Cannot convert lambda expression to type 'PostData' because it is not a delegate type

Elastic Stack Elasticsearch
1

I have this code in my .net core app

var searchResponse = client.Search<Person>(s => s
.From(0)
.Size(10)
.Query(q => q
     .Match(m => m
        .Field(f => f.FirstName)
        .Query("Martijn")
     )
)

);

which I got from this page https://www.elastic.co/guide/en/elasticsearch/client/net-api/current/nest-getting-started.html

I'm getting an error at design time "Cannot convert lambda expression to type 'PostData' because it is not a delegate type". I have referenced Elasticsearch and System.Linq.

What am I missing?

2

I've also tried this syntax from https://www.elastic.co/guide/en/elasticsearch/client/net-api/1.x/nest-quick-start.html

QueryContainer query = new TermQuery

{
Field = "firstName",
Value = "martijn"
};

var searchRequest = new SearchRequest
{
From = 0,
Size = 10,
Query = query
};

And now I get an error "cannot convert from 'Nest.SearchRequest' to 'Elasticsearch.Net.PostData"

I'm not sure why it is so hard to make a simple API call here.

3

First thing to check, are the NEST and Elasticsearch.Net NuGet packages referenced both the same version number?

4

Yes, they are both Version 6.2.0.

I've managed to use the ElasticLowLevelClient successfully to Index, but if I use that to Count or Search since it seems to just do a post, I can't map the response object to actually use the data I'm trying to get.

5

Ok. What is the type of client above? Would you be able to provide a short, but complete, example of the issue?

Also, would you be able to provide more details of the environment

  • Windows, MacOS, Linux?
  • framework TFM e.g. netcoreapp2.0
6

Hi, so this is embarrassing. I was wanting to use the Low Level Client, but that was obviously not right. I then tried adding the Nest reference and changing to High Level Client but that didn't work either.
Then I closed VS Code, reopened it and all of a sudden it works. Frustrating!

For info, in case anyone else has this -
Running on Windows
Elasticsearch v6.3.0 running locally (just for dev purposes)
Developing in C# (dotnet core), using VSCode.

Code now looks like:

var node = new Uri(Config.Configuration["elasticsearch:0:uri"]);
var settings = new ConnectionSettings( node );
Client = new ElasticClient(settings);
QueryContainer query = new MatchQuery
{
	Field = keyValue.Key,
    Query = keyValue.Value.ToString()
};
var searchRequest = new SearchRequest(index.IndexName, index.IndexType)
	{
		Query = query
	};
var searchResults = Client.Search<object>(searchRequest);

Thanks again!

7

Glad you figured it out @StephM :+1:

8

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