How to override the JsonPropertyName while serializing?

[akshay-zz]

The doc talks about how we can change the name of the JSON property name. Also how we can create our own PropertyNamingPolicy. But how can we override the JsonPropertyName while serializing? Is there any way to do it?

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• ID: 7bee4ecb-7464-b321-937a-e6d4586556eb
• Version Independent ID: 27c18218-d28f-a524-b7e1-8262005b7026
• Content: How to customize property names and values with System.Text.Json - .NET
• Content Source: docs/standard/serialization/system-text-json/customize-properties.md
• Product: dotnet-fundamentals
• GitHub Login: @gewarren
• Microsoft Alias: gewarren

[gewarren]

What is the scenario? Couldn't you just remove or update the attribute?

[akshay-zz]

Yep, In actual property I could not change the property attribute. Looking for a way to simply override it. For my case, I want to have lowercase names instead of what we have kept in the attribute(came case) when I serialize the model.

[gewarren]

You can probably do that with a custom contract that modifies JsonPropertyInfo.Get, although I haven't tested it out. @eiriktsarpalis is the expert in this area.

[eiriktsarpalis]

If you're simply looking to convert property names to uppercase you might be able to just configure the JsonSerializerOptions.PropertyNamingPolicy property with a JsonNamingPolicy that performs that conversion.

[akshay-zz]

@eiriktsarpalis This will not work as it will get overridden by JsonPropertyName. I have tried that not working. Also, it is mentioned in the docs also.

The JSON property naming policy:

Applies to serialization and deserialization.
Is overridden by [JsonPropertyName] attributes. This is why the JSON property name Wind in the example is not upper case

[eiriktsarpalis]

If the property already has JsonPropertyName annotations that you cannot remove, then writing a contract customizer that updates the relevant JsonPropertyInfo.Name property is your best bet. Perhaps authoring your own DTO type might be even simpler though.