# Elasticsearch NEST query on a list of attachments **URL:** \ **Category:** Elasticsearch\ **Created:** [November 6, 2018, 8:46pm UTC](https://discuss.elastic.co/t/elasticsearch-nest-query-on-a-list-of-attachments/155619 "2018-11-06T20:46:03Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![alina.frey](https://avatars.discourse-cdn.com/v4/letter/a/c57346/32.png) [@alina.frey](https://discuss.elastic.co/u/alina.frey)\ **Post date:** [November 6, 2018, 8:46pm UTC](https://discuss.elastic.co/t/elasticsearch-nest-query-on-a-list-of-attachments/155619/1 "2018-11-06T20:46:03Z")
- Using ingest-attachment plugin. - Elasticsearch version: 5.5.1 - NEST: 5.5 - My goal is to be able to search the Content of a list of documents called PersonDocuments attached to IndexablePersonModel, and return the persons that have documents that contain the query term. - PersonDocuments is a list of IndexablePersonDocument on the IndexablePersonModel ```auto public IEnumerable PersonDocuments { get; set; } ``` - And one of the attributes of IndexablePersonDocument is string Content. - How do I query on the PersonDocuments? - Here is the query that I have so far: ```auto QueryContainer Query(QueryContainerDescriptor < IndexablePersonModel > q) { var returnQuery = q .Match(m => m .Field(a => a.PersonDocuments.FirstOrDefault().Content) .Boost(SearchConstants.Boosts.XXXLarge) .Query(Form.Query)) || q.FunctionScore(fs => fs .MaxBoost(SearchConstants.Boosts.Large) .Functions(ff => ff .FieldValueFactor(fvf => fvf .Field(p => p...) .Factor(0.0001))) .Query(query => query .MultiMatch(m => m .Fields(f => f...) .Operator(Operator.And) .Query(Form.Query)))); return returnQuery; } ``` - The line with the problem is: ```auto .Field(a => a.PersonDocuments.FirstOrDefault().Content) ``` - I don't know how to loop through the list PersonDocuments. - The following is the index that I created on persons: ```auto { "person-index": { "mappings": { "person": { "properties": { "name": { "type": "text", "fields": { "keyword": { "type": "text", "analyzer": "person-name-keyword" }, "raw": { "type": "keyword" } }, "analyzer": "person-name-analyzer" }, "personDocuments": { "type": "nested", "properties": { "attachment": { "properties": { "author": { "type": "text", "fields": { "keyword": { "type": "keyword", "ignore_above": 256 } } }, "content": { "type": "text", "fields": { "keyword": { "type": "keyword", "ignore_above": 256 } } }, "content_length": { "type": "long" }, "content_type": { "type": "text", "fields": { "keyword": { "type": "keyword", "ignore_above": 256 } } }, "date": { "type": "date" }, "detect_language": { "type": "boolean" }, "indexed_chars": { "type": "long" }, "keywords": { "type": "text", "fields": { "keyword": { "type": "keyword", "ignore_above": 256 } } }, "language": { "type": "text", "fields": { "keyword": { "type": "keyword", "ignore_above": 256 } } }, "name": { "type": "text", "fields": { "keyword": { "type": "keyword", "ignore_above": 256 } } }, "title": { "type": "text", "fields": { "keyword": { "type": "keyword", "ignore_above": 256 } } } } }, "content": { "type": "text", "fields": { "keyword": { "type": "keyword", "ignore_above": 256 } } }, "id": { "type": "integer" }, "name": { "type": "text", "analyzer": "document-path-analyzer" }, "path": { "type": "text", "fields": { "keyword": { "type": "keyword", "ignore_above": 256 } } } } } } } }, "settings": { ... } } } ``` ---
