[英]Compound query in Elasticsearch.NET
Imagine I have an index with a bunch of Order
objects in it想象一下,我有一个包含一堆
Order
对象的索引
class Order
{
int CustomerId { get; set; }
DateTime OrderDate { get; set; }
// Other fields
}
For a particular customer ID, I am able to find out the last order that the customer made with the following query:对于特定的客户 ID,我可以通过以下查询找到客户的最后一个订单:
IElasticClient client;
async Task<Order> GetLastOrder(int customerId)
{
var searchResponse = await client.SearchAsync<Order>(s => s
.Query(q => q
.Term(f => f
.Field(e => e.CustomerId)
.Term(customerId)) && q
.DateRange(r => r
.Field(e => e.OrderDate)
.LessThan(DateMath.Now)))
.Sort(o => o
.Descending(e => e.OrderDate))
.Size(1));
return searchResponse.ApiCall.Success
? searchResponse.Documents.First()
: null;
}
However, in order to support the data loader pattern, I want to query the last order made by multiple customers, given by a collection of customer IDs.但是,为了支持数据加载器模式,我想查询多个客户的最后一个订单,由一组客户 ID 给出。 I started off like this:
我是这样开始的:
async Task<IDictionary<int, Order>> GetLastOrders(IEnumerable<int> customerIds)
{
var searchResponse = await client.SearchAsync<Order>(s => s
.Query(q => q
.Terms(f => f
.Field(e => e.CustomerId)
.Terms(customerIds)) && q
.DateRange(r => r
.Field(e => e.OrderDate)
.LessThan(DateMath.Now)))
.Sort(o => o
.Descending(e => e.OrderDate))
.Size(1));
return searchResponse.ApiCall.Success
? searchResponse.Documents.ToDictionary(i => i.CustomerId)
: new Dictionary<string, Order>();
}
Unfortunately this does not work, as it only returns the first record of entire query, which will only return a single Order
.不幸的是,这不起作用,因为它只返回整个查询的第一条记录,它只会返回一个
Order
。 How can I modify this query to return one Order
per customer ID?如何修改此查询以针对每个客户 ID 返回一个
Order
?
Collapse can be used to return top most record for a field 折叠可用于返回字段的最高记录
await _client.SearchAsync<Order>(s => s
.Query(q => q
.Terms(f => f
.Field(e => e.CustomerId)
.Terms(cuIds)) && q
.DateRange(r => r
.Field(e => e.OrderDate)
.LessThan(DateMath.Now)))
.Sort(o => o
.Descending(e => e.OrderDate))
.Collapse(c => c.Field(e => e.CustomerId))
.Size(10)
);
corresponding query in DSL DSL 中的相应查询
{
"collapse": {
"field": "customerId"
},
"query": {
"bool": {
"must": [
{
"terms": {
"customerId": [
1,
2
]
}
},
{
"range": {
"orderDate": {
"lt": "now"
}
}
}
]
}
},
"size": 10,
"sort": [
{
"orderDate": {
"order": "desc"
}
}
]
}
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