How to pass in a list FunctionScoreFunctions

[GaryTurpin]

Currently, I only have 2 functions but I will be adding approximately 8 more in the near future and I want the code to look clean for the next person that comes along. I know I can set it up like the following:

.Functions (
      freshness => freshnessEnabled ? freshness.Gauss(l => l.creationDate, d => d.Decay(.9).Offset("7d").Orgin(orginFreshness).Scale("3d") : null,
      distance => distanceEnabled ? distance.Gauss(l => l.location, d => d.Decay(.9).Offset("10mi").Orgin(orginDistance).Scale("10mi") : null
)

I want to know if there is a way to do this by passing a list/array into Functions so that I can make my method look clean after I have 10 functions. Plus I will have a lot of conditional logic that will turn the individual functions on and off:

private List<FunctionScoreFunction> GetFunctions(){
      var list = new List<FunctionScoreFunction>();
      if (freshnessEnabled)
           list.Add(new GaussFunction<Document>(l => l.creationDate, d => d.Decay(.9).Offset("7d").Orgin(orginFreshness).Scale("3d");
      if (distanceEnabled)
           list.Add(new GaussFunction<Document>(l => l.creationDate, d => d.Decay(.9).Offset("10mi").Orgin(orginDistance).Scale("10mi");

      return list;
}

public Results Search (){
      ....
      var functions = GetFunctions();
      .Functions( functions)
      ....
}

[RossLieberman]

I ended up doing this by using a List<> of Func<> and adding the items like you

var scoringAlgorithm = new List<Func<FunctionScoreFunctionsDescriptor<T>, FunctionScoreFunction<T>>>();

//example 1:
scoringAlgorithm.Add(functions => functions
                    .Gauss(fieldName.FieldName, d => d
                                    .Offset(string.Format("{0}d", fieldName.Offset))
                                    .Scale(string.Format("{0}d", fieldName.Scale))
                                    .Decay((double?)fieldName.Decay))
                                    .Weight((float)fieldName.Boost)
                        );

Then when I want to add it to my query

var searchBuilder = new SearchDescriptor<T>();

searchBuilder.Query = (q => q.FunctionScore(fs => fs
                                    .Functions(scoringAlgorithm.ToArray())
                                .Query(fsq => searchParameters.QueryContainer)
                                .BoostMode(FunctionBoostMode.Sum)
                                .ScoreMode(FunctionScoreMode.Sum)
                    ));

However if list was null or empty, it looked like NEST wouldn't send in the Query without it, so I added this right before the search:

//In order for ES.NET to properly search using FunctionScore. It needs to pass in an empty array if there aren't any function calculations
if (scoringAlgorithm == null || !scoringAlgorithm.Any())
    scoringAlgorithm =  new List<Func<FunctionScoreFunctionsDescriptor<T>, FunctionScoreFunction<T>>>();

It ends up sending an empty Functions [] array but I didn't find any impact into Elastic Search

[GaryTurpin]

Thanks! Ill give that a try.

[GaryTurpin]

It works perfectly. Thanks again @RossLieberman

[gmarz]

@GaryTurpin while the solution proposed by @RossLieberman works, it shouldn't be necessary- the descriptor should expose an IEnumerable<IFunctionScoreFunction> version of Functions() so that you can pass your list in directly.

I just added this in the above commit. So in the next release you'll be able to do:

var functions = GetFuctions(); // returns a List<FunctionScoreFunction<T>>
.Functions(functions);

as you were originally looking for.

Thanks for opening this issue, and @RossLieberman thank you for replying with a work around.

[GaryTurpin]

@gmarz Ill be looking for that in the next release. Thanks.