我如何使用jsonloader為數組定義架構？

Question

我正在使用Elephantbird項目將json文件加載到Pig。 但是我不確定如何在加載時定義架構。 找不到相同的描述。

數據：

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

碼：

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;

結果：

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

我如何才能給它們正確的架構（整數，字符串，數組，數組），以及如何將數組元素展平為行？

提前致謝

Answer 1

將json數組轉換為元組：

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)};

扁平化一個元組

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