Handle unexpected exception due to column type change in datasource (#2681)

## Why make this change?
When an API owner starts up DAB, the GraphQL data types for the fields
are automatically derived from the SQL column types. However, if the API
owner later changes the column type without restarting DAB, the requests
will fail at runtime due to failure with parsing the JSON result in the
leaf node resolver.
Due to the unhandled exception, this will result in an error message
`One of the identified items was in an invalid format` or `"The
requested operation requires an element of type 'Number', but the target
element has type 'String'.`

## What is this change?
1. Wrap the field value parsing to catch specific exception types and
throw a clearer exception
2. Ensure location and path in errors are retained for
DataApiBuilderException for 4xx status codes

## How was this tested?

- [x] Manual test
- [] Integration Tests
- [] Unit Tests

## Sample Request(s)

Step 1: Create sample table in datasource
```
-- Create the table
CREATE TABLE Employees (
    EmployeeID INT PRIMARY KEY,
    Age INT NOT NULL,
    Salary INT NOT NULL
);

-- Insert sample data
INSERT INTO Employees (EmployeeID, Age, Salary)
VALUES 
    (1, 25, 50000),
    (2, 30, 60000),
    (3, 35, 70000),
    (4, 40, 80000),
    (5, 45, 90000);
```

Step 2:
Configure dab config with following entity
```
    "Employees": {
      "source": {
        "object": "dbo.Employees",
        "type": "table"
      },
      "permissions": [
        {
          "role": "anonymous",
          "actions": [
            {
              "action": "*"
            }
          ]
        }
      ]
    }, 
```

Verify employees query runs fine with Salary field
```
{
    employees {
        items {
            EmployeeID
            Salary
        }
    }
}
```

Step 3: Update Salary column type
```
ALTER TABLE Employees
ALTER COLUMN Salary NVARCHAR(100);
```

Run employees query again, response returned
```
{
  "errors": [
    {
      "message": "The value could not be parsed for configured GraphQL data type Int",
      "locations": [
        {
          "line": 5,
          "column": 13
        }
      ],
      "path": [
        "employees",
        "items",
        0,
        "Salary"
      ],
      "extensions": {
        "code": "GraphQLMapping"
      }
    }, 
    ...
  ]
}
```

Author: vadeveka

src/Config/Utilities/HttpStatusCodeExtensions.cs

@@ -0,0 +1,20 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using System.Net;
+
+namespace Azure.DataApiBuilder.Config.Utilities;
+
+public static class HttpStatusCodeExtensions
+{
+    /// <summary>
+    /// Check for status code within 4xx range
+    /// </summary>
+    /// <param name="statusCode"></param>
+    /// <returns></returns>
+    public static bool IsClientError(this HttpStatusCode statusCode)
+    {
+        int code = (int)statusCode;
+        return code >= 400 && code < 500;
+    }
+}

src/Core/Services/ExecutionHelper.cs

@@ -2,12 +2,14 @@
 // Licensed under the MIT License.
 
