Elasticsearch - Highlight not working on attachments

Question

I have indexed some attachments into my Elasticsearch database. When I make a full text search with words in the attachment, I get the result back(hits), but I do not get "highlight" in the response.

I am not able to figure out what I am doing wrong, here is my code:

    [ElasticsearchType(Name = "temporaryapplication")]
public class Attachment
{
    [String(Name = "_content", Store = true, TermVector = TermVectorOption.WithPositionsOffsets)]
    public string Content { get; set; }
    [String(Name = "_content_type")]
    public string ContentType { get; set; }
    [String(Name = "_name")]
    public string Name { get; set; }
}

}

public class Document
{
    [Attachment]
    public Attachment File { get; set; }
}

Here I am making a search request:

    public async Task<StructuredSearchResponse> GetApplications(Guid positionId, SearchQuery query)
    {
        var searchResult =
            await _client.LowLevel.SearchAsync<string>(ApplicationsIndexName, "temporaryapplication", new SearchRequest()
            {
                From = (query.PageSize*query.PageNumber) - query.PageSize,
                Size = query.PageSize,
                Query = GetQuery(query),
                Source = GetFields(),
                Aggregations = GetAggregations(),
                Highlight = new Highlight() {
                    Fields = new Dictionary<Field, IHighlightField>
                    {
                        { "file.content", new HighlightField
                            {
                                Type = HighlighterType.Postings,
                                HighlightQuery = new MatchQuery
                                {
                                    Field = "file.content",
                                    Query = query.Freetext
                                }
                            }
                        } 
                    }
                }
            });

        return searchResult.ToStructuredSearchResponse(query.PageSize, query.PageNumber);
    }

The index mapping:

                var indexDescriptor =
                new CreateIndexDescriptor(new IndexName {Name = ApplicationsIndexName}).Mappings(
                    ms => ms.Map<TemporaryApplication>(m => m.AutoMap())
                        .Map<Attachment>(m => m.AutoMap()));


            _client.CreateIndex(indexDescriptor);

The POCO for mapping:

public class TemporaryApplication
{
    [String(Name = "FirstName")]
    public string FirstName { get; set; }
    [String(Name = "LastName")]
    public string LastName { get; set; }
    [String(Name = "Education")]
    public string Education { get; set; }
    [String(Name = "WorkExperience")]
    public string WorkExperience { get; set; }
    [String(Name = "Age")]
    public string Age { get; set; }
    [String(Name = "Id")]
    public int Id { get; set; }
    [Attachment]
    public Attachment File { get; set; }
}

Method for indexing attachment:

    public async void IndexDocument(Attachment attachmentDocument)
    {
        var doc = new Document()
        {
            File = attachmentDocument,
        };

        var updateResponse = _client.Update<TemporaryApplication, object>(5, descriptor => descriptor
        .Doc(new { file = doc.File }));
    }

JSON for document:

   {
   "_index": "applications",
   "_type": "temporaryapplication",
   "_id": "5",
   "_version": 2,
   "found": true,
     "_source": {
          "FirstName": "Petter",
          "LastName": "Stordalen",
          "Education": "master",
          "WorkExperience": "3years",
          "Age": "8.0",
          "Id": 5,
          "file": {
               "_name": "07443a5a-ad56-4610-bd53-8b8ea43a4c89 (1).doc",
                "_content_type": "application/msword",
                "_content":
                "e1xydGYxXGFuc2lcYW5zaWNwZzEyNTJcZGVmZjBcbm91aWNvbXBhdFxkZWZsYW5nMTA0NHtcZm9udHRibHtcZjBcZm5pbFxmY2hhcnNldDAgQ2FsaWJyaTt9fQ0Ke1wqXGdlbmVyYXRvciBSaWNoZWQyMCAxMC4wLjE0MzkzfVx2aWV3a2luZDRcdWMxIA0KXHBhcmRcc2EyMDBcc2wyNzZcc2xtdWx0MVxmMFxmczIyXGxhbmcyMCBWQ1hDVlhDVlhDVlhDVlhWWENWWENWXHBhcg0KfQ0KAA=="
        }
    }
   }

