Using binary type with NEST (elasticsearch)

Question

I want to have a binary parameter stored in my Elasticsearch server from my C# code. None of the types I tried to use in my index class translates to it.

Is there a way to explicitly instruct my program to store a binary, say from a byte array (could be converted to other types of course)?

Alternatively, is there a way to configure the parameter not to be stored (like with the Json property "stored": false)? As the main problem for me is the copying and indexing of that big parameter (not ideal but sufficient)

Update: I tried to downgrade my NEST version to 1.6.1 to use the attribute

[ElasticProperty(Name = "Data", Type = FieldType.Binary, Store = false)]
public byte[] Data { get; set; }

But when I save a document with that property, it still insists to map a string (I check by running GET mydb/_mapping in my Sense plugin)

Russ Cam · Accepted Answer · 2016-07-08 05:24:21Z

5

Elasticsearch supports binary types which can be set using attributes within NEST using the following in NEST 1.x

public class Document
{
    [ElasticProperty(Type = FieldType.Binary, Store = false)]
    public string Binary { get; set; }
}

or

public class Document
{
    [Binary(Store= false)]
    public string Binary { get; set; }
}

in NEST 2.x

Note that the binary type should be sent to Elasticsearch as a base 64 encoded string (1.x docs or 2.x docs). You could handle the conversion in your POCO type with something like (for 2.x)

public class Document
{
    [JsonIgnore]
    public byte[] BinaryBytes { get; set;}

    [Binary]
    [JsonProperty("binary")]
    public string Binary
    {
        get
        {
            return BinaryBytes != null ? Convert.ToBase64String(BinaryBytes) : null;
        }
        protected set
        {
            if (value != null) BinaryBytes = Convert.FromBase64String(value);
        }
    }
}  

client.CreateIndex("index-name", c => c
    .Mappings(m => m
        .Map<Document>(d => d
            .AutoMap()
        )
    )
);

which yields

{
  "mappings": {
    "document": {
      "properties": {
        "binary": {
          "type": "binary"
        }
      }
    }
  }
}

Then you would set BinaryBytes on the model, and NEST would send the contents of Binary in the request. You could also make Binary a private property if it would be less confusing for users of the model.

answered Jul 8, 2016 at 5:24

Russ Cam

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2 Comments

Oded Sayar Over a year ago

Thanks a bunch for your help, It seems that just adding the client.CreateIndex part instead of letting NEST doing it by itself gave me what I wanted

Russ Cam Over a year ago

@OdedSayar there are two things that Elasticsearch does to help in getting up and running; first, create an index automatically if it does not yet exist. This behaviour can be controlled with - elastic.co/guide/en/elasticsearch/reference/current/…. Secondly, dynamically map (i.e. infer the types of) the fields of a document if an explicit mapping is not specified for the document type. This can also be controlled - elastic.co/guide/en/elasticsearch/guide/current/…

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