Kettle解析JSON錯誤,We MUST have the same number of values for all paths,We can not find and data with path [$.

最近公司要從聚石塔上抽取數據，其中有JSON格式數據，所以學習一下Kettle解析JSON,碰到小小問題，記錄一下：

（1）

2015/07/15 15:22:48 - trade_detail.0 - ERROR (version 5.4.0.1-130, build 1 from 2015-06-14_12-34-55 by buildguy) : Unexpected Error : org.pentaho.di.core.exception.KettleException:
2015/07/15 15:22:48 - trade_detail.0 - The data structure is not the same inside the resource! We found 2 values for json path [$..title], which is different that the number returned for path [$..buyer_alipay_no] (1 values). We MUST have the same number of values for all paths.
2015/07/15 15:22:48 - trade_detail.0 - ERROR (version 5.4.0.1-130, build 1 from 2015-06-14_12-34-55 by buildguy) : org.pentaho.di.core.exception.KettleException:
2015/07/15 15:22:48 - trade_detail.0 - The data structure is not the same inside the resource! We found 2 values for json path [$..title], which is different that the number returned for path [$..buyer_alipay_no] (1 values). We MUST have the same number of values for all paths.
2015/07/15 15:22:48 - trade_detail.0 -

原因是由於JSON嵌套內的對象還有同樣的title，所以無法解析。
方法：
在外面這層用javascript解析，然后重命名，繼續往下用JSON控件解析...

JAVASCRIPT代碼：

var data = JSON.parse(trade);
var alipay_id = data.alipay_id;
var buyer_alipay_no = data.buyer_alipay_no;
var seller_nick = data.seller_nick;
var orders1 = data.orders;
var title1 = data.title;
var logistics_company1 = data.title;

這樣只能解決2個同名的JSON結構，當JSON存在3個同名的，1個在外層，2個嵌套在不同的對象里面，還是會報錯。

既然是path問題，那就看看是否可以修改path。

官網上又這樣的路徑，依樣畫葫蘆,OK！

XPath	JSONPath	Description
/	$	the root object/element
.	@	the current object/element
/	. or []	child operator
..	n/a	parent operator
//	..	recursive descent. JSONPath borrows this syntax from E4X.
*	*	wildcard. All objects/elements regardless their names.
@	n/a	attribute access. JSON structures don't have attributes.
[]	[]	subscript operator. XPath uses it to iterate over element collections and for predicates. In Javascript and JSON it is the native array operator.
|	[,]	Union operator in XPath results in a combination of node sets. JSONPath allows alternate names or array indices as a set.
n/a	[start:end:step]	array slice operator borrowed from ES4.
[]	?()	applies a filter (script) expression.
n/a	()	script expression, using the underlying script engine.
()	n/a	grouping in Xpath

 

 

XPath	JSONPath	Result
/store/book/author	$.store.book[*].author	the authors of all books in the store
//author	$..author	all authors
/store/*	$.store.*	all things in store, which are some books and a red bicycle.
/store//price	$.store..price	the price of everything in the store.
//book[3]	$..book[2]	the third book
//book[last()]	$..book[(@.length-1)] $..book[-1:]	the last book in order.
//book[position()<3]	$..book[0,1] $..book[:2]	the first two books
//book[isbn]	$..book[?(@.isbn)]	filter all books with isbn number
//book[price<10]	$..book[?(@.price<10)]	filter all books cheapier than 10
//*	$..*	all Elements in XML document. All members of JSON structure.

官網關於path的URL：http://wiki.pentaho.com/display/EAI/JSON+Input

根據官網提示鏈接到： http://goessner.net/articles/JsonPath/ 

（2）

2015/07/15 15:30:48 - trade_detail.0 - ERROR (version 5.4.0.1-130, build 1 from 2015-06-14_12-34-55 by buildguy) : Unexpected Error : org.pentaho.di.core.exception.KettleException:
2015/07/15 15:30:48 - trade_detail.0 - org.pentaho.di.core.exception.KettleException:
2015/07/15 15:22:48 - trade_detail.0 -
2015/07/15 15:22:48 - trade_detail.0 -
2015/07/15 15:22:48 - trade_detail.0 -We can not find and data with path [$..logistics_company]
原因:JSON中存在不完整的字段，無法解析。
方法：
1、用javascript腳本讀取內容
2、勾選json控件-->內容-->設置忽視不完整的路徑

  （不過這個方式對嵌套多層的無效）

javascript腳本例子：

 

var json={"status":1,"info":"u83b7u53d6u6210u529f","data":[{ "name":"dingding","information":"電視迷","Region_id":"3","type":"1"},{"id":"5","name":"kenwong","information":"you are ok","Region_id":"5","type":"100"}]}
var data=json.data;

var str1 ="";
var str2 ="";
var str3 =""; 
for(i=0;i<data.length;i++)
{
str1 += data[i].name +","
str2 += data[i].information +",";
str3 += data[i].id +",";
 }