JSON for mapping: Elasticsearch mapping updated GetQuery Method:

public static class ElasticsearchExtensions
{
    public static StructuredSearchResponse ToStructuredSearchResponse(this ElasticsearchResponse<string> response, int pageSize, int pageNumber)
    {
        return new StructuredSearchResponse(JObject.Parse(response.Body), pageSize,pageNumber);
    }

    public static QueryContainer AddEducation(this QueryContainer queryContainer, SearchQuery query)
    {
        if (query.Education.Count > 0)
        {
            for (var i = 0; i < query.Education.Count; i++)
            {
                queryContainer |= new MatchQuery()
                {
                    Field = "Education",
                    Query = query.Education[i]
                };
            }
        }
        return queryContainer;
    }

    public static QueryContainer AddWorkExperience(this QueryContainer queryContainer, SearchQuery query)
    {
        if (query.WorkExperience.Count > 0)
        {
            if (queryContainer != null)
            {
                queryContainer &= new MatchQuery()
                {
                    Field = "WorkExperience",
                    Query = query.WorkExperience[0]
                };

                for (var i = 1; i < query.WorkExperience.Count; i++)
                {
                    queryContainer |= new MatchQuery()
                    {
                        Field = "WorkExperience",
                        Query = query.WorkExperience[i]
                    };
                }
            }
            else
            {
                for (var i = 0; i < query.WorkExperience.Count; i++)
                {
                    queryContainer |= new MatchQuery()
                    {
                        Field = "WorkExperience",
                        Query = query.WorkExperience[i]
                    };
                }
            }
        }
        return queryContainer;
    }

    public static QueryContainer AddAgeInterval(this QueryContainer queryContainer, SearchQuery query)
    {
        if (query.FromAge != "" || query.ToAge != "")
        {
            dynamic From = null;
            dynamic To = null;

            if (query.FromAge != null)
            {
                From = Convert.ToDouble(query.FromAge);
            }

            if (query.ToAge != null)
            {
                To = Convert.ToDouble(query.ToAge);
            }

            if (queryContainer == null)
            {
                queryContainer = new NumericRangeQuery()
                {
                    Field = "Age",
                    GreaterThanOrEqualTo = From,
                    LessThanOrEqualTo = To,
                };
            }
            else
            {
                queryContainer &= new NumericRangeQuery()
                {
                    Field = "Age",
                    GreaterThanOrEqualTo = From,
                    LessThanOrEqualTo = To
                };
            }
        }

        return queryContainer;
    }

    public static QueryContainer AddFreeTextSearch(this QueryContainer queryContainer, SearchQuery query)
    {
        if (!(string.IsNullOrEmpty(query.Freetext)))
        {
            if (queryContainer == null)
            {
                queryContainer |= new QueryStringQuery()
                {
                    Fields =
                        Field.Create("FirstName").And("LastName").And("Education").And("WorkExperience").And("Age").And("file.content"),
                    Query = "*" + query.Freetext + "*"
                };
            }
            else
            {
                queryContainer &= new QueryStringQuery() 
                {
                    Fields =
                        Field.Create("FirstName").And("LastName").And("Education").And("WorkExperience").And("Age").And("file.content"),
                    Query = "*" + query.Freetext + "*"
                };
            }
        }
        return queryContainer;
    }
}

}

This is what query parameter contains:

Query Parameter

Can someone see what I am doing wrong?

Answer 1

According to documentation your mapping is wrong

If you want to highlight your attachment content, you will need to set "store": true and "term_vector":"with_positions_offsets" for your attachment field. Here is a full script which does it:

I see that you have all of that in code, so maybe you have added it after index was created. Try to drop and recreate it

It seems that Nest is not able to map complex type

  var indexDescriptor =
                new CreateIndexDescriptor(new IndexName {Name = ApplicationsIndexName}).Mappings(
                    ms => ms.Map<TemporaryApplication>(m => m.AutoMap())
                        .Map<Attachment>(m => m.AutoMap()
                        .Properties(ps => ps
      .Attachment(s => s.Name(p => p.File)
        .FileField(ff => ff.Name(p => p.File).TermVector(TermVectorOption.WithPositionsOffsets))
      )
    )));