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Json.NET boilerplate to ignore serializing empty values and "read only" properties
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| public class LeanContractResolver : DefaultContractResolver | |
| { | |
| public static LeanContractResolver Instance { get; } = new(); | |
| protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization) | |
| { | |
| var property = base.CreateProperty(member, memberSerialization); | |
| if (property.PropertyType == null) | |
| return property; | |
| if (property.UnderlyingName == null) | |
| return property; | |
| if (property.DeclaringType == null) | |
| return property; | |
| var propertyInfo = property.DeclaringType!.GetProperty(property.UnderlyingName!); | |
| if (IsReadOnlyProperty(propertyInfo) || IsExpressionBodiedProperty(property, propertyInfo)) | |
| { | |
| property.ShouldSerialize = _ => false; | |
| property.ShouldDeserialize = _ => false; | |
| } | |
| else if (property.PropertyType == typeof(string)) | |
| { | |
| property.ShouldSerialize = instance => | |
| { | |
| var value = (string)GetValue(instance, property, member); | |
| return !string.IsNullOrEmpty(value); | |
| }; | |
| } | |
| else if (property.PropertyType == typeof(DateTime)) | |
| { | |
| property.ShouldSerialize = instance => | |
| { | |
| var value = (DateTime)GetValue(instance, property, member); | |
| return value != default; | |
| }; | |
| } | |
| else if (typeof(ICollection).IsAssignableFrom(property.PropertyType)) | |
| { | |
| property.ShouldSerialize = instance => | |
| { | |
| var collection = (ICollection)GetValue(instance, property, member); | |
| return collection?.Count > 0; | |
| }; | |
| } | |
| return property; | |
| } | |
| private static object GetValue(object instance, JsonProperty property, MemberInfo member) | |
| { | |
| var type = property.DeclaringType!; | |
| var name = property.UnderlyingName!; | |
| return member.MemberType switch | |
| { | |
| MemberTypes.Property => type.GetProperty(name)!.GetValue(instance), | |
| MemberTypes.Field => type.GetField(name)!.GetValue(instance), | |
| _ => null | |
| }; | |
| } | |
| private static bool IsReadOnlyProperty(PropertyInfo propertyInfo) | |
| { | |
| if (propertyInfo == null) | |
| return false; | |
| return propertyInfo.SetMethod == null || !propertyInfo.SetMethod.IsPublic; | |
| } | |
| // An expression-bodied property is like this: | |
| // public Foo => _bar; | |
| private static bool IsExpressionBodiedProperty(JsonProperty property, PropertyInfo propertyInfo) | |
| { | |
| if (propertyInfo == null) | |
| return false; | |
| // There is no built-in reflection method to detect whether a property is expression- | |
| // bodied other than to check for the absence of a backing field. | |
| var backingField = property.DeclaringType!.GetField( | |
| $"<{property.PropertyName}>k__BackingField", | |
| BindingFlags.NonPublic | BindingFlags.Instance); | |
| return backingField == null; | |
| } | |
| } |
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