Correct LTree type mapping logic

Fixes #2487

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

@@ -57,32 +57,32 @@ public class NpgsqlLTreeTranslator : IMethodCallTranslator, IMemberTranslator
                 nameof(LTree.IsAncestorOf)
                     => new PostgresBinaryExpression(
                         PostgresExpressionType.Contains,
-                        _sqlExpressionFactory.ApplyTypeMapping(instance!, _ltreeTypeMapping),
-                        _sqlExpressionFactory.ApplyTypeMapping(arguments[0], _ltreeTypeMapping),
+                        ApplyTypeMappingOrConvert(instance!, _ltreeTypeMapping),
+                        ApplyTypeMappingOrConvert(arguments[0], _ltreeTypeMapping),
                         typeof(bool),
                         _boolTypeMapping),
 
                 nameof(LTree.IsDescendantOf)
                     => new PostgresBinaryExpression(
                         PostgresExpressionType.ContainedBy,
-                        _sqlExpressionFactory.ApplyTypeMapping(instance!, _ltreeTypeMapping),
-                        _sqlExpressionFactory.ApplyTypeMapping(arguments[0], _ltreeTypeMapping),
+                        ApplyTypeMappingOrConvert(instance!, _ltreeTypeMapping),
+                        ApplyTypeMappingOrConvert(arguments[0], _ltreeTypeMapping),
                         typeof(bool),
                         _boolTypeMapping),
 
                 nameof(LTree.MatchesLQuery)
                     => new PostgresBinaryExpression(
                         PostgresExpressionType.LTreeMatches,
-                        _sqlExpressionFactory.ApplyTypeMapping(instance!, _ltreeTypeMapping),
-                        _sqlExpressionFactory.ApplyTypeMapping(arguments[0], _lqueryTypeMapping),
+                        ApplyTypeMappingOrConvert(instance!, _ltreeTypeMapping),
+                        ApplyTypeMappingOrConvert(arguments[0], _lqueryTypeMapping),
                         typeof(bool),
                         _boolTypeMapping),
 
                 nameof(LTree.MatchesLTxtQuery)
                     => new PostgresBinaryExpression(
                         PostgresExpressionType.LTreeMatches,
-                        _sqlExpressionFactory.ApplyTypeMapping(instance!, _ltreeTypeMapping),
-                        _sqlExpressionFactory.ApplyTypeMapping(arguments[0], _ltxtqueryTypeMapping),
+                        ApplyTypeMappingOrConvert(instance!, _ltreeTypeMapping),
+                        ApplyTypeMappingOrConvert(arguments[0], _ltxtqueryTypeMapping),
                         typeof(bool),
                         _boolTypeMapping),
 
