json - 'NSInvalidArgumentException'，原因 : 'Invalid number value (infinite) in JSON write'

Question

我想要做的是:让用户对商店进行评分，然后更新 Firebase 中的 storeRate 值。

点击 POST 后，出现错误:

'NSInvalidArgumentException', reason: 'Invalid number value (infinite) in JSON write'

//Initialize Variables
var storeRateIni = 0.0
var reviewCount = 0.0
var receivedId = 1             //receive storeId from parent View Controller

refStore = Database.database().reference().child("stores")
refUpdate = Database.database().reference().child("stores").child(String(receivedId))

refStore.observe(DataEventType.value, with: {(snapshot) in
    if snapshot.childrenCount > 0{
        for store in snapshot.children.allObjects as! [DataSnapshot]{
            let storeObject = store.value as? [String: AnyObject]
            let storeId = storeObject?["storeId"] as! Int
            if (storeId == self.receivedId) {
                //Get value store in Firebase
                let storeRate = storeObject?["storeRate"] as! Double
                let storeReviewCount = storeObject?["storeReviewsCount"] as! Double
                //Do the calculation
                let storeRateUpdate = (storeRate + self.userRate.rating) / storeReviewCount
                //Update to Firebase
                self.reviewCount = storeReviewCount + 1
                self.storeRateIni = storeRateUpdate
                self.refUpdate.updateChildValues(["storeRate": self.storeRateIni])                     
                self.refUpdate.updateChildValues(["storeReviewsCount": self.reviewCount])                         
}}}})

Answer 1

这一行，

let storeRateUpdate = (storeRate + self.userRate.rating) / storeReviewCount

当 storeReviewCount == 0.0 时生成 Double.inifinity，这在 JSON 中无法表示。

您可能需要将 storeReviewCount == 0.0 的情况与其他情况分开处理。

例如:

let storeRateUpdate = storeReviewCount == 0.0
    ? 0.0
    : (storeRate + self.userRate.rating) / storeReviewCount