Merge pull request #22 from TylerReid/tryGetPropertyTypeErrorMessage

Improve error message when PropertyName is not found in properties, but the default conversion of property_name is

doc/readme.md

@@ -62,7 +62,7 @@ The mapping comes with a few requirements and is highly customizable:
   - Can ignore properties via attributes (`JsonIgnore`, `DataMemberIgnore`). These attributes can be configured in `TomlModelOptions.AttributeListForIgnore`
   - By default property names are lowered and split by `_` by PascalCase letters
     - For example: `ThisIsAnExample` becomes `this_is_an_example`
-    - This behavior can be change by passing a `TomlModelOptions` and specifying the `TomlModelOptions.GetPropertyName` delegate.
+    - This behavior can be changed by passing a `TomlModelOptions` and specifying the `TomlModelOptions.GetPropertyName` delegate.
     - If the property contains a special attribute (e.g `JsonPropertyName`, `DataMember`), it will use this name instead. You can control the list of attributes in `TomlModelOptions.AttributeListForGetName`.
 - Requires class types to have a parameter-less constructor.
 - Supports all C# primitive types, `string`, `DateTime`, `DateTimeOffset` and `TomlDateTime`.

src/Tomlyn/Model/Accessors/StandardObjectDynamicAccessor.cs

@@ -154,6 +154,12 @@ public override bool TryGetPropertyType(SourceSpan span, string name, out Type?
             propertyType = prop.PropertyType;
             return true;
         }
+        var snakeCasedName = TomlModelOptions.PascalToSnakeCase(name);
+        if (_props.ContainsKey(snakeCasedName))
+        {
+            Context.Diagnostics.Error(span, $"The property {name} was not found, but {snakeCasedName} was. By default property names are lowered and split by _ by PascalCase letters. This behavior can be changed by passing a TomlModelOptions and specifying the TomlModelOptions.GetPropertyName delegate.");
+            return false;
+        }
         Context.Diagnostics.Error(span, $"The property {name} was not found on object type {TargetType.FullName}");
         return false;
     }

src/Tomlyn/TomlModelOptions.cs

@@ -95,8 +95,11 @@ public TomlModelOptions()
             }
         }
 
-        name ??= prop.Name;
+        return PascalToSnakeCase(name ?? prop.Name);
+    }
 
+    internal static string PascalToSnakeCase(string name)
+    {
         var builder = new StringBuilder();
         var pc = (char)0;
         foreach (var c in name)