在firebase中查询列表 [英] Query over list in firebase

问题描述

我为Firebase使用了以下自定义模型，我需要查询带有特定标签的城市，我尝试了以下代码，但没有用:(

I've the below custom model for firebase, I need to query for the cities with specific tags, I tried the below code but did not work :(

data class City(
        val name: String,
        val state: String?,
        val country: String,
        val capital: Boolean,
        val population: Long,
        val tags : List<String>
)

val sf = City("San Francisco", "CA", "USA",false,
            860000, listOf("tag 1", "tag 2", "tag 3"))

var cities = db.collection("cities")
cities.document("SF").set(sf)

val tags = "(tag 1)|(tag 5)".toRegex()
db.collection("cities")
            .whereEqualTo("name",tags)  // This is wrong 
            .get()
            .addOnCompleteListener { task ->
                if (task.isSuccessful) {
                    for (document in task.result) {
                        Log.d(TAG, document.id + " => " + document.data)
                    }
                } else {
                    Log.d(TAG, "Error getting documents: ", task.exception)
                }
            }

推荐答案

Firestore查询仅支持相等和范围运算.他们不支持正则表达式.您将必须执行两个查询，然后在客户端上合并结果.

Firestore queries only support equality and range operations. They don't support regular expressions. You will have to perform two queries and merge the result on the client.

请参阅:

• 如何在逻辑上执行复合查询还是在Cloud Firestore中?
• 跨多个字段进行相同值的Firestore查询

• How to perform compound queries with logical OR in Cloud Firestore?
• Firestore Query Across Multiple Fields for Same Value

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