不一致JSON模式的Spark数据猜测

Question

尝试使用Spark1.4.1数据文件读取JSON文件并在其中导航。似乎猜到的模式不正确。

JSON文件是：

{
    "FILE": {
        "TUPLE_CLI": [{
            "ID_CLI": "C3-00000004",
            "TUPLE_ABO": [{
                "ID_ABO": "T0630000000000004",
                "TUPLE_CRA": {
                    "CRA": "T070000550330",
                    "EFF": "Success"
                },
                "TITRE_ABO": ["Mr",
                "OOESGUCKDO"],
                "DATNAISS": "1949-02-05"
            },
            {
                "ID_ABO": "T0630000000100004",
                "TUPLE_CRA": [{
                    "CRA": "T070000080280",
                    "EFF": "Success"
                },
                {
                    "CRA": "T070010770366",
                    "EFF": "Failed"
                }],
                "TITRE_ABO": ["Mrs",
                "NP"],
                "DATNAISS": "1970-02-05"
            }]
        },
        {
            "ID_CLI": "C3-00000005",
            "TUPLE_ABO": [{
                "ID_ABO": "T0630000000000005",
                "TUPLE_CRA": [{
                    "CRA": "T070000200512",
                    "EFF": "Success"
                },
                {
                    "CRA": "T070010410078",
                    "EFF": "Success"
                }],
                "TITRE_ABO": ["Miss",
                "OB"],
                "DATNAISS": "1926-11-22"
            }]
        }]
    }
}

星星之火代码是：

val j = sqlContext.read.json("/user/arthur/test.json")
j.printSchema

结果是：

root
 |-- FILE: struct (nullable = true)
 |    |-- TUPLE_CLI: array (nullable = true)
 |    |    |-- element: struct (containsNull = true)
 |    |    |    |-- ID_CLI: string (nullable = true)
 |    |    |    |-- TUPLE_ABO: array (nullable = true)
 |    |    |    |    |-- element: struct (containsNull = true)
 |    |    |    |    |    |-- DATNAISS: string (nullable = true)
 |    |    |    |    |    |-- ID_ABO: string (nullable = true)
 |    |    |    |    |    |-- TITRE_ABO: array (nullable = true)
 |    |    |    |    |    |    |-- element: string (containsNull = true)
 |    |    |    |    |    |-- TUPLE_CRA: string (nullable = true)

很明显，TUPLE_CRA是一个数组。我不明白为什么没猜到。在我看来，推断模式应该是：

root
 |-- FILE: struct (nullable = true)
 |    |-- TUPLE_CLI: array (nullable = true)
 |    |    |-- element: struct (containsNull = true)
 |    |    |    |-- ID_CLI: string (nullable = true)
 |    |    |    |-- TUPLE_ABO: array (nullable = true)
 |    |    |    |    |-- element: struct (containsNull = true)
 |    |    |    |    |    |-- DATNAISS: string (nullable = true)
 |    |    |    |    |    |-- ID_ABO: string (nullable = true)
 |    |    |    |    |    |-- TITRE_ABO: array (nullable = true)
 |    |    |    |    |    |    |-- element: string (containsNull = true)
 |    |    |    |    |    |-- TUPLE_CRA: array (nullable = true)
 |    |    |    |    |    |    |-- element: struct (containsNull = true)
 |    |    |    |    |    |    |    |-- CRA: string (nullable = true)
 |    |    |    |    |    |    |    |-- EFF: string (nullable = true)

有人有解释吗？如果JSON模式要复杂得多，是否有一种方法可以轻松地告诉Spark实际的模式是什么？

Answer 1

好吧，终于明白JSON不是预期的了。您会注意到，第一个TUPLE_CRA是一个没有方括号的元素[]。其他的TUPLE_CRA是带有括号和内部几个元素的数组。这就是为什么星火无法准确地猜出结构的原因。所以这个问题来自于这个JSON的生成。我需要修改它，使每个TUPLE_CRA都成为一个数组，即使其中只有一个元素。