Add unaccent extension (npgsql#1501)

Closes npgsql#1530

EFCore.PG.sln

@@ -144,4 +144,4 @@ Global
 	GlobalSection(MonoDevelopProperties) = preSolution
 		StartupItem = Npgsql.csproj
 	EndGlobalSection
-EndGlobal
+EndGlobal

src/EFCore.PG/Extensions/NpgsqlFullTextSearchDbFunctionsExtensions.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using JetBrains.Annotations;
 using Microsoft.EntityFrameworkCore.Diagnostics;
 using NpgsqlTypes;
@@ -131,5 +131,34 @@ public static NpgsqlTsQuery WebSearchToTsQuery(
             [NotNull] string config,
             [NotNull] string query)
             => throw new InvalidOperationException(CoreStrings.FunctionOnClient(nameof(WebSearchToTsQuery)));
+
+        /// <summary>
+        /// Returns a new string that removes diacritics from characters in the given <paramref name="text" />.
+        /// </summary>
+        /// <param name="_">The <see cref="DbFunctions"/> instance.</param>
+        /// <param name="regDictionary">A specific text search dictionary.</param>
+        /// <param name="text">The text to remove the diacritics.</param>
+        /// <remarks>
+        /// <para>The method call is translated to <c>unaccent(regdictionary, text)</c>.</para>
+        /// 
+        /// See https://www.postgresql.org/docs/current/unaccent.html.
+        /// </remarks>
+        /// <returns>A string without diacritics.</returns>
+        public static string Unaccent([CanBeNull] this DbFunctions _, [NotNull] string regDictionary, [CanBeNull] string text)
+            => throw new InvalidOperationException(CoreStrings.FunctionOnClient(nameof(Unaccent)));
+
+        /// <summary>
+        /// Returns a new string that removes diacritics from characters in the given <paramref name="text" />.
+        /// </summary>
+        /// <param name="_">The <see cref="DbFunctions"/> instance.</param>
+        /// <param name="text">The text to remove the diacritics.</param>
+        /// <remarks>
+        /// <para>The method call is translated to <c>unaccent(text)</c>.</para>
+        ///
+        /// See https://www.postgresql.org/docs/current/unaccent.html.
+        /// </remarks>
+        /// <returns>A string without diacritics.</returns>
+        public static string Unaccent([CanBeNull] this DbFunctions _, [CanBeNull] string text)
+            => throw new InvalidOperationException(CoreStrings.FunctionOnClient(nameof(Unaccent)));
     }
 }

src/EFCore.PG/Query/ExpressionTranslators/Internal/NpgsqlFullTextSearchMethodTranslator.cs

@@ -31,6 +31,7 @@ public class NpgsqlFullTextSearchMethodTranslator : IMethodCallTranslator
         readonly RelationalTypeMapping _tsQueryMapping;
         readonly RelationalTypeMapping _tsVectorMapping;
         readonly RelationalTypeMapping _regconfigMapping;
+        readonly RelationalTypeMapping _regdictionaryMapping;
 
         public NpgsqlFullTextSearchMethodTranslator(
             [NotNull] IRelationalTypeMappingSource typeMappingSource,
@@ -42,6 +43,7 @@ public NpgsqlFullTextSearchMethodTranslator(
             _tsQueryMapping = typeMappingSource.FindMapping("tsquery");
             _tsVectorMapping = typeMappingSource.FindMapping("tsvector");
             _regconfigMapping = typeMappingSource.FindMapping("regconfig");
+            _regdictionaryMapping = typeMappingSource.FindMapping("regdictionary");
         }
 
         /// <inheritdoc />
@@ -64,6 +66,7 @@ public virtual SqlExpression Translate(
                     nameof(NpgsqlFullTextSearchDbFunctionsExtensions.PhraseToTsQuery)    when arguments.Count == 3 => ConfigAccepting("phraseto_tsquery"),
                     nameof(NpgsqlFullTextSearchDbFunctionsExtensions.ToTsQuery)          when arguments.Count == 3 => ConfigAccepting("to_tsquery"),
                     nameof(NpgsqlFullTextSearchDbFunctionsExtensions.WebSearchToTsQuery) when arguments.Count == 3 => ConfigAccepting("websearch_to_tsquery"),
+                    nameof(NpgsqlFullTextSearchDbFunctionsExtensions.Unaccent)           when arguments.Count == 3 => DictionaryAccepting("unaccent"),
 
