从Firebase检索键数组，“变量在其自身值内使用”

Question

尝试从Firebase获取一系列子键

func getWavePosts() {
    let wavePostRoot = Database.database().reference().child("waves_posts/\(self.waveLabel!)/")

    wavePostRoot.observe(.value , with: {snapshot in

        var tempKeys = [String]()
        for child in snapshot.children {
            let snap = child as! DataSnapshot
            let key = snap.key {
                 tempKeys.append(key as String)
            }
        }
        self.tempNames = tempKeys
})
}

我已经对键之前的值进行了此操作，但没有对键进行操作，附加行是已标记的行。在键初始化下方插入一行将错误更改为“无法推断通用参数'Element'”。任何帮助将不胜感激！

---------不带for循环编辑---------

 let wavePostRoot = Database.database().reference().child("waves_posts/\(self.waveLabel!)/")

    wavePostRoot.observe(.value , with: {snapshot in

        var tempKeys = [String]()

        self.tempNames.append(snapshot.key)

Answer 1

您想进行可选绑定，但是忘记了 $refresh_body = @{ client_id='redacted'; client_secret='redacted'; refresh_token='redacted'; grant_type="refresh_token"; } $refresh_token = Invoke-RestMethod -Uri "https://www.googleapis.com/oauth2/v4/token" -Method POST -Body $refresh_body $access_token = $refresh_token.access_token $title = "Scan.pdf" $description = "scan" $parentfolder = "redacted" #folder ID where to save $inputmime = "application/vnd.google-apps.document" # https://developers.google.com/drive/v2/web/mime-types more on mime types here $togoogle = "S:\Building_Permit_Tool\Working\0\*.pdf" ##The body must be formatted EXACTLY as below. Any extra linebreaks within the boundaries will cause Google to return a 400 error $GUploadBody = @" Content-Type: application/json; charset=UTF-8 { "name": "$title", "parents": [{ "id":"$parentfolder" }], "mimeType": "$inputmime", "description": "$description" } --BOUNDARY Content-Type: application/pdf $togoogle --BOUNDARY-- "@ ## End HTTP Body $GBodySize = ($GUploadBody | Measure-Object -property length -sum).Sum #Calculates the size in bytes of the HTTP POST body, necessary for Content- Length in the request header #Request headers $Guploadheaders = @{"Authorization" = "Bearer $access_token" "Content-type" = 'text/plain; boundary="BOUNDARY"' "Content-Length" = "$GBodySize" } $GUploadURI = "https://www.googleapis.com/upload/drive/v3/files?uploadType=media" $uploadrequest = Invoke-WebRequest -method POST -uri $GUploadURI -body $GUploadBody -Headers $Guploadheaders $uploadrequest 关键字。另外，我认为您想检查if是否为snap.key

类型

String