Populate DbType for PostgreSql

src/Core/Models/GraphQLFilterParsers.cs

@@ -706,7 +706,7 @@ public static Predicate Parse(
             predicates.Push(new PredicateOperand(new Predicate(
                 new PredicateOperand(column),
                 op,
-                GenerateRightOperand(ctx, argumentObject, name, processLiterals, value, processLiteral) // right operand
+                GenerateRightOperand(ctx, argumentObject, name, processLiterals, value, processLiteral, column.ColumnName) // right operand
                 )));
         }
 
@@ -760,14 +760,16 @@ public static Predicate Parse(
     /// <param name="processLiterals">A function to encode or parameterize literal values for database queries.</param>
     /// <param name="value">The value to be used as the right operand in the predicate.</param>
     /// <param name="processLiteral">Indicates whether to process the value as a literal using processLiterals, or use its string representation directly.</param>
+    /// <param name="columnName">The name of the column being filtered, used to look up the column's DbType for proper parameter typing.</param>
     /// <returns>A <see cref="PredicateOperand"/> representing the right operand for the predicate.</returns>
     private static PredicateOperand GenerateRightOperand(
     IMiddlewareContext ctx,
     InputObjectType argumentObject,
     string operationName,
     Func<object, string?, string> processLiterals,
     object value,
-    bool processLiteral)
+    bool processLiteral,
+    string? columnName)
     {
         if (operationName.Equals("in", StringComparison.OrdinalIgnoreCase))
         {
@@ -777,13 +779,13 @@ private static PredicateOperand GenerateRightOperand(
                     argumentObject.Fields[operationName],
                     ctx.Variables))
                 .Where(inValue => inValue is not null)
-                .Select(inValue => processLiterals(inValue!, null))
+                .Select(inValue => processLiterals(inValue!, columnName))
                 .ToList();
 
             return new PredicateOperand("(" + string.Join(", ", encodedParams) + ")");
         }
 
-        return new PredicateOperand(processLiteral ? processLiterals(value, null) : value.ToString());
+        return new PredicateOperand(processLiteral ? processLiterals(value, columnName) : value.ToString());
     }
 
     private static string EscapeLikeString(string input)

src/Core/Resolvers/IQueryExecutor.cs

@@ -165,7 +165,7 @@ public Dictionary<string, object> GetResultProperties(
         public string GetSessionParamsQuery(HttpContext? httpContext, IDictionary<string, DbConnectionParam> parameters, string dataSourceName);
 
         /// <summary>
-        /// Helper method to populate DbType for parameter. Currently DbTypes for parameters are only populated for MsSql.
+        /// Helper method to populate DbType for parameter. Currently DbTypes for parameters are only populated for MsSql and PostgreSql.
         /// </summary>
         /// <param name="parameterEntry">Entry corresponding to current database parameter to be created.</param>
         /// <param name="parameter">Parameter sent to database.</param>

src/Core/Resolvers/PostgreSqlExecutor.cs

@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT License.
 
+using System.Data;
 using System.Data.Common;
 using Azure.Core;
 using Azure.DataApiBuilder.Config;
@@ -146,6 +147,15 @@ private static bool ShouldManagedIdentityAccessBeAttempted(NpgsqlConnectionStrin
             return string.IsNullOrEmpty(builder.Password);
         }
 
+        /// <inheritdoc/>
+        public static void PopulateDbTypeForParameter(KeyValuePair<string, DbConnectionParam> parameterEntry, DbParameter parameter)
+        {
+            if (parameterEntry.Value is not null && parameterEntry.Value.DbType is not null)
+            {
+                parameter.DbType = (DbType)parameterEntry.Value.DbType;
+            }
+        }
+
         /// <summary>
         /// Determines if the saved default azure credential's access token is valid and not expired.
         /// </summary>

src/Core/Resolvers/QueryExecutor.cs

@@ -420,7 +420,7 @@ public virtual string GetSessionParamsQuery(HttpContext? httpContext, IDictionar
         /// <inheritdoc/>
         public virtual void PopulateDbTypeForParameter(KeyValuePair<string, DbConnectionParam> parameterEntry, DbParameter parameter)
         {
-            // DbType for parameter is currently only populated for MsSql which has its own overridden implementation.
+            // DbType for parameter is currently only populated for MsSql and PostgreSql which has its own overridden implementation.
             return;
         }