                     // Methods not accepting a configuration
                     nameof(NpgsqlFullTextSearchDbFunctionsExtensions.ArrayToTsVector)    => NonConfigAccepting("array_to_tsvector"),
@@ -72,6 +75,7 @@ public virtual SqlExpression Translate(
                     nameof(NpgsqlFullTextSearchDbFunctionsExtensions.PhraseToTsQuery)    => NonConfigAccepting("phraseto_tsquery"),
                     nameof(NpgsqlFullTextSearchDbFunctionsExtensions.ToTsQuery)          => NonConfigAccepting("to_tsquery"),
                     nameof(NpgsqlFullTextSearchDbFunctionsExtensions.WebSearchToTsQuery) => NonConfigAccepting("websearch_to_tsquery"),
+                    nameof(NpgsqlFullTextSearchDbFunctionsExtensions.Unaccent)           => NonConfigAccepting("unaccent"),
 
                     _ => null
                 };
@@ -296,6 +300,22 @@ arguments[1] is SqlConstantExpression constant
                     method.ReturnType,
                     _typeMappingSource.FindMapping(method.ReturnType));
 
+            SqlExpression DictionaryAccepting(string functionName)
+                => _sqlExpressionFactory.Function(functionName, new[]
+                    {
+                        // For the regdictionary parameter, if a constant string was provided, just pass it as a string - regdictionary-accepting functions
+                        // will implicitly cast to regdictionary. For (string!) parameters, we add an explicit cast, since regdictionary actually is an OID
+                        // behind the scenes, and for parameter binary transfer no type coercion occurs.
+                        arguments[1] is SqlConstantExpression constant
+                            ? _sqlExpressionFactory.ApplyDefaultTypeMapping(constant)
+                            : _sqlExpressionFactory.Convert(arguments[1], typeof(string), _regdictionaryMapping),
+                        arguments[2]
+                    },
+                    nullable: true,
+                    argumentsPropagateNullability: TrueArrays[arguments.Count],
+                    method.ReturnType,
+                    _typeMappingSource.FindMapping(method.ReturnType));
+
             SqlExpression NonConfigAccepting(string functionName)
                 => _sqlExpressionFactory.Function(
                     functionName,

src/EFCore.PG/Storage/Internal/Mapping/NpgsqlRegconfigTypeMapping.cs

@@ -1,4 +1,4 @@
-using JetBrains.Annotations;
+using JetBrains.Annotations;
 using Microsoft.EntityFrameworkCore.Storage;
 using Npgsql.EntityFrameworkCore.PostgreSQL.Utilities;
 using NpgsqlTypes;

src/EFCore.PG/Storage/Internal/Mapping/NpgsqlRegdictionaryTypeMapping.cs

@@ -0,0 +1,24 @@
+using JetBrains.Annotations;
+using Microsoft.EntityFrameworkCore.Storage;
+using Npgsql.EntityFrameworkCore.PostgreSQL.Utilities;
+using NpgsqlTypes;
+
+namespace Npgsql.EntityFrameworkCore.PostgreSQL.Storage.Internal.Mapping
+{
+    public class NpgsqlRegdictionaryTypeMapping : NpgsqlTypeMapping
+    {
+        public NpgsqlRegdictionaryTypeMapping() : base("regdictionary", typeof(uint), NpgsqlDbType.Oid) { }
+
+        protected NpgsqlRegdictionaryTypeMapping(RelationalTypeMappingParameters parameters)
+            : base(parameters, NpgsqlDbType.Oid) { }
+
+        protected override RelationalTypeMapping Clone(RelationalTypeMappingParameters parameters)
+            => new NpgsqlRegdictionaryTypeMapping(parameters);
+
+        protected override string GenerateNonNullSqlLiteral(object value)
+            => $"'{EscapeSqlLiteral((string)value)}'";
+
+        string EscapeSqlLiteral([NotNull] string literal)
+            => Check.NotNull(literal, nameof(literal)).Replace("'", "''");
+    }
+}

src/EFCore.PG/Storage/Internal/NpgsqlTypeMappingSource.cs

@@ -98,6 +98,9 @@ public class NpgsqlTypeMappingSource : RelationalTypeMappingSource
         readonly NpgsqlRegconfigTypeMapping _regconfig             = new NpgsqlRegconfigTypeMapping();
         readonly NpgsqlTsRankingNormalizationTypeMapping _rankingNormalization = new NpgsqlTsRankingNormalizationTypeMapping();
 