**Author:** ![forloop](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/forloop/32/9021_2.png) [@forloop](https://discuss.elastic.co/u/forloop)\ **Post date:** [November 7, 2018, 10:05am UTC](https://discuss.elastic.co/t/elasticsearch-nest-query-on-a-list-of-attachments/155619/2 "2018-11-07T10:05:54Z")
> [@alina.frey](#): > > - The line with the problem is: > > ```auto > .Field(a => a.PersonDocuments.FirstOrDefault().Content) > > ``` > > - I don't know how to loop through the list PersonDocuments. The lambda expression here is used to construct the path to the correct field, in a strongly typed fashion; the resulting serialized output for that expression would be ```json "field": "personDocuments.content" ``` Where the indexed field is a collection of values, such as in the case of ```auto public IEnumerable PersonDocuments { get; set; } ``` The query will be executed across the values in the collection for each document. You'll notice that the mapping for `personDocuments` includes the properties of only a single `personDocument`. This is because Elasticsearch has no concept of an ["array" datatype](https://www.elastic.co/guide/en/elasticsearch/reference/current/array.html). As far as it is concerned, you can index a single `personDocument`, multiple `personDocument` instances, or none into the `personDocuments` field. What will be mapped back to your POCO however will be the original JSON that you indexed. Your POCO models the `personDocuments` field as a collection, so your model/application always expects a collection (including null or empty) back from Elasticsearch. A couple of points though 1. `personDocuments` is mapped as a [`nested` data type](https://www.elastic.co/guide/en/elasticsearch/reference/current/nested.html), so a query on a field of `personDocuments` needs to be a `nested` query i.e. you need to put the `Match` query on the `Content` field inside of [a `Nested` query](https://www.elastic.co/guide/en/elasticsearch/client/net-api/current/nested-query-usage.html) 2. A collection of the top level `person` documents will be returned, and not `personDocuments`. If you wish to get the matching `personDocuments`, take a look at [`Inner hits`](https://www.elastic.co/guide/en/elasticsearch/reference/current/search-request-inner-hits.html). ---
**Author:** ![alina.frey](https://avatars.discourse-cdn.com/v4/letter/a/c57346/32.png) [@alina.frey](https://discuss.elastic.co/u/alina.frey)\ **Post date:** [November 7, 2018, 5:01pm UTC](https://discuss.elastic.co/t/elasticsearch-nest-query-on-a-list-of-attachments/155619/3 "2018-11-07T17:01:31Z")
- I modified the query to the following, and still getting zero hits. Please advise. ```auto QueryContainer Query(QueryContainerDescriptor < IndexablePersonModel > q) { var returnQuery = q .FunctionScore(fs => fs...) .Nested(n => n .Boost(SearchConstants.Boosts.XXXLarge) .InnerHits(i => i.Explain()) .Path(p => p.PersonDocuments) .Query(nq => +nq .Bool(b => b .Should( s => s.Term(p => p.PersonDocuments.First().Attachment.Content.Suffix(SearchConstants.Keyword), ) ).MinimumShouldMatch(MinimumShouldMatch.Fixed(1)) ) ) .IgnoreUnmapped() ); return returnQuery; } ``` - When I do a search from Postman with "query-term": ```auto POST: http://localhost:9200/index-name/_search BODY: { "query": { "query_string": { "query": "query-term" } } } ``` - I get the following output: ```auto { "took": 61, "timed_out": false, "_shards": { "total": 2, "successful": 2, "failed": 0 }, "hits": { "total": 4, "max_score": 1, "hits": [ { "_index": "", "_type": "person", "_id": "72802", "_score": 1, "_source": { "attribute1": { "input": [ ... ], "weight": 0 }, "attribute2": false, ... "personDocuments": [ { "attachment": { "content_type": "text/plain; charset=ISO-8859-1", "language": "en", "content": "", "content_length": 7 }, "name": ".pdf", "id": 0, "content": "" } ] } }, ... ... ... ] } } ``` - So, I know I am retrieving the objects in Postman, but I don't know how to match that in C# NEST code. ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [December 5, 2018, 5:01pm UTC](https://discuss.elastic.co/t/elasticsearch-nest-query-on-a-list-of-attachments/155619/4 "2018-12-05T17:01:50Z")
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