item in an array. That’s not possible with Firestore though. Operators such as == and in look for complete matches, not for partial matches.

    To allow the use-case, add an additional array field to the document with just the location IDs:

    locationIDs: [ "1234456", "432432" ]

    Now you can query that field to find the documents with the location ID you want:

    query = db.collection("students").where("locationIDs", "array-contains", "1234456").get()
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