Search document collections with GroupDocs.Search Leave feedback
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GroupDocs.Search is the one API in the suite that works on a collection rather than a single file. You build an index over a folder of documents once, then query it as often as you like — the index does the reading, so queries stay fast no matter how large the corpus grows.
That makes it a two-phase API: index, then search. The entry point is Index, not a “searcher”.
Warning
GroupDocs.Search.Indexclashes withSystem.Index, the type behind C# range syntax. In any file that hasusing System;— which is almost any file — a bareIndexfails to compile:error CS0104: 'Index' is an ambiguous reference between 'GroupDocs.Search.Index' and 'System.Index'The examples below open with
using Index = GroupDocs.Search.Index;, which resolves it for the whole file. Fully qualifying every use works too, but reads badly.
The index lives in a folder of its own, separate from the documents. Add reads a folder of documents into it; Search queries what has been indexed.
using System;
using System.IO;
using GroupDocs.Search;
using GroupDocs.Search.Results;
using Index = GroupDocs.Search.Index;
// The index is a folder the library owns; keep it out of your documents folder
string indexFolder = "search-build-index/index";
string documentsFolder = "archive";
Index index = new Index(indexFolder);
// Index every supported document in the folder
index.Add(documentsFolder);
SearchResult result = index.Search("throughput");
Console.WriteLine("Documents found: " + result.DocumentCount);
Console.WriteLine("Total occurrences: " + result.OccurrenceCount);
for (int i = 0; i < result.DocumentCount; i++)
{
FoundDocument document = result.GetFoundDocument(i);
// FilePath is absolute; the file name is the useful part here
Console.WriteLine(" " + Path.GetFileName(document.DocumentInfo.FilePath)
+ " (" + document.OccurrenceCount + " occurrences)");
}
This example indexes the archive folder — three working documents from the engagement: discovery-findings.docx, steering-minutes.docx and phase-two-proposal.pdf. Put them in a folder named archive next to your executable.
Documents found: 3
Total occurrences: 7
discovery-findings.docx (4 occurrences)
phase-two-proposal.pdf (2 occurrences)
steering-minutes.docx (1 occurrences)
Exact matching fails on scanned documents and typos. Fuzzy search accepts a similarity level — how many character edits away a word may be and still count as a hit.
using System;
using GroupDocs.Search;
using GroupDocs.Search.Options;
using GroupDocs.Search.Results;
using Index = GroupDocs.Search.Index;
string indexFolder = "search-fuzzy/index";
string documentsFolder = "archive";
Index index = new Index(indexFolder);
index.Add(documentsFolder);
SearchOptions options = new SearchOptions();
options.FuzzySearch.Enabled = true;
options.FuzzySearch.FuzzyAlgorithm = new TableDiscreteFunction(3);
// Matches "throughput" even when spelled "througput" or "throughtput"
SearchResult result = index.Search("throughput", options);
Console.WriteLine("Documents found: " + result.DocumentCount);
Console.WriteLine("Total occurrences: " + result.OccurrenceCount);
This example indexes the archive folder — three working documents from the engagement: discovery-findings.docx, steering-minutes.docx and phase-two-proposal.pdf. Put them in a folder named archive next to your executable.
Documents found: 3
Total occurrences: 7
Query text supports AND, OR and NOT, so you can express the same conditions a user would type into a search box. All three archived documents mention throughput; only the phase-two proposal mentions a forecast, so this query returns the other two.
using System;
using System.IO;
using GroupDocs.Search;
using GroupDocs.Search.Results;
using Index = GroupDocs.Search.Index;
string indexFolder = "search-boolean/index";
string documentsFolder = "archive";
Index index = new Index(indexFolder);
index.Add(documentsFolder);
SearchResult result = index.Search("throughput AND NOT forecast");
Console.WriteLine("Documents found: " + result.DocumentCount);
for (int i = 0; i < result.DocumentCount; i++)
{
FoundDocument document = result.GetFoundDocument(i);
Console.WriteLine(" " + Path.GetFileName(document.DocumentInfo.FilePath));
}
This example indexes the archive folder — three working documents from the engagement: discovery-findings.docx, steering-minutes.docx and phase-two-proposal.pdf. Put them in a folder named archive next to your executable.
Documents found: 2
discovery-findings.docx
steering-minutes.docx
NoteAn index is durable. PointIndexat an existing index folder and it reopens what is already there rather than rebuilding — callAddagain only when documents change, andUpdateto refresh ones that were modified.
GroupDocs.Search also offers phrase, wildcard, regex, faceted and date-range queries, highlights matches in the source document, indexes asynchronously with progress events, runs OCR over scanned pages, supports synonyms, homophones and stop words, and can distribute an index across a search network.
- GroupDocs.Search for .NET documentation — the full product guide
- Supported file formats
- API reference
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