 using System.Globalization;
+using System.Net;
 using System.Text.Json;
 using Azure.DataApiBuilder.Config.ObjectModel;
 using Azure.DataApiBuilder.Core.Configurations;
 using Azure.DataApiBuilder.Core.Models;
 using Azure.DataApiBuilder.Core.Resolvers;
 using Azure.DataApiBuilder.Core.Resolvers.Factories;
+using Azure.DataApiBuilder.Service.Exceptions;
 using Azure.DataApiBuilder.Service.GraphQLBuilder;
 using Azure.DataApiBuilder.Service.GraphQLBuilder.CustomScalars;
 using Azure.DataApiBuilder.Service.GraphQLBuilder.GraphQLTypes;
@@ -155,27 +157,41 @@ fieldValue.ValueKind is not (JsonValueKind.Undefined or JsonValueKind.Null))
                 // transform it into the runtime type.
                 // We also want to ensure here that we do not unnecessarily convert values to
                 // strings and then force the conversion to parse them.
-                return namedType switch
+                try
                 {
-                    StringType => fieldValue.GetString(), // spec
-                    ByteType => fieldValue.GetByte(),
-                    ShortType => fieldValue.GetInt16(),
-                    IntType => fieldValue.GetInt32(), // spec
-                    LongType => fieldValue.GetInt64(),
-                    FloatType => fieldValue.GetDouble(), // spec
-                    SingleType => fieldValue.GetSingle(),
-                    DecimalType => fieldValue.GetDecimal(),
-                    DateTimeType => DateTimeOffset.TryParse(fieldValue.GetString()!, DateTimeFormatInfo.InvariantInfo, DateTimeStyles.AssumeUniversal, out DateTimeOffset date) ? date : null, // for DW when datetime is null it will be in "" (double quotes) due to stringagg parsing and hence we need to ensure parsing is correct.
-                    DateType => DateTimeOffset.TryParse(fieldValue.GetString()!, out DateTimeOffset date) ? date : null,
-                    LocalTimeType => fieldValue.GetString()!.Equals("null", StringComparison.OrdinalIgnoreCase) ? null : LocalTimePattern.ExtendedIso.Parse(fieldValue.GetString()!).Value,
-                    ByteArrayType => fieldValue.GetBytesFromBase64(),
-                    BooleanType => fieldValue.GetBoolean(), // spec
-                    UrlType => new Uri(fieldValue.GetString()!),
-                    UuidType => fieldValue.GetGuid(),
-                    TimeSpanType => TimeSpan.Parse(fieldValue.GetString()!),
-                    AnyType => fieldValue.ToString(),
-                    _ => fieldValue.GetString()
-                };
+                    return namedType switch
+                    {
+                        StringType => fieldValue.GetString(), // spec
+                        ByteType => fieldValue.GetByte(),
+                        ShortType => fieldValue.GetInt16(),
+                        IntType => fieldValue.GetInt32(), // spec
+                        LongType => fieldValue.GetInt64(),
+                        FloatType => fieldValue.GetDouble(), // spec
+                        SingleType => fieldValue.GetSingle(),
+                        DecimalType => fieldValue.GetDecimal(),
+                        DateTimeType => DateTimeOffset.TryParse(fieldValue.GetString()!, DateTimeFormatInfo.InvariantInfo, DateTimeStyles.AssumeUniversal, out DateTimeOffset date) ? date : null, // for DW when datetime is null it will be in "" (double quotes) due to stringagg parsing and hence we need to ensure parsing is correct.
+                        DateType => DateTimeOffset.TryParse(fieldValue.GetString()!, out DateTimeOffset date) ? date : null,
+                        LocalTimeType => fieldValue.GetString()!.Equals("null", StringComparison.OrdinalIgnoreCase) ? null : LocalTimePattern.ExtendedIso.Parse(fieldValue.GetString()!).Value,
+                        ByteArrayType => fieldValue.GetBytesFromBase64(),
+                        BooleanType => fieldValue.GetBoolean(), // spec
+                        UrlType => new Uri(fieldValue.GetString()!),
+                        UuidType => fieldValue.GetGuid(),
+                        TimeSpanType => TimeSpan.Parse(fieldValue.GetString()!),
+                        AnyType => fieldValue.ToString(),
+                        _ => fieldValue.GetString()
+                    };
+                }
+                catch (Exception ex) when (ex is InvalidOperationException or FormatException)
+                {
+                    // this usually means that database column type was changed since generating the GraphQL schema
+                    // for e.g. System.FormatException - One of the identified items was in an invalid format
+                    // System.InvalidOperationException - The requested operation requires an element of type 'Number', but the target element has type 'String'.
+                    throw new DataApiBuilderException(
+                        message: $"The {context.Selection.Field.Name} value could not be parsed for configured GraphQL data type {namedType.Name}",
+                        statusCode: HttpStatusCode.Conflict,
+                        subStatusCode: DataApiBuilderException.SubStatusCodes.GraphQLMapping,
+                        ex);
+                }
             }
 
             return null;

src/Service.Tests/Unittests/ConfigFileWatcherUnitTests.cs

@@ -11,7 +11,7 @@
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using Moq;
 
-namespace Azure.DataApiBuilder.Service.Tests.Unittests;
+namespace Azure.DataApiBuilder.Service.Tests.UnitTests;
 
