Adding pattern-based search to your .NET app

Indx embeds directly into your .NET process. There is no separate search server to run, and nothing to configure before you start: pattern recognition and BM25 scoring handle typos and messy input without tokenizers, stemmers, or analyzers. This guide takes you from an empty project to your first filtered search.

Install

dotnet add package IndxSearchLib

Initialize and configure fields

Indx works on a JSON array of objects. Init parses the structure and discovers the fields with their types. Nothing is searchable by default. You assign each field a role yourself.

using Indx.Api;

var engine = new SearchEngine();

using var stream = File.OpenRead("products.json");
engine.Init(stream);

var name     = engine.GetField("name")!;
var category = engine.GetField("category")!;

name.Searchable = true;
name.Weight     = 2.0f;        // float, default 1.25, relative to other searchable fields

category.Filterable = true;
category.Facetable  = true;

A field can hold several roles at once. Here category is both filterable and facetable, so it can narrow results and show value counts in a sidebar.

Load and index

Stream the same JSON in again to load the documents, then build the index:

stream.Position = 0;
engine.Load(stream);
engine.Index();

The engine is now in the Ready state. From here you can also insert, update, and delete individual documents without rebuilding.

Search

var result = engine.Search(new Query("wireles", 20)); // typo is tolerated

foreach (var entry in result.Entries)
    Console.WriteLine($"key={entry.DocumentKey}  score={entry.Score}");

// Pull the full JSON for the matches:
var keys = result.Entries.Select(e => e.DocumentKey).ToArray();
var docs = engine.GetJsonDataOfKeys(keys);

Search returns keys and scores, not full documents. Fetch the JSON separately and keep the result list light.

A query like "wireles" still finds "Wireless Headphones". Pattern matching, no tuning required.

Filter results

Filters run server-side against the whole dataset. Never filter the returned array yourself: it only holds the top results, so you would miss matches.

var audio = engine.CreateValueFilter("category", "audio", out _);
var result = engine.Search(new Query("wireless", 20) { Filter = audio });

Range filters work the same way, and filters combine with &, |, and !:

var affordable = engine.CreateRangeFilter("price", 0, 50, out _);
var combined   = audio & affordable;

Next steps

• Getting started is the full walkthrough, including sorting and facets
• C# API reference
• Frontend in another stack? Self-host IndxCloudApi, a ready-to-deploy ASP.NET Core server, and call its REST API from anywhere