// In C# because SQL's SUM returns NULL on an empty list, so we need the ?? operator, which doesn't exist in F#. At least not one that LINQ to Entities can parse
public static IOrderedQueryable <RevisionEntity> Search(
this IQueryable <RevisionEntity> revisions,
string searchTerm,
string plain,
string wildcard,
SearchOrder searchOrder
)
{
const NpgsqlTsRankingNormalization normalization =
NpgsqlTsRankingNormalization.DivideBy1PlusLogLength
| NpgsqlTsRankingNormalization.DivideByMeanHarmonicDistanceBetweenExtents;
IQueryable <RevisionEntity> where (IQueryable <RevisionEntity> query) =>
string.IsNullOrWhiteSpace(searchTerm)
? query
: query.Where(x => x.Tsv.Matches(Functions.WebSearchToTsQuery(plain).And(Functions.ToTsQuery(wildcard))));
IOrderedQueryable <RevisionEntity> order(IQueryable <RevisionEntity> query) =>
searchOrder == SearchOrder.Popularity
? query.OrderByDescending(x => x.Example.Users)
: query.OrderByDescending(x =>
x.Tsv.RankCoverDensity(Functions.WebSearchToTsQuery(plain).And(Functions.ToTsQuery(wildcard)), normalization));
return(revisions
.Apply(where)
.Apply(order));
}
/// <summary>
/// Calculates the rank of <paramref name="vector" /> for <paramref name="query" /> using the cover density
/// method while normalizing the result according to the behaviors specified by <paramref name="normalization" />
/// and using custom weighting for word instances depending on their labels (D, C, B or A).
/// http://www.postgresql.org/docs/current/static/textsearch-controls.html#TEXTSEARCH-RANKING
/// </summary>
public static float RankCoverDensity(
[NotNull] this NpgsqlTsVector vector,
[NotNull] float[] weights,
[NotNull] NpgsqlTsQuery query,
NpgsqlTsRankingNormalization normalization)
=> throw new InvalidOperationException(CoreStrings.FunctionOnClient(nameof(NpgsqlTsVector) + "." + nameof(RankCoverDensity)));
/// <summary>
/// Calculates the rank of <paramref name="vector" /> for <paramref name="query" /> using the cover density
/// method while normalizing the result according to the behaviors specified by <paramref name="normalization" />
/// and using custom weighting for word instances depending on their labels (D, C, B or A).
/// http://www.postgresql.org/docs/current/static/textsearch-controls.html#TEXTSEARCH-RANKING
/// </summary>
public static float RankCoverDensity(
this NpgsqlTsVector vector,
float[] weights,
NpgsqlTsQuery query,
NpgsqlTsRankingNormalization normalization) => throw new NotSupportedException();
/// <summary>
/// Calculates the rank of <paramref name="vector" /> for <paramref name="query" /> while normalizing
/// the result according to the behaviors specified by <paramref name="normalization" />
/// and using custom weighting for word instances depending on their labels (D, C, B or A).
/// http://www.postgresql.org/docs/current/static/textsearch-controls.html#TEXTSEARCH-RANKING
/// </summary>
public static float Rank(
this NpgsqlTsVector vector, float[] weights, NpgsqlTsQuery query, NpgsqlTsRankingNormalization normalization)
=> throw new InvalidOperationException(CoreStrings.FunctionOnClient(nameof(NpgsqlTsVector) + "." + nameof(Rank)));
/// <summary>
/// Calculates the rank of <paramref name="vector" /> for <paramref name="query" /> while normalizing
/// the result according to the behaviors specified by <paramref name="normalization" />.
/// http://www.postgresql.org/docs/current/static/textsearch-controls.html#TEXTSEARCH-RANKING
/// </summary>
public static float Rank(
this NpgsqlTsVector vector,
NpgsqlTsQuery query,
NpgsqlTsRankingNormalization normalization) => throw new NotSupportedException();
