Improve Invalid GraphQL Name message

src/Core/Services/MetadataProviders/SqlMetadataProvider.cs

@@ -1474,7 +1474,7 @@ private async Task PopulateSourceDefinitionAsync(
                     && IsGraphQLReservedName(entity, columnName, graphQLEnabledGlobally: runtimeConfig.IsGraphQLEnabled))
                 {
                     throw new DataApiBuilderException(
-                       message: $"The column '{columnName}' violates GraphQL name restrictions.",
+                       message: $"The column '{columnName}' from '{entityName}' violates GraphQL name restrictions.",
                        statusCode: HttpStatusCode.ServiceUnavailable,
                        subStatusCode: DataApiBuilderException.SubStatusCodes.ErrorInInitialization);
                 }
@@ -1584,7 +1584,8 @@ public static bool IsGraphQLReservedName(Entity entity, string databaseColumnNam
                         }
                     }
 
-                    return IsIntrospectionField(databaseColumnName);
+                    // Possible naming violations are if the field starts with '__' or if it contains whitespace characters.
+                    return IsIntrospectionField(databaseColumnName) || IsGraphQLNameWhiteSpace(databaseColumnName);
                 }
             }
 

src/Service.GraphQLBuilder/GraphQLNaming.cs

@@ -28,6 +28,8 @@ public static class GraphQLNaming
         /// <seealso cref="https://spec.graphql.org/October2021/#sec-Names.Reserved-Names"/>
         public const string INTROSPECTION_FIELD_PREFIX = "__";
 
+        public const string INVALID_EMPTY_SPACE = " ";
+
         public const string LINKING_OBJECT_PREFIX = "linkingObject";
 
         public const string PK_QUERY_SUFFIX = "_by_pk";
@@ -96,6 +98,20 @@ public static bool IsIntrospectionField(string fieldName)
             return fieldName.StartsWith(INTROSPECTION_FIELD_PREFIX, StringComparison.Ordinal);
         }
 
+        /// <summary>
+        /// Per GraphQL specification:
+        /// A name can only start with a letter or an underscore, and can only
+        /// contain letters, numbers, and underscores. It is not able to contain whitespaces
+        /// This helper function identifies whether the provided name contains whitespaces.
+        /// </summary>
+        /// <seealso cref="https://spec.graphql.org/October2021/#sec-Names"/>
+        /// <param name="fieldName">Field name to evaluate</param>
+        /// <returns>True/False</returns>
+        public static bool IsGraphQLNameWhiteSpace(string fieldName)
+        {
+            return fieldName.Contains(INVALID_EMPTY_SPACE, StringComparison.Ordinal);
+        }
+
         /// <summary>
         /// Attempts to deserialize and get the SingularPlural GraphQL naming config
         /// of an Entity from the Runtime Configuration and return the singular name of the entity.

src/Service.Tests/Configuration/ConfigurationTests.cs

@@ -5651,7 +5651,7 @@ public async Task TestAutoentitiesWithSameObjectDifferentSchemas()
                     "PublisherAutoEntity", new Autoentity(
                         Patterns: new AutoentityPatterns(
                             Include: null,
-                            Exclude: new[] { "dbo.GQLmappings", "dbo.graphql_incompatible", "dbo.brokers" },
+                            Exclude: new[] { "dbo.GQLmappings", "dbo.brokers" },
                             Name: null
                         ),
                         Template: new AutoentityTemplate(