c# - NEST 返回 null 而不是字段
问题描述
我使用弹性工作很长时间了,但我从未编写过获取一些数据的代码。而现在我遇到了麻烦。
我有一个索引,我想在其中检索投影在某个字段上的一些文档。我可以从字面上用 SQL 编写它
SELECT myDocumentField
FROM myIndex
但由于某种原因,我得到的是空值而不是值。
我的索引中有 6 个文档。所以我写了以下查询:
var elasticServiceNumbers = await _elasticClient.SearchAsync<ElasticRequest>(
s => s.Query(Selector));
它按预期工作并返回这 6 个值,除了它们的所有字段都是空的
好的,我也在尝试添加字段:
var elasticServiceNumbers = await _elasticClient.SearchAsync<ElasticRequest>(
s => s.StoredFields(sf => sf.Fields(f => f.ServiceNumber))
.Query(Selector));
var elasticServiceNumbers2 = await _elasticClient.SearchAsync<ElasticRequest>(
s => s.Source(sf => sf.Includes(fds => fds.Field(f => f.ServiceNumber)))
.Query(Selector));
但仍然不走运,并且字段保持其空值。
Kibana 显示该字段存在于索引中:
这里有什么问题?
Kibana 查询
{
"version": true,
"size": 500,
"sort": [
{
"_score": {
"order": "desc"
}
}
],
"_source": {
"excludes": []
},
"aggs": {
"2": {
"date_histogram": {
"field": "@timestamp",
"interval": "3h",
"time_zone": "Asia/Baghdad",
"min_doc_count": 1
}
}
},
"stored_fields": [
"*"
],
"script_fields": {},
"docvalue_fields": [
"@timestamp",
"fields.Date",
"fields.DeserializedMessage.Message.Date",
"fields.DeserializedMessage.Message.Periods.Begin",
"fields.DeserializedMessage.Message.Periods.End",
"fields.DeserializedMessage.Message.ResponseDate",
"fields.Periods.Begin",
"fields.Periods.End",
"fields.ResponseDate"
],
"query": {
"bool": {
"must": [
{
"match_all": {}
},
{
"range": {
"@timestamp": {
"gte": 1527973200000,
"lte": 1528577999999,
"format": "epoch_millis"
}
}
}
],
"filter": [],
"should": [],
"must_not": []
}
},
"highlight": {
"pre_tags": [
"@kibana-highlighted-field@"
],
"post_tags": [
"@/kibana-highlighted-field@"
],
"fields": {
"*": {}
},
"fragment_size": 2147483647
}
}
解决方案
看起来有问题的字段是doc value fields,因为它们是可搜索和可聚合的,但未存储_source
,即未存储发送到 Elasticsearch的原始文档。
使用 NEST 获取文档值字段
var searchResponse = client.Search<ElasticRequest>(s => s
.DocValueFields(f => f
.Field(ff => ff.ServiceNumber.Suffix("keyword"))
)
);
这是使用看起来是文档值字段的keyword
映射。serviceNumber