基于netcore对ElasitSearch客户端NEST查询功能的简单封装NEST.Repository

NEST.Repository

A simple encapsulation with NEST client for search data form elasticsearch.

github

API

NESTReaderRepository

TEntity Get(TKey id);
TEntity Get(Func<QueryContainerDescriptor<TEntity>, QueryContainer> filterExp = null,
            Func<SourceFilterDescriptor<TEntity>, ISourceFilter> includeFieldExp = null,
            Expression<Func<TEntity, object>> sortExp = null, SortOrder sortType = SortOrder.Ascending);
Tuple<long, List<TEntity>> GetList(Func<QueryContainerDescriptor<TEntity>, QueryContainer> filterExp = null,
            Func<SourceFilterDescriptor<TEntity>, ISourceFilter> includeFieldExp = null,
            Expression<Func<TEntity, object>> sortExp = null, SortOrder sortType = SortOrder.Ascending
           , int limit = 10, int skip = 0)

NESTReaderRepositoryAsync

Task<TEntity> GetAsync(TKey id);
Task<TEntity> GetAsync(Func<QueryContainerDescriptor<TEntity>, QueryContainer> filterExp = null,
            Func<SourceFilterDescriptor<TEntity>, ISourceFilter> includeFieldExp = null,
            Expression<Func<TEntity, object>> sortExp = null, SortOrder sortType = SortOrder.Ascending);
Task<Tuple<long, List<TEntity>>> GetListAsync(Func<QueryContainerDescriptor<TEntity>, QueryContainer> filterExp = null,
            Func<SourceFilterDescriptor<TEntity>, ISourceFilter> includeFieldExp = null,
            Expression<Func<TEntity, object>> sortExp = null, SortOrder sortType = SortOrder.Ascending
           , int limit = 0, int skip = 0)

Depend on

NEST 6.0.2
Repository.IEntity 2.0.1 (or you can write IEntity<T> interface and you entity inherit it.)

How to Use

First, you need have an entity inherit IEntity<T>, T is type of PrimaryKey. eg

[Serializable]
[BsonIgnoreExtraElements]
public class User : IEntity<long>
{
    [BsonId]
    public long ID { get; set; }

    public double Age { get; set; }

    public double Sex { get; set; }

    public string Like { get; set; }
}

Second, you need have a repository inherit NESTReaderRepository or NESTReaderRepositoryAsync. eg

public class UserRepo : NESTReaderRepository<User, long>
{
    public static string connString = "http://localhost:9200/";

    public UserRepo()
        : base(connString)
    {

    }
}

Now, you can search data with simple api. eg

 static void Main(string[] args)
 {
    Repository.Container.RepositoryContainer.Register<UserRepo>();
    var userRepo = Repository.Container.RepositoryContainer.Resolve<UserRepo>();

    var user = userRepo.Get(9);
    var users = userRepo.GetList(
        filterExp: q => +q.Range(r => r.Field(f => f.Age).GreaterThan(13).LessThan(28)), 
        includeFieldExp: p => p.Includes(i => i.Fields(f => f.Age, f => f.Sex, f => f.Like)),
        sortExp: s => s.Age,
        sortType: Nest.SortOrder.Ascending,
        limit: 100,
        skip: 0
    );
 }

How to write a Query

0x00. Structured Search

By default, documents will be returned in _score descending order, where the _score for each hit is the relevancy score calculated for how well the document matched the query criteria.

q => q.DateRange(r => r
    .Field(f => f.{Field with DateTime Type})
    .GreaterThanOrEquals(new DateTime(2017, 01, 01))
    .LessThan(new DateTime(2018, 01, 01))
)

The benefit of executing a query in a filter context is that Elasticsearch is able to forgo calculating a relevancy score, as well as cache filters for faster subsequent performance.

 q => q.Bool(b => b.Filter(bf => bf
    .DateRange(r => r
        .Field(f => f.{Field with DateTime Type})
        .GreaterThanOrEquals(new DateTime(2017, 01, 01))
        .LessThan(new DateTime(2018, 01, 01))
        )
    )
)

0x01. Unstructured Search

Full text queries (find all documents that contain "Russ" in the lead developer first name field)

q => q.Match(m => m
    .Field(f => f.LeadDeveloper.FirstName)
    .Query("Russ")
)

0x02. Combining Search

q => q.Bool(b => b
    .Must(mu => mu
        .Match(m => m
            .Field(f => f.LeadDeveloper.FirstName)
            .Query("Russ")
        ), mu => mu
        .Match(m => m
            .Field(f => f.LeadDeveloper.LastName)
            .Query("Cam")
        )
    )
    .Filter(fi => fi
        .DateRange(r => r
            .Field(f => f.StartedOn)
            .GreaterThanOrEquals(new DateTime(2017, 01, 01))
            .LessThan(new DateTime(2018, 01, 01))
        )
    )
)

use operator

q => q.Match(m => m
        .Field(f => f.LeadDeveloper.FirstName)
        .Query("Russ")
    ) && q
    .Match(m => m
        .Field(f => f.LeadDeveloper.LastName)
        .Query("Cam")
    ) && +q
    .DateRange(r => r
        .Field(f => f.StartedOn)
        .GreaterThanOrEquals(new DateTime(2017, 01, 01))
        .LessThan(new DateTime(2018, 01, 01))
    )
)

Should ==> OR ==> ||
Must ==> And ==> &&
Must_Not ==> NOT==> !
Filter ==> +

the query will be converted to a bool query if use any operator, and the answer to the bool query is always yes or no , so that will not score.

Reference

https://www.elastic.co/guide/en/elasticsearch/client/net-api/current/writing-queries.html

https://www.elastic.co/guide/en/elasticsearch/client/net-api/current/bool-queries.html