如何仅凭单个请求从CouchDB中获取某些文档的某些字段? [英] How to get from CouchDB only certain fields of certain documents with a single request?
问题描述
创建一个视图，该视图仅返回文档中值的子集，每个值的键和值都位于json字符串中.就像一个给定的视图按如下所示返回文档一样，是否可以为一个请求获取一些字段信息?谢谢你
{
"total_rows":10,
"offset":3,
"rows":[{
"id":"doc1",
"key":"abc123",
"value": {
"_id":"aaaa",
"_rev":"bbb",
"field1":"abc",
"field2":"bcd",
"field3":"cde",
"field4":"123",
"field5":"789",
"field6":"aa@email.com",
"field7":"ttt",
"field8":"iii",
"field9":[{
"field91":"tyui",
"field92":"55555"
}],
"field10"::"0000",
"field11"::"55555",
"field12"::"0030".........
}
}
我只想创建一个只返回以下内容的视图:
{
"field1":"abc",
"field2":"bcd",
"field3":"cde",
"field4":"123",
"field5":"789",
"field6":"aa@email.com",
"field7":"ttt",
"field8":"iii",
"field9":[{
"field91":"tyui",
"field92":"55555"
}]
}
create a view that return only a subset of values from a document, each with its key and value within a json string. like if one given view returns a document as this following, Is it possible to get some fields information for a one request? thank you
{
"total_rows":10,
"offset":3,
"rows":[{
"id":"doc1",
"key":"abc123",
"value": {
"_id":"aaaa",
"_rev":"bbb",
"field1":"abc",
"field2":"bcd",
"field3":"cde",
"field4":"123",
"field5":"789",
"field6":"aa@email.com",
"field7":"ttt",
"field8":"iii",
"field9":[{
"field91":"tyui",
"field92":"55555"
}],
"field10"::"0000",
"field11"::"55555",
"field12"::"0030".........
}
}
I just want to create a view that returns some fields only the following:
{
"field1":"abc",
"field2":"bcd",
"field3":"cde",
"field4":"123",
"field5":"789",
"field6":"aa@email.com",
"field7":"ttt",
"field8":"iii",
"field9":[{
"field91":"tyui",
"field92":"55555"
}]
}
推荐答案
一种地图函数，仅发出具有选定字段的新文档.例如，让我们仅映射field1(一个字符串)和field9(一个数组):
A map function that emits a new document with selected fields only. As an example, let's map field1 (a string) and field9 (an array) only:
function map(doc) {
emit(doc._id, {
field1: doc.field1,
field9: doc.field9
});
}
在上面的示例中，将使用键(原始文档ID)和值(您需要的映射字段)触发每个文档. 如果您打算以后添加reduce函数，这将很有用.
In the above example, each document will be fired with a key being the original doc ID and the value being the mapped fields you require. This is useful if you are planning to add a reduce function later.
根据您的用例，您可能只想发出映射的对象:
Depending on your use case, you may just want to emit the mapped objects:
function map(doc) {
emit({
field1: doc.field1,
field9: doc.field9
});
}
请参阅 http://guide.couchdb.org/draft/views.html 建立数据视图的文档非常好，您可以通过实验发现很多内容.
Please see http://guide.couchdb.org/draft/views.html The documentation on building data views is pretty good, you can discover a lot by experimenting..
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