C#•4y ago•

3 replies

✅ JSON Contract : modifying the value of a property, using System.Text.Json 7

Hello! I'm trying to encrypt only certain fields in a DTO before serializing them, using an attribute in the class definition. The attribute part I got the hang of, however I'm uncertain about how to go about modifying the value of a given property. Here's what I've been doing, trying to follow the tips from this dev blog : https://devblogs.microsoft.com/dotnet/system-text-json-in-dotnet-7/

- extend the

DefaultJsonTypeInfoResolver

DefaultJsonTypeInfoResolver

class
- override the

GetTypeInfo(Type, JsonSerializerOptions)

GetTypeInfo(Type, JsonSerializerOptions)

method
- in that method, 'reject' anything that isn't of Kind

JsonTypeInfoKind.Object

JsonTypeInfoKind.Object

- iterate on the

JsonPropertyInfo

JsonPropertyInfo

list returned by

JsonTypeInfo.Properties

JsonTypeInfo.Properties

- check each of the

JsonPropertyInfo.AttributeProvider

JsonPropertyInfo.AttributeProvider

to see if they are

ICustomAttributeProvider

ICustomAttributeProvider

and if my custom attribute is defined in it.

Once I've confirmed that, that is where I'm kinda lost. It's probably dumb, but I haven't managed yet to find what to do from here. I'm thinking either :
- I need to change the delegate method of

JsonPropertyInfo.Get

JsonPropertyInfo.Get

and

JsonPropertyInfo.Set

JsonPropertyInfo.Set

or
- I need to tell it here and there to take the property value and to pass it through my encryption method.

Anyone here could point me to the correct way to proceed?

Current code :

        public override JsonTypeInfo GetTypeInfo(Type type, JsonSerializerOptions options)
        {
            JsonTypeInfo typeInfo = base.GetTypeInfo(type, options);
            if (typeInfo.Kind != JsonTypeInfoKind.Object) return typeInfo;
            
            foreach (JsonPropertyInfo propertyInfo in typeInfo.Properties)
            {
                if (propertyInfo.AttributeProvider is ICustomAttributeProvider provider &&
                    provider.IsDefined(typeof(JsonEncryptAttribute), inherit: true))
                {
                    # todo : Unsure how to proceed here.
                }
            }
            return typeInfo;
        }

        public override JsonTypeInfo GetTypeInfo(Type type, JsonSerializerOptions options)
        {
            JsonTypeInfo typeInfo = base.GetTypeInfo(type, options);
            if (typeInfo.Kind != JsonTypeInfoKind.Object) return typeInfo;
            
            foreach (JsonPropertyInfo propertyInfo in typeInfo.Properties)
            {
                if (propertyInfo.AttributeProvider is ICustomAttributeProvider provider &&
                    provider.IsDefined(typeof(JsonEncryptAttribute), inherit: true))
                {
                    # todo : Unsure how to proceed here.
                }
            }
            return typeInfo;
        }

Any insight appreciated.

✅ JSON Contract : modifying the value of a property, using System.Text.Json 7

DefaultJsonTypeInfoResolver

DefaultJsonTypeInfoResolver

class
- override the

GetTypeInfo(Type, JsonSerializerOptions)

GetTypeInfo(Type, JsonSerializerOptions)

method
- in that method, 'reject' anything that isn't of Kind

JsonTypeInfoKind.Object

JsonTypeInfoKind.Object

- iterate on the

JsonPropertyInfo

JsonPropertyInfo

list returned by

JsonTypeInfo.Properties

JsonTypeInfo.Properties

- check each of the

JsonPropertyInfo.AttributeProvider

JsonPropertyInfo.AttributeProvider

to see if they are

ICustomAttributeProvider

ICustomAttributeProvider

JsonPropertyInfo.Get

JsonPropertyInfo.Get

and

JsonPropertyInfo.Set

JsonPropertyInfo.Set

or
- I need to tell it here and there to take the property value and to pass it through my encryption method.

Anyone here could point me to the correct way to proceed?

Current code :

        public override JsonTypeInfo GetTypeInfo(Type type, JsonSerializerOptions options)
        {
            JsonTypeInfo typeInfo = base.GetTypeInfo(type, options);
            if (typeInfo.Kind != JsonTypeInfoKind.Object) return typeInfo;
            
            foreach (JsonPropertyInfo propertyInfo in typeInfo.Properties)
            {
                if (propertyInfo.AttributeProvider is ICustomAttributeProvider provider &&
                    provider.IsDefined(typeof(JsonEncryptAttribute), inherit: true))
                {
                    # todo : Unsure how to proceed here.
                }
            }
            return typeInfo;
        }

        public override JsonTypeInfo GetTypeInfo(Type type, JsonSerializerOptions options)
        {
            JsonTypeInfo typeInfo = base.GetTypeInfo(type, options);
            if (typeInfo.Kind != JsonTypeInfoKind.Object) return typeInfo;
            
            foreach (JsonPropertyInfo propertyInfo in typeInfo.Properties)
            {
                if (propertyInfo.AttributeProvider is ICustomAttributeProvider provider &&
                    provider.IsDefined(typeof(JsonEncryptAttribute), inherit: true))
                {
                    # todo : Unsure how to proceed here.
                }
            }
            return typeInfo;
        }

Any insight appreciated.

✅ JSON Contract : modifying the value of a property, using System.Text.Json 7

✅ JSON Contract : modifying the value of a property, using System.Text.Json 7

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