@@ -171,7 +171,7 @@ public class NpgsqlLTreeTranslator : IMethodCallTranslator, IMemberTranslator
                 {
                     return new PostgresBinaryExpression(
                         PostgresExpressionType.LTreeMatchesAny,
-                        _sqlExpressionFactory.ApplyTypeMapping(Visit(predicateInstance), _ltreeTypeMapping),
+                        ApplyTypeMappingOrConvert(Visit(predicateInstance), _ltreeTypeMapping),
                         _sqlExpressionFactory.ApplyTypeMapping(Visit(array), _lqueryArrayTypeMapping),
                         typeof(bool),
                         _boolTypeMapping);
@@ -184,7 +184,7 @@ public class NpgsqlLTreeTranslator : IMethodCallTranslator, IMemberTranslator
                     return new PostgresBinaryExpression(
                         PostgresExpressionType.Contains,
                         _sqlExpressionFactory.ApplyTypeMapping(Visit(array), _ltreeArrayTypeMapping),
-                        _sqlExpressionFactory.ApplyTypeMapping(Visit(predicateArguments[0]), _ltreeTypeMapping),
+                        ApplyTypeMappingOrConvert(Visit(predicateArguments[0]), _ltreeTypeMapping),
                         typeof(bool),
                         _boolTypeMapping);
                 }
@@ -196,7 +196,7 @@ public class NpgsqlLTreeTranslator : IMethodCallTranslator, IMemberTranslator
                     return new PostgresBinaryExpression(
                         PostgresExpressionType.ContainedBy,
                         _sqlExpressionFactory.ApplyTypeMapping(Visit(array), _ltreeArrayTypeMapping),
-                        _sqlExpressionFactory.ApplyTypeMapping(Visit(predicateArguments[0]), _ltreeTypeMapping),
+                        ApplyTypeMappingOrConvert(Visit(predicateArguments[0]), _ltreeTypeMapping),
                         typeof(bool),
                         _boolTypeMapping);
                 }
@@ -208,7 +208,7 @@ public class NpgsqlLTreeTranslator : IMethodCallTranslator, IMemberTranslator
                     return new PostgresBinaryExpression(
                         PostgresExpressionType.LTreeMatches,
                         _sqlExpressionFactory.ApplyTypeMapping(Visit(array), _ltreeArrayTypeMapping),
-                        _sqlExpressionFactory.ApplyTypeMapping(Visit(predicateArguments[0]), _lqueryTypeMapping),
+                        ApplyTypeMappingOrConvert(Visit(predicateArguments[0]), _lqueryTypeMapping),
                         typeof(bool),
                         _boolTypeMapping);
                 }
@@ -220,7 +220,7 @@ public class NpgsqlLTreeTranslator : IMethodCallTranslator, IMemberTranslator
                     return new PostgresBinaryExpression(
                         PostgresExpressionType.LTreeMatches,
                         _sqlExpressionFactory.ApplyTypeMapping(Visit(array), _ltreeArrayTypeMapping),
-                        _sqlExpressionFactory.ApplyTypeMapping(Visit(predicateArguments[0]), _ltxtqueryTypeMapping),
+                        ApplyTypeMappingOrConvert(Visit(predicateArguments[0]), _ltxtqueryTypeMapping),
                         typeof(bool),
                         _boolTypeMapping);
                 }
@@ -267,7 +267,7 @@ public class NpgsqlLTreeTranslator : IMethodCallTranslator, IMemberTranslator
                     return new PostgresBinaryExpression(
                         PostgresExpressionType.LTreeFirstAncestor,
                         _sqlExpressionFactory.ApplyTypeMapping(Visit(array), _ltreeArrayTypeMapping),
-                        _sqlExpressionFactory.ApplyTypeMapping(Visit(predicateArguments[0]), _ltreeTypeMapping),
+                        ApplyTypeMappingOrConvert(Visit(predicateArguments[0]), _ltreeTypeMapping),
                         typeof(LTree),
                         _ltreeTypeMapping);
                 }
@@ -279,7 +279,7 @@ public class NpgsqlLTreeTranslator : IMethodCallTranslator, IMemberTranslator
                     return new PostgresBinaryExpression(
                         PostgresExpressionType.LTreeFirstDescendent,
                         _sqlExpressionFactory.ApplyTypeMapping(Visit(array), _ltreeArrayTypeMapping),
-                        _sqlExpressionFactory.ApplyTypeMapping(Visit(predicateArguments[0]), _ltreeTypeMapping),
+                        ApplyTypeMappingOrConvert(Visit(predicateArguments[0]), _ltreeTypeMapping),
                         typeof(LTree),
                         _ltreeTypeMapping);
                 }
@@ -291,7 +291,7 @@ public class NpgsqlLTreeTranslator : IMethodCallTranslator, IMemberTranslator
                     return new PostgresBinaryExpression(
                         PostgresExpressionType.LTreeFirstMatches,
                         _sqlExpressionFactory.ApplyTypeMapping(Visit(array), _ltreeArrayTypeMapping),
-                        _sqlExpressionFactory.ApplyTypeMapping(Visit(predicateArguments[0]), _lqueryTypeMapping),
+                        ApplyTypeMappingOrConvert(Visit(predicateArguments[0]), _lqueryTypeMapping),
                         typeof(LTree),
                         _ltreeTypeMapping);
                 }
@@ -303,7 +303,7 @@ public class NpgsqlLTreeTranslator : IMethodCallTranslator, IMemberTranslator
                     return new PostgresBinaryExpression(
                         PostgresExpressionType.LTreeFirstMatches,
                         _sqlExpressionFactory.ApplyTypeMapping(Visit(array), _ltreeArrayTypeMapping),
-                        _sqlExpressionFactory.ApplyTypeMapping(Visit(predicateArguments[0]), _ltxtqueryTypeMapping),
+                        ApplyTypeMappingOrConvert(Visit(predicateArguments[0]), _ltxtqueryTypeMapping),
                         typeof(string),
                         _ltreeTypeMapping);
                 }
@@ -315,4 +315,18 @@ public class NpgsqlLTreeTranslator : IMethodCallTranslator, IMemberTranslator
         SqlExpression Visit(Expression expression)
             => (SqlExpression)sqlTranslatingExpressionVisitor.Visit(expression);
     }
+
+    // Applying e.g. the LQuery type mapping on a function operator is a bit tricky.
+    // If it's a constant, we can just apply the mapping: the constant will get rendered as an untyped string literal, and PG will
+    // coerce it as the function parameter.
+    // If it's a parameter, we can also just apply the mapping (which causes NpgsqlDbType to be set to LQuery).
+    // For anything else, we may need an explicit cast to LQuery, e.g. a plain text column or a concatenation between strings;
+    // apply the default type mapping and then apply an additional Convert node if the resulting mapping isn't what we need.
+    private SqlExpression ApplyTypeMappingOrConvert(SqlExpression sqlExpression, RelationalTypeMapping typeMapping)
+        => sqlExpression is SqlConstantExpression or SqlParameterExpression
+            ? _sqlExpressionFactory.ApplyTypeMapping(sqlExpression, typeMapping)
+            : _sqlExpressionFactory.ApplyDefaultTypeMapping(sqlExpression) is var expressionWithDefaultTypeMapping
+            && expressionWithDefaultTypeMapping.TypeMapping!.StoreType == typeMapping.StoreType
+                ? expressionWithDefaultTypeMapping
+                : _sqlExpressionFactory.Convert(expressionWithDefaultTypeMapping, typeMapping.ClrType, typeMapping);
 }
\ No newline at end of file

