solr-net-linq

SolrNet IQueryable provider. Extend SolrNet functionality by adding LINQ to SOLR support for basic methods. Compatible with OData.

Code Sample

Prerequisites

To use LINQ with SolrNet you need to have ISolrOperations<TEntity> or even ISolrBasicReadOnlyOperations<TEntity>. By default TEntity should be a type with properties marked with SolrField attribute, however it is not mandatory if you going to set another mapping manager when initializing a query. For instance

public class Product
{
    [SolrUniqueKey("id")]
    public string Id { get; set; }

    [SolrField("cat")]
    public ICollection<string> Categories { get; set; }

    [SolrField("popularity")]
    public decimal? Popularity { get; set; }
}

IQueryable initialization

Once you have solr operations interface, call AsQueryable() extension method to create IQueryable<T>. For instance

var solr = ServiceLocator.Current.GetInstance<ISolrOperations<Product>>();
IQueryable<Product> solrLinq = solr.AsQueryable()

Now you can use supported linq methods.

Getting results

To get result you can

• Call ToSolrQueryResultsAsync() or ToSolrQueryResults() extensions methods to get normal SolrNet query result

SolrQueryResults<Product> result = solrLinq.Where(p => p.Popularity.HasValue).Take(10).ToSolrQueryResults();

• Trigger result by starting enumeration like any other IQueryable result triggering

Product[] result = solrLinq.Where(p => p.Popularity.HasValue).Take(10).ToArray();

Customization and workarounds for not suppported capabilities

It is possible to combine linq and regular SolrNet QueryOptions and main query. For instance if you need to append facets:

IQueryable<Product> solrLinq = solr.AsQueryable(setup =>
{
    // Set q parameter. By default *:* will be used.
    // LINQ Where method append fq (Filter Query) to query options and not affect main query
    options.MainQuery = new SolrQuery("some query");

    // Configure SolrNet QueryOptions.
    // This function will be called after applying query options from LINQ
    // You can setup options not covered by LINQ, for instance facets
    options.SetupQueryOptions = queryOptions =>
    {
        queryOptions.AddFacets();
    };

    // override default serializer if needed
    options.SolrFieldSerializer = new DefaultFieldSerializer();

    // override default mapping manager if needed
    options.MappingManager = new AttributesMappingManager();
});

Supported methods

OrderBy, OrderByDescending, ThenBy, ThenByDescending

• Order by field

Product[] result = solrLinq.OrderBy(p => p.Price).ThenBy(p => p.Id).ToArray();

• Order by functions (not all of SOLR functions currently supported)

Product[] result = solrLinq.OrderBy(p => Math.Pow(p.Price,3) + 1).ToArray();

Where

• Simple comparison

// result fq  
// price:{12 TO *}
Product[] result = solrLinq.Where(p => p.Price > 12).ToArray();

• Not equal

// result fq  
// (*:* NOT id:(qwe))
Product[] result = solrLinq.Where(p => p.Id != "qwe").ToArray();

• Conditional expressions

// result fq  
// (popularity:{7 TO *} OR ((*:* NOT popularity:[* TO *]) AND price:{7 TO *}))
Product[] result = solrLinq.Where(p => (p.Popularity != null ? p.Popularity.Value : p.Price) > 7).ToArray();

• Contains() method

// result fq  
// (price:((1) OR (2) OR (3)))
List<decimal> list = new List<decimal> {1, 2, 3};
Product[] result = solrLinq.Where(p => list.Contains(p.Price)).ToArray();

• Any() method

// result fq  
// cat:(qwe)
Product[] result = solrLinq.Where(p => p.Categories.Any(s => s == "qwe")).ToArray();

Select

• Anonymous and regular types with fields, pseudo field, functions and transformers

var result = solrLinq.Select(p => 
    new {
            p.Id, 
            p.Categories, 
            Qwe = Math.Pow(2,2), // evaluated locally
            Next = new Product2 {Id = p.Id} // evaluated locally after selecting required info from solr
            ValStr = SolrExpr.Transformers.Value("qwe"), // value transformer evaluated in solr
            Score= SolrExpr.Fields.Score() // score pseudo field evaluated in solr
        }).OrderBy(arg => arg.Score) // allowed to use expressions evaluated in solr for ordering
  	  .ToSolrQueryResults();

• Combine Select with other methods

var result = solrLinq
  .Where(p => p.Id != null)
  .Select(p => new {p.Id, p.Price, p.Categories, Score= SolrExpr.Fields.Score()})
  .Where(arg => arg.Categories.Any(s => s == "electronics"))
  .OrderBy(arg => arg.Id).ThenBy(arg=>arg.Score) 
  .Select(arg => new {arg.Id})
  .FirstOrDefault(arg2 => arg2.Id != null);

Paging

• Top
• Skip

Any

• Any
• AnyAsync

Count

• Count
• CountAsync
• LongCount
• LongCountAsync

First

• First
• FirstAsync
• FirstOrDefault
• FirstOrDefaultAsync

Single

• Single
• SingleAsync
• SingleOrDefault
• SingleOrDefaultAsync

Cast

Cast to interface and get SolrQueryResults object of interface type

SolrQueryResults<IProduct> result = solrLinq
  .Where(p => p.Id != null)
  .Cast<IProduct>
  .ToSolrQueryResults();

Nuget

https://www.nuget.org/packages/SolrNet.Linq

Contribution

Please feel free to create issues and pool requests to develop branch