NEST API Default value for GeoShapes fields

问题

We are using a filter as per following:

filters.Add(fq => fq
    .Term(t => t
        .Field(f => f.LocalityId)
        .Value(locationParams[2])) || fq
    .GeoShape(g => g
        .Field("locationShape")
        .Relation(GeoShapeRelation.Within)
        .IndexedShape(f => f
            .Id(searchCriteria.spLocationId)
            .Index(indexName)
            .Path("geometry")
        )
    )
);

However, if the geometry field is missing, Elasticsearch throws an exception.

Is there anyway to avoid this by using a default (Null Value) in the mapping or any other way.

回答1:

It is not possible to avoid the exception in this case. Elasticsearch assumes that the parameters that the user provides to a pre-indexed shape are valid.

Ideally, the values supplied to the indexed shape should be constrained in a manner that prevents an end user from supplying invalid values. If that is unfeasible, you could run a bool query with filter clauses of exists query and ids query on the indexName index before adding the indexed shape geoshape query filter to the search request.

For example

private static void Main()
{
    var documentsIndex = "documents";
    var shapesIndex = "shapes";
    var host = "localhost";
    var pool = new SingleNodeConnectionPool(new Uri($"http://{host}:9200"));

    var settings = new ConnectionSettings(pool)
        .DefaultMappingFor<Document>(m => m.IndexName(documentsIndex))
        .DefaultMappingFor<Shape>(m => m.IndexName(shapesIndex));

    var client = new ElasticClient(settings);

    if (client.Indices.Exists(documentsIndex).Exists)
        client.Indices.Delete(documentsIndex);

    client.Indices.Create(documentsIndex, c => c
        .Map<Document>(m => m
            .AutoMap()
        )
    );

    if (client.Indices.Exists(shapesIndex).Exists)
        client.Indices.Delete(shapesIndex);

    client.Indices.Create(shapesIndex, c => c
        .Map<Shape>(m => m
            .AutoMap()
        )
    );

    client.Bulk(b => b
        .IndexMany(new [] { 
            new Document 
            {
                Id = 1,
                LocalityId = 1,
                LocationShape = GeoWKTReader.Read("POLYGON ((30 20, 20 15, 20 25, 30 20))")
            },
            new Document
            {
                Id = 2,
                LocalityId = 2
            },
        })
        .IndexMany(new [] 
        {
            new Shape 
            {
                Id = 1,
                Geometry = GeoWKTReader.Read("POLYGON ((20 35, 10 30, 10 10, 30 5, 45 20, 20 35))")
            }
        })
        .Refresh(Refresh.WaitFor)
    );

    var shapeId = 1;

    var searchResponse = client.Search<Shape>(s => s
        .Size(0)
        .Query(q => +q
            .Ids(i => i.Values(shapeId)) && +q
            .Exists(e => e.Field("geometry"))
        )
    );

    Func<QueryContainerDescriptor<Document>, QueryContainer> geoShapeQuery = q => q;

    if (searchResponse.Total == 1)
        geoShapeQuery = q => +q
            .GeoShape(g => g
                .Field("locationShape")
                .Relation(GeoShapeRelation.Within)
                .IndexedShape(f => f
                    .Id(shapeId)
                    .Index(shapesIndex)
                    .Path("geometry")
                )
            );

    client.Search<Document>(s => s
        .Query(q => +q
            .Term(t => t
                .Field(f => f.LocalityId)
                .Value(2)
            ) || geoShapeQuery(q)
        )
    );
}

public class Document
{
    public int Id { get; set; }
    public int LocalityId { get; set; }
    public IGeoShape LocationShape { get; set; }
}

public class Shape
{
    public int Id { get; set; }
    public IGeoShape Geometry { get; set; }
}

If var shapeId = 1; is changed to var shapeId = 2; then the geoshape query is not added to the filter clauses when searching on the documents index.

来源：https://stackoverflow.com/questions/61913118/nest-api-default-value-for-geoshapes-fields