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

@@ -128,13 +128,44 @@ public void LTree_matches_LQuery()
         Assert.Equal(4, entity.Id);
         AssertSql(
 """
-SELECT l."Id", l."Path", l."PathAsString"
+SELECT l."Id", l."Path", l."PathAsString", l."SomeString"
 FROM "LTreeEntities" AS l
 WHERE l."Path" ~ '*.Astrophysics'
 LIMIT 2
 """);
     }
 
+    [ConditionalFact] // #2487
+    public void LTree_matches_LQuery_with_string_column()
+    {
+        using var ctx = CreateContext();
+        var entity = ctx.LTreeEntities.Single(l => l.Path.MatchesLQuery(l.SomeString));
+
+        Assert.Equal(4, entity.Id);
+        AssertSql(
+"""
+SELECT l."Id", l."Path", l."PathAsString", l."SomeString"
+FROM "LTreeEntities" AS l
+WHERE l."Path" ~ l."SomeString"::lquery
+LIMIT 2
+""");
+    }
+
+    [ConditionalFact] // #2487
+    public void LTree_matches_LQuery_with_concat()
+    {
+        using var ctx = CreateContext();
+        var count = ctx.LTreeEntities.Count(l => l.Path.MatchesLQuery("*.Astrophysics." + l.Id));
+
+        Assert.Equal(0, count);
+        AssertSql(
+"""
+SELECT count(*)::int
+FROM "LTreeEntities" AS l
+WHERE l."Path" ~ CAST(('*.Astrophysics.' || l."Id"::text) AS lquery)
+""");
+    }
+
     [ConditionalFact]
     public void LTree_matches_any_LQuery()
     {
@@ -147,7 +178,7 @@ public void LTree_matches_any_LQuery()
 """
 @__lqueries_0={ '*.Astrophysics', '*.Geology' } (DbType = Object)
 
-SELECT l."Id", l."Path", l."PathAsString"
+SELECT l."Id", l."Path", l."PathAsString", l."SomeString"
 FROM "LTreeEntities" AS l
 WHERE l."Path" ? @__lqueries_0
 LIMIT 2
@@ -178,7 +209,7 @@ public void LTree_concat()
         Assert.Equal(2, entity.Id);
         AssertSql(
 """
-SELECT l."Id", l."Path", l."PathAsString"
+SELECT l."Id", l."Path", l."PathAsString", l."SomeString"
 FROM "LTreeEntities" AS l
 WHERE (l."Path"::text || '.Astronomy') = 'Top.Science.Astronomy'
 LIMIT 2
@@ -395,7 +426,7 @@ public void Subpath2()
         Assert.Equal(4, result.Id);
         AssertSql(
 """
-SELECT l."Id", l."Path", l."PathAsString"
+SELECT l."Id", l."Path", l."PathAsString", l."SomeString"
 FROM "LTreeEntities" AS l
 WHERE nlevel(l."Path") > 2 AND subpath(l."Path", 2) = 'Astronomy.Astrophysics'
 LIMIT 2
@@ -495,6 +526,7 @@ public static void Seed(LTreeQueryContext context)
             foreach (var ltreeEntity in ltreeEntities)
             {
                 ltreeEntity.PathAsString = ltreeEntity.Path;
+                ltreeEntity.SomeString = "*.Astrophysics";
             }
 
             context.LTreeEntities.AddRange(ltreeEntities);
@@ -512,6 +544,9 @@ public class LTreeEntity
         [Required]
         [Column(TypeName = "ltree")]
         public string PathAsString { get; set; }
+
+        [Required]
+        public string SomeString { get; set; }
     }
 
     public class LTreeQueryFixture : SharedStoreFixtureBase<LTreeQueryContext>