39 lines
2.7 KiB
Markdown
39 lines
2.7 KiB
Markdown
# Custom Serialization
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_<small>Documentation pages for `BitBadger.Npgsql.Documents` redirect here. This library replaced it as of v3; see project home if this applies to you.</small>_
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JSON documents are sent to and received from both PostgreSQL and SQLite as `string`s; the translation to and from your domain objects (commonly called <abbr title="Plain Old CLR Objects">POCO</abbr>s) is handled via .NET. By default, the serializer used by the library is based on `System.Text.Json` with [converters for common F# types][fs].
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## Implementing a Custom Serializer
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`IDocumentSerializer` (found in the `BitBadger.Documents` namespace) specifies two methods. `Serialize<T>` takes a `T` and returns a `string`; `Deserialize<T>` takes a `string` and returns an instance of `T`. (These show as `'T` in F#.) While implementing those two methods is required, the custom implementation can use whatever library you desire, and contain converters for custom types.
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Once this serializer is implemented and constructed, provide it to the library:
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```csharp
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// C#
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var serializer = /* constructed serializer */;
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Configuration.UseSerializer(serializer);
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```
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```fsharp
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// F#
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let serializer = (* constructed serializer *)
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Configuration.useSerializer serializer
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```
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The biggest benefit to registering a serializer (apart from control) is that all JSON operations will use the same serializer. This is most important for PostgreSQL's JSON containment queries; the object you pass as the criteria will be translated properly before it is compared. However, "unstructured" data does not mean "inconsistently structured" data; if your application uses custom serialization, extending this to your documents ensures that the structure is internally consistent.
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## Uses for Custom Serialization
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- If you use a custom serializer (or serializer options) in your application, a custom serializer implementation can utilize these existing configuration options.
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- If you prefer [`Newtonsoft.Json`][nj], you can wrap `JsonConvert` or `JsonSerializer` calls in a custom converter. F# users may consider incorporating Microsoft's [`FSharpLu.Json`][fj] converter.
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- If your project uses [`NodaTime`][], your custom serializer could include its converters for `System.Text.Json` or `Newtonsoft.Json`.
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- If you use <abbr title="Domain Driven Design">DDD</abbr> to define custom types, you can implement converters to translate them to/from your preferred JSON representation.
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[fs]: https://github.com/Tarmil/FSharp.SystemTextJson "FSharp.SystemTextJson • GitHub"
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[nj]: https://www.newtonsoft.com/json "Json.NET"
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[fj]: https://github.com/microsoft/fsharplu/blob/main/FSharpLu.Json.md "FSharpLu.Json • GitHub"
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[`NodaTime`]: https://nodatime.org/ "NodaTime"
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