 [TestClass]
 public class ConfigFileWatcherUnitTests

src/Service.Tests/Unittests/MultiSourceQueryExecutionUnitTests.cs

@@ -34,7 +34,7 @@
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using Moq;
 
-namespace Azure.DataApiBuilder.Service.Tests.Unittests
+namespace Azure.DataApiBuilder.Service.Tests.UnitTests
 {
     [TestClass]
     public class MultiSourceQueryExecutionUnitTests

src/Service.Tests/Unittests/MultipleCreateUnitTests/MsSqlMultipleCreateOrderHelperUnitTests.cs

@@ -4,7 +4,7 @@
 using System.Threading.Tasks;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 
-namespace Azure.DataApiBuilder.Service.Tests.Unittests
+namespace Azure.DataApiBuilder.Service.Tests.UnitTests
 {
     [TestClass, TestCategory(TestCategory.MSSQL)]
     public class MsSqlMultipleCreateOrderHelperUnitTests : MultipleCreateOrderHelperUnitTests

src/Service.Tests/Unittests/MultipleCreateUnitTests/MultipleCreateOrderHelperUnitTests.cs

@@ -12,7 +12,7 @@
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using Moq;
 
-namespace Azure.DataApiBuilder.Service.Tests.Unittests
+namespace Azure.DataApiBuilder.Service.Tests.UnitTests
 {
     [TestClass]
     public abstract class MultipleCreateOrderHelperUnitTests : SqlTestBase

src/Service.Tests/Unittests/MultipleCreateUnitTests/MySqlMultipleCreateOrderHelperUnitTests.cs

@@ -4,7 +4,7 @@
 using System.Threading.Tasks;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 
-namespace Azure.DataApiBuilder.Service.Tests.Unittests
+namespace Azure.DataApiBuilder.Service.Tests.UnitTests
 {
     /// <summary>
     /// Currently, we don't support multiple-create for MySql but the order determination logic for insertions is valid for MySql as well.

src/Service.Tests/Unittests/MultipleCreateUnitTests/PgSqlMultipleCreateOrderHelperUnitTests.cs

@@ -4,7 +4,7 @@
 using System.Threading.Tasks;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 
-namespace Azure.DataApiBuilder.Service.Tests.Unittests
+namespace Azure.DataApiBuilder.Service.Tests.UnitTests
 {
     /// <summary>
     /// Currently, we don't support multiple-create for PostgreSql but the order determination logic for insertions is valid for PostgreSql as well.

src/Service.Tests/Unittests/SerializationDeserializationTests.cs

@@ -13,7 +13,7 @@
 using Azure.DataApiBuilder.Core.Services.MetadataProviders.Converters;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 
-namespace Azure.DataApiBuilder.Service.Tests.Unittests
+namespace Azure.DataApiBuilder.Service.Tests.UnitTests
 {
     [TestClass]
     [TestCategory("Serialization and Deserialization using SqlMetadataProvider converters")]

src/Service/Startup.cs

@@ -9,6 +9,7 @@
 using Azure.DataApiBuilder.Config;
 using Azure.DataApiBuilder.Config.Converters;
 using Azure.DataApiBuilder.Config.ObjectModel;
+using Azure.DataApiBuilder.Config.Utilities;
 using Azure.DataApiBuilder.Core.AuthenticationHelpers;
 using Azure.DataApiBuilder.Core.AuthenticationHelpers.AuthenticationSimulator;
 using Azure.DataApiBuilder.Core.Authorization;
@@ -377,11 +378,16 @@ private void AddGraphQLService(IServiceCollection services, GraphQLRuntimeOption
                 {
                     if (error.Exception is DataApiBuilderException thrownException)
                     {
-                        return error.RemoveException()
-                                .RemoveLocations()
-                                .RemovePath()
+                        error = error.RemoveException()
                                 .WithMessage(thrownException.Message)
                                 .WithCode($"{thrownException.SubStatusCode}");
+
+                        // If user error i.e. validation error or conflict error with datasource, then retain location/path
+                        if (!thrownException.StatusCode.IsClientError())
+                        {
+                            error = error.RemoveLocations()
+                                .RemovePath();
+                        }
                     }
 
                     return error;