Encapsulating multiple dictionaries parsed from DbDataReader handler into a class

src/Service/Models/DbOperationResultRow.cs

@@ -0,0 +1,31 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using System.Collections.Generic;
+
+namespace Azure.DataApiBuilder.Service.Models
+{
+    /// <summary>
+    /// Represents a single row read from DbDataReader.
+    /// </summary>
+    public class DbOperationResultRow
+    {
+        public DbOperationResultRow(
+            Dictionary<string, object?> columns,
+            Dictionary<string, object> resultProperties)
+        {
+            this.Columns = columns;
+            this.ResultProperties = resultProperties;
+        }
+
+        /// <summary>
+        /// Represents a result set row in <c>ColumnName: Value</c> format, empty if no row was found.
+        /// </summary>
+        public Dictionary<string, object?> Columns { get; private set; }
+
+        /// <summary>
+        /// Represents DbDataReader properties such as RecordsAffected and HasRows.
+        /// </summary>
+        public Dictionary<string, object> ResultProperties { get; private set; }
+    }
+}

src/Service/Resolvers/IQueryExecutor.cs

@@ -6,6 +6,7 @@
 using System.Data.Common;
 using System.Text.Json.Nodes;
 using System.Threading.Tasks;
+using Azure.DataApiBuilder.Service.Models;
 using Microsoft.AspNetCore.Http;
 
 namespace Azure.DataApiBuilder.Service.Resolvers
@@ -30,7 +31,7 @@ public interface IQueryExecutor
         public Task<TResult?> ExecuteQueryAsync<TResult>(
             string sqltext,
             IDictionary<string, object?> parameters,
-            Func<DbDataReader, List<string>?, Task<TResult?>>? dataReaderHandler,
+            Func<DbDataReader, List<string>?, Task<TResult>>? dataReaderHandler,
             HttpContext? httpContext = null,
             List<string>? args = null);
 
@@ -41,7 +42,7 @@ public interface IQueryExecutor
         /// <param name="dbDataReader">A DbDataReader.</param>
         /// <param name="args">List of string arguments if any.</param>
         /// <returns>A JsonArray with each element corresponding to the row (ColumnName : columnValue) in the dbDataReader.</returns>
-        public Task<JsonArray?> GetJsonArrayAsync(
+        public Task<JsonArray> GetJsonArrayAsync(
             DbDataReader dbDataReader,
             List<string>? args = null);
 
@@ -62,10 +63,8 @@ public interface IQueryExecutor
         /// </summary>
         /// <param name="dbDataReader">A DbDataReader</param>
         /// <param name="args">List of columns to extract. Extracts all if unspecified.</param>
-        /// <returns>A tuple of 2 dictionaries:
-        /// 1. A dictionary representing the row in <c>ColumnName: Value</c> format, null if no row was found
-        /// 2. A dictionary of properties of the Db Data Reader like RecordsAffected, HasRows.</returns>
-        public Task<Tuple<Dictionary<string, object?>?, Dictionary<string, object>>?> ExtractRowFromDbDataReader(
+        /// <returns>Single row read from DbDataReader.</returns>
+        public Task<DbOperationResultRow> ExtractRowFromDbDataReader(
                 DbDataReader dbDataReader,
                 List<string>? args = null);
 
@@ -76,11 +75,10 @@ public interface IQueryExecutor
         /// </summary>
         /// <param name="dbDataReader">A DbDataReader.</param>
         /// <param name="args">The arguments to this handler - args[0] = primary key in pretty format, args[1] = entity name.</param>
-        /// <returns>A tuple of 2 dictionaries:
-        /// 1. A dictionary representing the row in <c>ColumnName: Value</c> format.
-        /// 2. A dictionary of properties of the DbDataReader like RecordsAffected, HasRows.
-        /// If the first result set is being returned, has the property "IsFirstResultSet" set to true in this dictionary.</returns>
-        public Task<Tuple<Dictionary<string, object?>?, Dictionary<string, object>>?> GetMultipleResultSetsIfAnyAsync(
+        /// <returns>Single row read from DbDataReader.
+        /// If the first result set is being returned, DbOperationResultRow.ResultProperties dictionary has
+        /// the property "IsFirstResultSet" set to true.</returns>
+        public Task<DbOperationResultRow> GetMultipleResultSetsIfAnyAsync(
                 DbDataReader dbDataReader,
                 List<string>? args = null);
 
