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c# - Serialize Property, but Do Not Deserialize Property in Json.Net

While I've found plenty of approaches to deserializing specific properties while preventing them from serializing, I'm looking for the opposite behavior.

I've found plenty of questions asking the inverse:

Making a property deserialize but not serialize with json.net

Can I instruct Json.NET to deserialize, but not serialize, specific properties?

JSON.Net - Use JsonIgnoreAttribute only on serialization (But not when deserialzing)

How can I serialize a specific property, but prevent it from deserializing back to the POCO? Is there an attribute I can use to decorate the specific property?

Basically I'm looking for an equivalent to the ShouldSerialize* methods for deserialization.

I know I can write a custom converter, but that seems like overkill for this.

Edit:

Here's a little more context. The reason behind this is my class looks like:

public class Address : IAddress
{
    /// <summary>
    /// Gets or sets the two character country code
    /// </summary>
    [JsonProperty("countryCode")]
    [Required]
    public string CountryCode { get; set; }

    /// <summary>
    /// Gets or sets the country code, and province or state code delimited by a vertical pipe: <c>US|MI</c>
    /// </summary>
    [JsonProperty("countryProvinceState")]
    public string CountryProvinceState
    {
        get
        {
            return string.Format("{0}|{1}", this.CountryCode, this.ProvinceState);
        }
        set
        {
            if (!string.IsNullOrWhiteSpace(value) && value.Contains("|"))
            {
                string[] valueParts = value.Split('|');
                if (valueParts.Length == 2)
                {
                    this.CountryCode = valueParts[0];
                    this.ProvinceState = valueParts[1];
                }
            }
        }
    }

    [JsonProperty("provinceState")]
    [Required]
    public string ProvinceState { get; set; }
}

I need the CountryProvinceState property for the request, but I don't want it to deserialize back and trigger the setter logic.

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1 Answer

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Simplest method would be to mark the real property as [JsonIgnore] and create a get-only proxy property:

    /// <summary>
    /// Gets or sets the country code, and province or state code delimited by a vertical pipe: <c>US|MI</c>
    /// </summary>
    [JsonIgnore]
    public string CountryProvinceState
    {
        get
        {
            return string.Format("{0}|{1}", this.CountryCode, this.ProvinceState);
        }
        set
        {
            if (!string.IsNullOrWhiteSpace(value) && value.Contains("|"))
            {
                string[] valueParts = value.Split('|');
                if (valueParts.Length == 2)
                {
                    this.CountryCode = valueParts[0];
                    this.ProvinceState = valueParts[1];
                }
            }
        }
    }

    [JsonProperty("countryProvinceState")]
    string ReadCountryProvinceState
    {
        get { return CountryProvinceState; } 
    }

The proxy property can be private if you desire.

Update

If you have to do this for lots of properties in lots of classes, it might be easier to create your own ContractResolver that checks for a custom attribute. If found, the attribute would signal that the property is get-only:

[System.AttributeUsage(System.AttributeTargets.Property, AllowMultiple = false)]
public class GetOnlyJsonPropertyAttribute : Attribute
{
}

public class GetOnlyContractResolver : DefaultContractResolver
{
    protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization)
    {
        var property = base.CreateProperty(member, memberSerialization);
        if (property != null && property.Writable)
        {
            var attributes = property.AttributeProvider.GetAttributes(typeof(GetOnlyJsonPropertyAttribute), true);
            if (attributes != null && attributes.Count > 0)
                property.Writable = false;
        }
        return property;
    }
}

Then use it like:

[JsonProperty("countryProvinceState")]
[GetOnlyJsonProperty]
public string CountryProvinceState { get; set; }

And then:

        var settings = new JsonSerializerSettings { ContractResolver = new GetOnlyContractResolver() };

        var address = JsonConvert.DeserializeObject<Address>(jsonString, settings);

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