This project bridges the gap between the flexibility of OData queries and the powerful search capabilities of Elasticsearch, allowing you to leverage OData query syntax to query your Elasticsearch indices. Whether you're dealing with complex nested objects, arrays, or just need to perform simple searches, this extension has got you covered.

To start using this extension, include it in your project and configure it to point to your Elasticsearch instance. Here's a quick example:

PM> Install-Package Nest.OData

TargetFramework: net8.0

Dependencies:
Microsoft.AspNetCore.OData (>= 8.2.5)
NEST (>= 7.17.5)

[HttpGet]
public async Task<IActionResult> Get(ODataQueryOptions<Document> queryOptions)
{
    var searchDescriptor = queryOptions.ToElasticQuery<Document>();

    var response = await _elasticClient.SearchAsync<Document>(searchDescriptor);

    if (response.IsValid)
    {
        return Ok(response.Documents);
    }
    else
    {
        return BadRequest();
    }
}

Replace Document with your document class that maps to your Elasticsearch index.

This extension supports a wide range of OData query functionalities, tailored specifically for Elasticsearch's query DSL. Here's what you can do:

• Filtering ($filter): Translate OData filters into Elasticsearch query DSL, supporting logical operators, comparison operations, and some basic functions.
• Ordering ($orderby): Support for sorting by multiple fields, including support for nested objects.
• Pagination ($skip and $top): Implement pagination through Elasticsearch's from and size parameters.
• Aggregation ($apply): Support for translating aggregation transformations, including groupby and aggregate functions like sum, max, min, average, and countdistinct.
• Selection ($select): Ability to specify which fields to include in the response, reducing the payload size and focusing on the relevant data.
• Expansion ($expand): Support for applying additional $filter and $select conditions on complex nested objects.

• Equals (eq)
• Not Equals (ne)
• Greater Than (gt)
• Greater Than or Equal (ge)
• Less Than (lt)
• Less Than or Equal (le)
• And
• Or
• In

• startswith
• endswith
• contains
• substringof

• any
• all

Enums are treated as strings, allowing for straightforward comparisons without additional conversion steps. Collections, including simple arrays and nested objects, can be queried using the any and all functions, providing a seamless experience for working with complex data structures.

The extension provides support for nested queries, allowing you to delve into nested objects and arrays within your documents to perform fine-grained searches. Whether you're filtering on properties of nested objects or querying arrays for specific elements, this extension translates your OData queries into efficient Elasticsearch DSL queries.

$filter=Tags/any(t: t/Name eq 'bug')

{
    "query": {
        "nested": {
            "path": "Tags",
            "query": {
              "term": {
                  "Name": {
                    "value": "bug"
                  }
              }
          }
      }
  }
}

$filter=Category in ('Electronics', 'Books')

{
  "query": {
    "terms": {
      "Category": ["Electronics", "Books"]
    }
  }
}

$filter=Id eq 42 and ((Color eq 'Red') or (Color eq 'Green') or (Color eq 'Blue'))

{
  "query": {
    "bool": {
      "must": [
        {
          "term": {
            "Id": {
              "value": 42
            }
          }
        },
        {
          "bool": {
            "minimum_should_match": 1,
            "should": [
              {
                "term": {
                  "Color": {
                    "value": "Red"
                  }
                }
              },
              {
                "term": {
                  "Color": {
                    "value": "Green"
                  }
                }
              },
              {
                "term": {
                  "Color": {
                    "value": "Blue"
                  }
                }
              }
            ]
          }
        }
      ]
    }
  }
}

Contributions are welcome! Whether you're fixing a bug, adding a new feature, or improving the documentation, please feel free to make a pull request.

This project is licensed under the MIT License.

If you encounter any issues or have questions, please file an issue on this repository.