Firestore 应用 GO 中的阵列位置

Question

I have these structs

type Notification struct {
    Content []NotificationContent `json:"content"`
    CreatedAt time.Time `json:"createdAt"`
}

type NotificationContent struct {
    Language string `json:"language"`
    Title string `json:"title"`
}

And I'm trying to query my Firestore database to fetch any notification that have a specific Language .

Using

query := client.Collection("notifications").Where("Content.Language", "==", "en")

or

query := client.Collection("notifications").Where("Content.Language", "in", [1]string{"en"})

always return null.

Using nodejs I could also use

client.Collection("notifications").where("Content", "array-contains", { Language: "en" })

but I have no idea how to translate to GO

Thanks for any input!

EDIT Data structure and sample data as requested

Answer 1

As shown in this answer :

The array-contains operations check if an array contains a specific (complete) value. It can't check if an array of objects contains an item with a specific value for a property.

Therefore, that is why the query you are trying to do won't work.

---

From the test I have made, the following query

query := client.Collection("notifications").Where("Content", "array-contains", map[string]string{"Language":"en"}).Documents(ctx)

will return no values, as the array-contains filter is looking for an entire object. But a similar query (workaround) is possible as shown on this other answer :

However, there is a possible workaround: it is actually possible to query for the entire object

In your case, the query would be as follows:

query := client.Collection("notifications").Where("Content", "array-contains", map[string]string{"Language":"en", "Title":"Foo Bar"}).Documents(ctx)

As you can see in the question , the data structure is similar to yours and the case of use is the same as yours. So, the recommendation made in this answer would fit your problem:

The only way to do your query, is to add an additional field to your document with just the value you want to query existence on. So for example: partyMemberNames: ["John Travolta", "Olivia Newton"] .