如何使用jsonloader为数组定义模式？

Question

我正在使用elephantbird项目将一个json文件加载到pig中。但我不确定如何在加载时定义模式。没有找到关于相同的描述。

数据：

{"id":22522,"name":"Product1","colors":["Red","Blue"],"sizes":["S","M"]}
{"id":22523,"name":"Product2","colors":["White","Blue"],"sizes":["M"]}

代码：

feed = LOAD '$INPUT' USING com.twitter.elephantbird.pig.load.JsonLoader() AS products_json;

extracted_products = FOREACH feed GENERATE
    products_json#'id' AS id,
    products_json#'name' AS name,
    products_json#'colors' AS colors,
    products_json#'sizes' AS sizes;

describe extracted_products;

结果：

extracted_products: {id: chararray,name: bytearray,colors: bytearray,sizes: bytearray}

如何给它们提供正确的模式(int、string、array、array)，以及如何将数组元素展平为行？

提前感谢

Answer 1

要将json数组转换为tuple：

feed = LOAD '$INPUT' USING com.twitter.elephantbird.pig.load.JsonLoader() AS products_json;

extracted_products = FOREACH feed GENERATE
products_json#'id' AS id:chararray,
products_json#'name' AS name:chararray,
products_json#'colors' AS colors:{t:(i:chararray)},
products_json#'sizes' AS sizes:{t:(i:chararray)};

展平元组

flattened = foreach extracted_products generate id,flatten(colors);