Extend SearchResult and MemoryResult objects

[marcominerva]

We can easily provide a custom implementation of ISearchClient if we want to define our custom search logic. However, we are tied to use SearchResult and MemoryAnswer return type, so we cannot add custom information.

My suggestion is to add a property like "Metadata" to both SearchResult and MemoryAnswer:

/// <summary>
/// Allows to enrich the object with additional information
/// </summary>
[JsonPropertyName("metadata")]
[JsonPropertyOrder(30)]
[JsonExtensionData]
public Dictionary<string, object?>? Metadata { get; set; }

In this way, new implementations of SearchClient can use this property to customize the response.

[dluc]

How about extending the classes?

public class MySearchResult : SearchResult
{
    public Dictionary<string, object?>? Metadata { get; set; }
}

public class MySearchClient : ISearchClient
{
    public async Task<SearchResult> SearchAsync(...)
    {
        var result = new MySearchResult();
        
        // ....
        
        return result
    }
}

[marcominerva]

I tought about this, but I ended up with this proposal because I have noticed that the same Metadata approach is used also in Semantic Kernel and makes adding new properties straightforward, without the need to create new classes and the corresponding cast, and basically it has no impact on the default implementation.

[dluc]

yeah, I have mixed feelings about dictionaries, because they are not strongly typed and can lead to incompatible deployments. I agree about the ease of use, but they feel temporary and hacky, like strings, global state and static methods :-)

I've used them plenty, in KM too though, I try not to make things worse and refactor back to strongly typed code when I have a chance. In fact, that's something I should start looking at.

Logging and custom-non-indexed storage-payload are areas where I think they are useful, without too many problems, but I wouldn't use them to add new features.

Are there scenarios you're thinking of, where the current interface is too strict?

[marcominerva]

For example, I have some customers that would like to dynamically add information to the result, but only if their users have paid for it (let's say, the users have paid for a reranking feature, so the result should contain information about it).