+        // Unaccent mapping
+        readonly NpgsqlRegdictionaryTypeMapping _regdictionary = new NpgsqlRegdictionaryTypeMapping();
+
         // Built-in ranges
         readonly NpgsqlRangeTypeMapping        _int4range;
         readonly NpgsqlRangeTypeMapping        _int8range;
@@ -212,7 +215,9 @@ public NpgsqlTypeMappingSource([NotNull] TypeMappingSourceDependencies dependenc
 
                 { "tsquery",                     new[] { _tsquery                      } },
                 { "tsvector",                    new[] { _tsvector                     } },
-                { "regconfig",                   new[] { _regconfig                    } }
+                { "regconfig",                   new[] { _regconfig                    } },
+
+                { "regdictionary",               new[] { _regdictionary                } }
             };
 
             var clrTypeMappings = new Dictionary<Type, RelationalTypeMapping>

test/EFCore.PG.FunctionalTests/Northwind.sql

@@ -6,6 +6,7 @@ SET client_min_messages = warning;
 GO
 
 CREATE EXTENSION "uuid-ossp";
+CREATE EXTENSION "unaccent";
 
 CREATE TABLE "Employees" (
 	"EmployeeID" SERIAL,

test/EFCore.PG.FunctionalTests/Query/FullTextSearchDbFunctionsNpgsqlTest.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Linq;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.EntityFrameworkCore.TestModels.Northwind;
@@ -859,6 +859,49 @@ public void Complex_query()
             Assert.Equal("<b>Accounting</b> <b>Manager</b>", headline);
         }
 
+        [Fact]
+        public void Unaccent()
+        {
+            using var context = CreateContext();
+            var _ = context.Customers
+                .Select(x => EF.Functions.Unaccent(x.ContactName))
+                .FirstOrDefault();
+
+            AssertSql(@"SELECT unaccent(c.""ContactName"")
+FROM ""Customers"" AS c
+LIMIT 1");
+        }
+
+        [Fact]
+        public void Unaccent_with_constant_regdictionary()
+        {
+            using var context = CreateContext();
+            var _ = context.Customers
+                .Select(x => EF.Functions.Unaccent("unaccent", x.ContactName))
+                .FirstOrDefault();
+
+            AssertSql(@"SELECT unaccent('unaccent', c.""ContactName"")
+FROM ""Customers"" AS c
+LIMIT 1");
+        }
+
+        [Fact]
+        public void Unaccent_with_parameter_regdictionary()
+        {
+            using var context = CreateContext();
+            var regDictionary = "unaccent";
+            var _ = context.Customers
+                .Select(x => EF.Functions.Unaccent(regDictionary, x.ContactName))
+                .FirstOrDefault();
+
+            AssertSql(
+                @"@__regDictionary_1='unaccent'
+
+SELECT unaccent(@__regDictionary_1::regdictionary, c.""ContactName"")
+FROM ""Customers"" AS c
+LIMIT 1");
+        }
+
         void AssertSql(params string[] expected)
             => Fixture.TestSqlLoggerFactory.AssertBaseline(expected);
 

test/EFCore.PG.FunctionalTests/TestModels/Northwind/NorthwindNpgsqlContext.cs

@@ -12,6 +12,7 @@ protected override void OnModelCreating(ModelBuilder modelBuilder)
             base.OnModelCreating(modelBuilder);
 
             modelBuilder.HasPostgresExtension("uuid-ossp");
+            modelBuilder.HasPostgresExtension("unaccent");
 
             modelBuilder.Entity<CustomerQuery>().ToSqlQuery(@"SELECT ""c"".""CustomerID"", ""c"".""Address"", ""c"".""City"", ""c"".""CompanyName"", ""c"".""ContactName"", ""c"".""ContactTitle"", ""c"".""Country"", ""c"".""Fax"", ""c"".""Phone"", ""c"".""PostalCode"", ""c"".""Region"" FROM ""Customers"" AS ""c""");
         }