Question

我浏览过网页和论坛，从json文件中下载数据，但我的脚本不起作用。我在下载费率对象列表时遇到问题。有人可以帮忙吗？我找不到错。

{"table":"C","no":"195/C/NBP/2016","tradingDate":"2016-10-06","effectiveDate":"2016-10-07","rates":
[
{"currency":"dolar amerykaĹ„ski","code":"USD","bid":3.8011,"ask":3.8779},
{"currency":"dolar australijski","code":"AUD","bid":2.8768,"ask":2.935},
{"currency":"dolar kanadyjski","code":"CAD","bid":2.8759,"ask":2.9339},
{"currency":"euro","code":"EUR","bid":4.2493,"ask":4.3351},
{"currency":"forint (WÄ™gry)","code":"HUF","bid":0.013927,"ask":0.014209},
{"currency":"frank szwajcarski","code":"CHF","bid":3.8822,"ask":3.9606},
{"currency":"funt szterling","code":"GBP","bid":4.8053,"ask":4.9023},
{"currency":"jen (Japonia)","code":"JPY","bid":0.036558,"ask":0.037296},
{"currency":"korona czeska","code":"CZK","bid":0.1573,"ask":0.1605},
{"currency":"korona duĹ„ska","code":"DKK","bid":0.571,"ask":0.5826},
{"currency":"korona norweska","code":"NOK","bid":0.473,"ask":0.4826},
{"currency":"korona szwedzka","code":"SEK","bid":0.4408,"ask":0.4498},
{"currency":"SDR (MFW)","code":"XDR","bid":5.3142,"ask":5.4216}
],
"EventProcessedUtcTime":"2016-10-09T10:48:41.6338718Z","PartitionId":1,"EventEnqueuedUtcTime":"2016-10-09T10:48:42.6170000Z"}

这是我在sql中的脚本。

@trial =
    EXTRACT jsonString string
    FROM @"adl://kamilsepin.azuredatalakestore.net/ExchangeRates/2016/10/09/10_0_c60d8b8895b047c896ce67d19df3cdb2.json"
    USING Extractors.Text(delimiter:'\b', quoting:false);

@json =
    SELECT Microsoft.Analytics.Samples.Formats.Json.JsonFunctions.JsonTuple(jsonString) AS rec
    FROM @trial;

@columnized =
    SELECT
            rec["table"]AS table,
            rec["no"]AS no,
            rec["tradingDate"]AS tradingDate,
            rec["effectiveDate"]AS effectiveDate,
            rec["rates"]AS rates
    FROM @json;
@rateslist =
    SELECT
        table, no, tradingDate, effectiveDate,
        Microsoft.Analytics.Samples.Formats.Json.JsonFunctions.JsonTuple(rates) AS recl
        FROM @columnized;
@selectrates =
    SELECT
    recl["currency"]AS currency,
    recl["code"]AS code,
    recl["bid"]AS bid,
    recl["ask"]AS ask
    FROM @rateslist;

OUTPUT @selectrates 
    TO "adl://kamilsepin.azuredatalakestore.net/datastreamanalitics/ExchangeRates.tsv"
USING Outputters.Tsv();

Answer 1

您需要查看JSON的结构并确定您要在JSON中构建要映射到相关行的第一条路径。在您的情况下，您实际上只对每个数组项需要一行的速率数组感兴趣。

因此，您将JSONExtractor与JSONPath一起使用，每个数组元素为您提供一行（例如rates[*]），然后对其每个字段进行投影。

这是代码（路径略有变化）：

REFERENCE ASSEMBLY JSONBlog.[Newtonsoft.Json];
REFERENCE ASSEMBLY JSONBlog.[Microsoft.Analytics.Samples.Formats]; 

@selectrates =
    EXTRACT currency string, code string, bid decimal, ask decimal
    FROM @"/Temp/rates.json"
    USING new Microsoft.Analytics.Samples.Formats.Json.JsonExtractor("rates[*]");

OUTPUT @selectrates 
TO "/Temp/ExchangeRates.tsv"
USING Outputters.Tsv();

U-sql在json数组中调用数据

1 个答案: