[英]Java - Filtering an array of JSON objects by multiple properties
I have an object stored in Cloudant like this : 我有一个像这样存储在Cloudant中的对象:
{
"attr1": "value",
"Objects": [{
"code": "v1",
"allowNull": "true",
"country": "BE"
},
{
"code": "v2",
"allowNull": "false",
"country": "EG"
}
]
}
And I want to do a filter criteria by code/country, so the output would be only one object of Objects list. 而且我想按代码/国家/地区做一个过滤条件,因此输出将只是“对象”列表的一个对象。
Is there a way to do that from Cloudant side? 有办法从Cloudant方面做到这一点吗? Or an efficient way to be done at Java side ?
还是在Java方面可以完成的有效方法?
You can achieve this with a map-reduce view in Cloudant. 您可以使用Cloudant中的map-reduce视图来实现。 Try something along the lines of this:
尝试一些类似的方法:
function(doc) {
if (doc && doc.Objects) {
doc.Objects.forEach(function(obj) {
emit([obj.code, obj.country], obj);
});
}
}
This emits all items in the Objects
list into the index, with a vector-valued key [code, country]
. 这会使用向量值键
[code, country]
将“ Objects
列表中的所有项目发出到索引中。
curl -s -XPOST -H "content-type:application/json" 'https://skruger.cloudant.com/demo/_design/query/_view/by_code_country?reduce=false' -d '{ "keys": [["v1","BE"]] }'
{"total_rows":2,"offset":0,"rows":[
{"id":"1c593a931bcd7f0052ed8f9184810fd9","key":["v1","BE"],"value":
{"code":"v1","allowNull":"true","country":"BE"}}
]}
You can query by code only, using the {}
wildcard marker, eg 您只能使用
{}
通配符标记按代码查询,例如
curl -g 'https://skruger.cloudant.com/demo/_design/query/_view/by_code_country?reduce=false&startkey=["v1"]&endkey=["v1",{}]'
{"total_rows":2,"offset":0,"rows":[
{"id":"1c593a931bcd7f0052ed8f9184810fd9","key":["v1","BE"],"value":
{"code":"v1","allowNull":"true","country":"BE"}}
]}
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