Elasticsearch 6 NEST如何仅检索与搜索关键词完全匹配的文档？

Nice work getting the foundation right here—your use of the [Keyword] attribute on FullName is exactly what you need for exact match searches in Elasticsearch. Let's break down why this works, plus a few small tweaks to make your code more robust.

What You're Doing Correctly #

• The [Keyword] attribute tells Elasticsearch to index the FullName field as a single, unbroken string instead of splitting it into individual tokens. That means when you use a Term query, it's looking for the exact full value, not parts of the name.
• Your Term query is the perfect choice here—it's designed for matching exact values in keyword fields.

Small Improvements for Reliability #

• Guard Against Invalid Input: Add a check for null/empty FullName to avoid wasting a call to Elasticsearch.
• Validate the Response: Always check if the Elasticsearch response is valid before accessing documents—this helps catch issues like index errors or malformed queries.
• Cleaner Error Handling: Instead of just re-throwing the exception, consider logging it first to help debug issues later.

Updated Code #

Person SearchPerson(Person person) {
    // Guard clause for invalid input
    if (person == null || string.IsNullOrWhiteSpace(person.FullName)) {
        return null; // Or throw an ArgumentException if you want to enforce valid input
    }
    
    try {
        var response = client.Search<Person>(s => s
            .Query(q => q.Term(ff => ff.FullName, person.FullName)));
        
        // Check if the response is valid before proceeding
        if (!response.IsValid) {
            // Log response.ServerError.Details here if you have logging configured
            return null;
        }
        
        return response.Documents.FirstOrDefault();
    } catch (Exception ex) {
        // Log exception details (message, stack trace) here
        throw; // Re-throw to preserve the original stack trace
    }
}

public class Person {
    public Guid Id { get; set; }
    [Keyword]
    public string FullName { get; set; }
    public decimal Salary { get; set; } // Example of another property
}

Bonus: Case-Insensitive Exact Matches #

If you need exact matches that ignore case, you can add a lowercase normalizer to the [Keyword] attribute. First, define the normalizer in your index settings (you can do this when creating the index), then update the property:

[Keyword(Normalizer = "lowercase")]
public string FullName { get; set; }

Just make sure to convert the input person.FullName to lowercase before querying to match the normalized values in Elasticsearch.

内容的提问来源于stack exchange，提问作者Guid