arrays - 我如何使用 jsonloader 为数组定义模式？

Question

我正在使用大象鸟项目将 json 文件加载到猪。但我不确定如何在加载时定义架构。没有找到相同的描述。

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}

我如何为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？

提前致谢

Answer 1

将 json 数组转换为元组：

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);