@@ -90,7 +88,7 @@ public interface IQueryExecutor
         /// <param name="dbDataReader">A DbDataReader.</param>
         /// <param name="args">List of string arguments if any.</param>
         /// <returns>A dictionary of properties of the DbDataReader like RecordsAffected, HasRows.</returns>
-        public Task<Dictionary<string, object>?> GetResultProperties(
+        public Task<Dictionary<string, object>> GetResultProperties(
                 DbDataReader dbDataReader,
                 List<string>? args = null);
 

src/Service/Resolvers/QueryExecutor.cs

@@ -12,6 +12,7 @@
 using System.Threading.Tasks;
 using Azure.DataApiBuilder.Service.Configurations;
 using Azure.DataApiBuilder.Service.Exceptions;
+using Azure.DataApiBuilder.Service.Models;
 using Microsoft.AspNetCore.Http;
 using Microsoft.Extensions.Logging;
 using Polly;
@@ -62,7 +63,7 @@ public QueryExecutor(DbExceptionParser dbExceptionParser,
         public virtual async Task<TResult?> ExecuteQueryAsync<TResult>(
             string sqltext,
             IDictionary<string, object?> parameters,
-            Func<DbDataReader, List<string>?, Task<TResult?>>? dataReaderHandler,
+            Func<DbDataReader, List<string>?, Task<TResult>>? dataReaderHandler,
             HttpContext? httpContext = null,
             List<string>? args = null)
         {
@@ -134,7 +135,7 @@ await ExecuteQueryAgainstDbAsync(conn,
             TConnection conn,
             string sqltext,
             IDictionary<string, object?> parameters,
-            Func<DbDataReader, List<string>?, Task<TResult?>>? dataReaderHandler,
+            Func<DbDataReader, List<string>?, Task<TResult>>? dataReaderHandler,
             HttpContext? httpContext,
             List<string>? args = null)
         {
@@ -208,20 +209,20 @@ public async Task<bool> ReadAsync(DbDataReader reader)
         }
 
         /// <inheritdoc />
-        public async Task<Tuple<Dictionary<string, object?>?, Dictionary<string, object>>?>
+        public async Task<DbOperationResultRow>
             ExtractRowFromDbDataReader(DbDataReader dbDataReader, List<string>? args = null)
         {
-            Dictionary<string, object?> row = new();
-
-            Dictionary<string, object> propertiesOfResult = GetResultProperties(dbDataReader).Result ?? new();
+            DbOperationResultRow dbOperationResultRow = new(
+                columns: new(),
+                resultProperties: GetResultProperties(dbDataReader).Result ?? new());
 
             if (await ReadAsync(dbDataReader))
             {
                 if (dbDataReader.HasRows)
                 {
                     DataTable? schemaTable = dbDataReader.GetSchemaTable();
 
-                    if (schemaTable != null)
+                    if (schemaTable is not null)
                     {
                         foreach (DataRow schemaRow in schemaTable.Rows)
                         {
@@ -235,43 +236,37 @@ public async Task<bool> ReadAsync(DbDataReader reader)
                             int colIndex = dbDataReader.GetOrdinal(columnName);
                             if (!dbDataReader.IsDBNull(colIndex))
                             {
-                                row.Add(columnName, dbDataReader[columnName]);
+                                dbOperationResultRow.Columns.Add(columnName, dbDataReader[columnName]);
                             }
                             else
                             {
-                                row.Add(columnName, value: null);
+                                dbOperationResultRow.Columns.Add(columnName, value: null);
                             }
                         }
                     }
                 }
             }
 
-            // no row was read
-            if (row.Count == 0)
-            {
-                return new Tuple<Dictionary<string, object?>?, Dictionary<string, object>>(null, propertiesOfResult);
-            }
-
-            return new Tuple<Dictionary<string, object?>?, Dictionary<string, object>>(row, propertiesOfResult);
+            return dbOperationResultRow;
         }
 
