Nest Client在Elasticsearch中进行相等查询

Question

public class User 
{
    public string Email { get; set; }
}

client.Index(new User { Email ="test@test.te" });

Query in Linq C# for example :

rep.Where(user=>user.Email=="test@test.te");

That works correctly.

I use same query in Nest:

client.Search<Post>(q => q
.Query(qu => qu
.Term(te=>te.OnField("email").Value("test@test.te"))));

Document result count is zero!!

But :

client.Search<Post>(q => q
.Query(qu => qu
.Term(te=>te.OnField("email").Value("test"))));

Document result count is 1 - why?

How I can make equal-query in ElasticSearch?

Answer 1

It's all because analyzers. Your document is parsed to terms while indexing, which means that elasticsearch stores something like an array of strings ["test", "test", "te"] in row with your document. Depending on what anayzer is configured (I guess it's standard one), you may get different terms decomposition. On the other side, your term request is not analyzed; that's why first request returns nothing - there's no such string as "test@test.te" in index strings ["test", "test", "te"] , but there's a "test" string, so you get results for the second one. In your case you should use query_string query , but beware of the fact that such queries are analyzed too. It means, that if you index two documents, say {"Email":"test@test.te"} and {"Email":"test@gmail.com"} , without any flags query {"query":{"query_string":{"default_field":"Email","query":"test@test.te"}}} will return both documents because both of them contain "test" string in the index. To avoid this, use something like {"default_field":"Email","query":"test@test.te", "default_operator":"AND"}}} - default default operator is "OR" .

Speaking of NEST, use query like

client.Search<Post>(q => q
    .Query(qu => qu
    .QueryString(qs=>qs
        .OnField(x=>x.Email).Query("test@test.te").Operator(Operator.and)
        )
    )
);