我的目标是将elasticsearch结果转换为rxjs流，并考虑使用scroll API在每次调用时获取1个数据点。但是，我的rxjs流似乎没有返回第二个弹性查询（searchElastic）的结果。
以下是我的代码示例：
import * as Rx from 'rxjs';
import {elasticClient} from '../Helpers.ts';
function searchElastic({query, sort}) {
const body: any = {
size: 1,
query,
_source: { excludes: ['logbookType', 'editable', 'availabilityTag'] },
sort
};
// keep the search results "scrollable" for 30 secs
const scroll = '30s';
return Rx.Observable
.fromPromise(elasticClient.search({ index: 'data', body, scroll }))
.concatMap(({_scroll_id, hits: {hits}}) => {
const subject = new Rx.Subject();
if(hits.length) {
// initial data
subject.onNext(hits[0]._source as ElasticDoc);
console.log(hits[0]._id);
const handleDoc = (err, res) => {
if(err) {
subject.onError(err);
return;
}
const {_scroll_id, hits: {hits}} = res;
if(!hits.length) {
subject.onCompleted();
} else {
subject.onNext(hits[0]._source as ElasticDoc);
console.log(hits[0]._id);
setImmediate(() =>
elasticClient.scroll({scroll, scrollId: _scroll_id},
handleDoc));
}
};
setImmediate(() =>
elasticClient.scroll({scroll, scrollId: _scroll_id},
handleDoc));
} else {
subject.onCompleted();
}
return subject.asObservable();
});
}
function getEntries() {
const entriesQuery = {
query: {
filtered: {
filter: {
bool: {
must: [{
range: {
creationTimestamp: {
gte: "2018-04-01T07:55:59.915Z",
lte: "2018-04-01T07:57:08.915Z"
}
}
}, {
query: {
query_string: {
query: "+type:*scan*"
}
}
}]
}
}
}
},
sort: [{
creationTimestamp: {
order: "asc"
},
id: {
order: "asc"
}
}]
};
return searchElastic(entriesQuery)
.concatMap(entry => {
// all entries are logged correctly
console.log(entry.id);
// array that contains MongoDB _ids as strings
const ancestors = entry.ancestors || [];
// if no parents => doesn't match
if(!ancestors.length) {
return Rx.Observable.empty();
}
const parentsQuery = {
query: {
filtered: {
filter: {
bool: {
must: [{
range: {
creationTimestamp: {
gte: "2018-04-01T07:55:59.915Z",
lte: "2018-04-01T07:57:08.915Z"
}
}
}, {
query: {
query_string: {
query: "+type:*block* +name:*Report*"
}
}
}]
}
}
}
},
sort: [{
creationTimestamp: {
order: "asc"
},
id: {
order: "asc"
}
}]
};
parentsQuery.query.filtered.filter.bool.must.push({
terms: {
id: ancestors
}
});
// fetch parent entries
return searchElastic(parentsQuery)
.count()
.concatMap(count => {
// count is always 0 even though entries are logged
// in the searchElastic console.logs
console.log(entry.id, count);
return Rx.Observable.just(entry);
});
});
}
function executeQuery() {
try {
getEntries()
.subscribe(
(x) => console.log(x.id),
err => console.error(err),
() => {}
)
} catch(e) {
console.error(e);
}
}
看起来它是rxjs问题，因为所有祖先条目都会被记录，但count始终返回0.
P.S。使用elasticsearch v1.7
答案 0 :(得分：0)
在玩了几个rxjs个主题的例子之后，在观察者订阅它之前，似乎主题正在完成（onCompleted）。
工作示例
var subject = new Rx.Subject();
var subscription = subject.subscribe(
function(x) {
console.log('onNext: ' + x);
},
function(e) {
console.log('onError: ' + e.message);
},
function() {
console.log('onCompleted');
});
subject.onNext(1);
// => onNext: 1
subject.onNext(2);
// => onNext: 2
subject.onCompleted();
// => onCompleted<!DOCTYPE html>
<html>
<head>
<script src="//code.jquery.com/jquery-2.1.0.min.js"></script>
<title>JS Bin</title>
<script src="//cdn.jsdelivr.net/rsvp/3.0.6/rsvp.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/rxjs/2.2.28/rx.all.min.js"></script>
</head>
</html>
破碎的例子
var subject = new Rx.Subject();
subject.onNext(1);
// => onNext: 1
subject.onNext(2);
// => onNext: 2
subject.onCompleted();
// => onCompleted
var subscription = subject.subscribe(
function(x) {
console.log('onNext: ' + x);
},
function(e) {
console.log('onError: ' + e.message);
},
function() {
console.log('onCompleted');
});<!DOCTYPE html>
<html>
<head>
<script src="//code.jquery.com/jquery-2.1.0.min.js"></script>
<title>JS Bin</title>
<script src="//cdn.jsdelivr.net/rsvp/3.0.6/rsvp.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/rxjs/2.2.28/rx.all.min.js"></script>
</head>
</html>
所以我通过将searchElastic更改为以下内容来修复它：
function searchElasticStream({query, sort}) {
const body: any = {
size: 1,
query,
_source: { excludes: ['logbookType', 'editable', 'availabilityTag'] },
sort
};
// keep the search results "scrollable" for 30 secs
const scroll = '30s';
return Rx.Observable
.fromPromise(elasticClient.search({ index: 'data', body, scroll }))
.flatMap(({_scroll_id, hits: {hits}}) => {
const subject = new Rx.Subject();
// this made the difference
setImmediate(() => {
if(hits.length) {
// initial data
subject.onNext(hits[0]._source as ElasticDoc);
const handleDoc = (err, res) => {
if(err) {
subject.onError(err);
return;
}
const {_scroll_id, hits: {hits}} = res;
if(!hits.length) {
subject.onCompleted();
} else {
subject.onNext(hits[0]._source as ElasticDoc);
setImmediate(() =>
elasticClient.scroll({scroll, scrollId: _scroll_id},
handleDoc));
}
};
setImmediate(() =>
elasticClient.scroll({scroll, scrollId: _scroll_id},
handleDoc));
} else {
subject.onCompleted();
}
});
return subject.asObservable();
});
}