javascript - Azure 分析 UDF

Question

我想知道是否可以使用用户定义的 .js，从流分析中的 Json 字符串中解码 Base64。我可以自由地使用任何 js 函数吗？或者是否有预设数量的函数可以使用。我尝试使用 atob()，但 SAnalytic 告诉我:

Function 'base64decod' resulted in an error: 'ReferenceError: 'atob' is not defined' Stack: ReferenceError: 'atob' is not defined at main (Unknown script code:3:4)

UDF:

function main(arg1) {
var decodData = atob(arg1);
return decodData;
}

查询:

SELECT
      [SystemProperties].[connectionDeviceId], temp, hum, rssi, snr, 
      EventProcessedUtcTime, UDF.base64decod(Body)
INTO
      [intoData]
FROM
      [fromBlob]

JSON 片段:

{
 "EnqueuedTimeUtc": "2019-12-09T12:39:08.3320000Z",
 "Properties": {},
 "SystemProperties": {
   "to": "/devices/device-03/messages/events",
   "connectionDeviceId": "device-03",
   "connectionAuthMethod": "{\"scope\":\"device\",\"type\":\"sas\",\"issuer\":\"iothub\",\"acceptingIpFilterRule\":null}",
  "connectionDeviceGenerationId": "xxxxxxxxx025137526",
  "contentEncoding": "",
  "enqueuedTime": "2019-12-09T12:39:08.3320000Z"
},
 "Body": "eyJ0ZW1wIjoxLjc1LCJodW0iOjYxLjYzLCJyc3NpIjotMTAzLCJzbnIiOjguMn0=",
 "EventProcessedUtcTime": "2019-12-09T12:42:07.9089000Z",
 "PartitionId": 0,
 "BlobName": "measurements/iotc-xxxxxxxxxxxxxxxx/2019/12/09/12/40/01.json",
 "BlobLastModifiedUtcTime": "2019-12-09T12:41:06.0000000Z"
},

非常感谢您的帮助!

Answer 1

根据official document ，恐怕你不能使用任何简单的封装方法，如atob或btoa。您可以尝试一些原创的东西，如下所示:

UDF 代码:

function base64decode(str) {
    var base64DecodeChars = new Array(
    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,
    52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1,
    -1,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,
    15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,
    -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
    41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1);

    var c1, c2, c3, c4;
    var i, len, out;

    len = str.length;
    i = 0;
    out = "";
    while(i < len) {
    /* c1 */
    do {
        c1 = base64DecodeChars[str.charCodeAt(i++) & 0xff];
    } while(i < len && c1 == -1);
    if(c1 == -1)
        break;

    /* c2 */
    do {
        c2 = base64DecodeChars[str.charCodeAt(i++) & 0xff];
    } while(i < len && c2 == -1);
    if(c2 == -1)
        break;

    out += String.fromCharCode((c1 << 2) | ((c2 & 0x30) >> 4));

    /* c3 */
    do {
        c3 = str.charCodeAt(i++) & 0xff;
        if(c3 == 61)
        return out;
        c3 = base64DecodeChars[c3];
    } while(i < len && c3 == -1);
    if(c3 == -1)
        break;

    out += String.fromCharCode(((c2 & 0XF) << 4) | ((c3 & 0x3C) >> 2));

    /* c4 */
    do {
        c4 = str.charCodeAt(i++) & 0xff;
        if(c4 == 61)
        return out;
        c4 = base64DecodeChars[c4];
    } while(i < len && c4 == -1);
    if(c4 == -1)
        break;
    out += String.fromCharCode(((c3 & 0x03) << 6) | c4);
    }
    return out;
}

SQL:

SELECT
      UDF.base64decode(Body)
FROM
      [fromBlob]

输出: