LinqToSolr

LinqToSolr is an intuitive and lightweight C# library designed to enhance Solr queries with the power of Linq. It seamlessly integrates Solr search capabilities into .NET applications, facilitating cleaner and more maintainable code. LinqToSolr is suitable for developing complex search solutions or simplifying query logic.

nuget package:

To install:

dotnet add package LinqToSolr

Supported Methods

The library supports a variety of Linq methods, including but not limited to:

• Where
• First
• FirstOrDefault
• Select
• Contains
• Array.Contains(solrField)
• StartsWith
• EndsWith
• GroupBy
• Take
• Skip
• OrderBy
• ThenBy
• OrderByDescending
• ThenByDescending
• ToListAsync
• AddOrUpdateAsync
• DeleteAsync

Usage Instructions

Defining a Model

First, define a model class to represent your Solr document:

public class MyProduct{
  public int Id{get;set;}

  [LinqToSolrField("username")]
  public string Name{get;set}
  public string Group{get;set}

  [LinqToSolrField("deleted")]
  public bool IsDeleted{get;set}
  public string[] Tags{get;set;}

  [LinqToSolrFieldIgnore]
  public string CustomField{}
}

Configuration

Initialize a configuration class for the service:

var solrConfig = new LinqToSolrConfiguration("http://localhost:8983/") // URL to Solr instance, if solr has different location (not under/solr) set it to  http://localhost:8983/somecustomlocation
                .MapCoreFor<MyProduct>("MyProductIndex"); // Mapping your model to Solr Index

Creating a Service

Instantiate the base service and provide the configuration:

var solrService = new LinqToSolrService(solrConfig);

Extending LinqToSolrService

You may create a custom service that inherits from LinqToSolrService:

public class MyProductService: LinqToSolrService{

  private  Task<IQueryable<>> IQueryable<MyProduct> IsNotDeleted()
  {
       return  AsQueryable<MyProduct>().Where(x=> !x.IsDeleted);
  }

  public async Task<ICollection<MyProduct>> GetProductsByIds(params int[] ids)
  {
      return await IsNotDeleted().Where(x=> ids.Contains(x.Id)).ToListAsync();
  }
}

Linq Query Examples

Where Clause

await solrService.AsQueryable<MyProduct>().Where(x => x.Group == "MyGroup1").ToListAsync();

FirstOrDefault

var groupArray = new[] { "MyGroup1", "MyGroup2", "MyGroup3", "MyGroup4" };
var product = await solrService.AsQueryable<MyProduct>().FirstOrDefault(x => x.Id == 123);

OrderBy & OrderByDescending

var orderedProducts = await solrService.AsQueryable<MyProduct>()
                                        .Where(x => x.Group == "MyGroup1")
                                        .OrderBy(x => x.Id)
                                        .ThenByDescending(x => x.Name)
                                        .ToListAsync();

Contains Examples

solrService.AsQueriable<MyProduct>().Where(x=> x.Name.Contains("productName")).ToList();

var array = new[]{"str2", "str3", "str4"};
solrService.AsQueriable<MyProduct>().Where(x=> array.Contains(x.Name)).ToList();

solrService.AsQueriable<MyProduct>().Where(x=> x.Tags.Contains("tag1")).ToList();

OrderBy & OrderByDescending

await solrService.AsQueriable<MyProduct>().Where(x=> x.Group == "MyGroup1").OrderBy(x=>x.Id).ThenByDescending(x=>x.Name).ToListAsync();

Facets

            var docs = await solrService.AsQueriable<MyProduct>().ToFacetsAsync(x => x.IsActive) ;
            var activeList = docs[x=>x.IsActive]; // bool list of facets

            var docs = await solrService.AsQueriable<MyProduct>().Where(x=>x.IsActive).ToFacetsAsync(x => x.Tags) as LinqToSolrFacetDictionary<SolrDocument>; // facets with query for arrays
            var tagsList = docs.GetFacet<string[], string>(x => x.Tags);

Select Clause

solrService.AsQueriable<MyProduct>().Where(x=> x.Group == "MyGroup1").Select(x=x.Name).ToList();

solrService.AsQueriable<MyProduct>().Where(x=> x.Group == "MyGroup1").Select(x=x new {x.Name, x.Group}).ToList();

Solr Document Interaction

Adding or Updating Documents Add or update documents in a Solr core:

var products = new[] {
    new MyProduct { Id = 1, Name = "Product One" },
    new MyProduct { Id = 2, Name = "Product Two" },
    new MyProduct { Id = 3, Name = "Product Three" }
};

await solrService.AddOrUpdateAsync(products);

Deleting Documents Delete documents by specifying an array of ids:

await solrService.Where(x => x.Id == 123).DeleteAsync<MyProduct>();