         /// <inheritdoc />
         /// <Note>This function is a DbDataReader handler of type Func<DbDataReader, List<string>?, Task<TResult?>>
         /// The parameter args is not used but is added to conform to the signature of the DbDataReader handler
         /// function argument of ExecuteQueryAsync.</Note>
-        public async Task<JsonArray?> GetJsonArrayAsync(
+        public async Task<JsonArray> GetJsonArrayAsync(
             DbDataReader dbDataReader,
             List<string>? args = null)
         {
-            Tuple<Dictionary<string, object?>?, Dictionary<string, object>>? resultRowAndProperties;
+            DbOperationResultRow dbOperationResultRow = await ExtractRowFromDbDataReader(dbDataReader);
             JsonArray resultArray = new();
 
-            while ((resultRowAndProperties = await ExtractRowFromDbDataReader(dbDataReader)) is not null &&
-                resultRowAndProperties.Item1 is not null)
+            while (dbOperationResultRow.Columns.Count > 0)
             {
                 JsonElement result =
-                    JsonSerializer.Deserialize<JsonElement>(JsonSerializer.Serialize(resultRowAndProperties.Item1));
+                    JsonSerializer.Deserialize<JsonElement>(JsonSerializer.Serialize(dbOperationResultRow.Columns));
                 resultArray.Add(result);
+                dbOperationResultRow = await ExtractRowFromDbDataReader(dbDataReader);
             }
 
             return resultArray;
@@ -306,21 +301,20 @@ public async Task<bool> ReadAsync(DbDataReader reader)
         /// <inheritdoc />
         /// <Note>This function is a DbDataReader handler of type
         /// Func<DbDataReader, List<string>?, Task<TResult?>></Note>
-        public async Task<Tuple<Dictionary<string, object?>?, Dictionary<string, object>>?> GetMultipleResultSetsIfAnyAsync(
+        public async Task<DbOperationResultRow> GetMultipleResultSetsIfAnyAsync(
             DbDataReader dbDataReader, List<string>? args = null)
         {
-            Tuple<Dictionary<string, object?>?, Dictionary<string, object>>? resultRecordWithProperties
+            DbOperationResultRow dbOperationResultRow
                 = await ExtractRowFromDbDataReader(dbDataReader);
 
             /// Processes a second result set from DbDataReader if it exists.
             /// In MsSQL upsert:
             /// result set #1: result of the UPDATE operation.
             /// result set #2: result of the INSERT operation.
-            if (resultRecordWithProperties is not null && resultRecordWithProperties.Item1 is not null)
+            if (dbOperationResultRow.Columns.Count > 0)
             {
-                resultRecordWithProperties.Item2.Add(SqlMutationEngine.IS_FIRST_RESULT_SET, true);
-                return new Tuple<Dictionary<string, object?>?, Dictionary<string, object>>
-                    (resultRecordWithProperties.Item1, resultRecordWithProperties.Item2);
+                dbOperationResultRow.ResultProperties.Add(SqlMutationEngine.IS_FIRST_RESULT_SET, true);
+                return dbOperationResultRow;
             }
             else if (await dbDataReader.NextResultAsync())
             {
@@ -345,20 +339,22 @@ public async Task<bool> ReadAsync(DbDataReader reader)
                 }
             }
 
-            return null;
+            return dbOperationResultRow;
         }
 
         /// <inheritdoc />
         /// <Note>This function is a DbDataReader handler of type
         /// Func<DbDataReader, List<string>?, Task<TResult?>></Note>
-        public Task<Dictionary<string, object>?> GetResultProperties(
+        public Task<Dictionary<string, object>> GetResultProperties(
             DbDataReader dbDataReader,
             List<string>? columnNames = null)
         {
-            Dictionary<string, object>? propertiesOfResult = new();
-            propertiesOfResult.Add(nameof(dbDataReader.RecordsAffected), dbDataReader.RecordsAffected);
-            propertiesOfResult.Add(nameof(dbDataReader.HasRows), dbDataReader.HasRows);
-            return Task.FromResult((Dictionary<string, object>?)propertiesOfResult);
+            Dictionary<string, object> resultProperties = new()
+            {
+                { nameof(dbDataReader.RecordsAffected), dbDataReader.RecordsAffected },
+                { nameof(dbDataReader.HasRows), dbDataReader.HasRows }
+            };
+            return Task.FromResult(resultProperties);
         }
 
         private async Task<string> GetJsonStringFromDbReader(DbDataReader dbDataReader)