Use Specific json.Unmarshaler for a dynamic JSON

[dc0d]

Target: Assuming we want to deserialize some JSON dynamically and we want to unmarshal some fields using specific unmarshaling code (a certain UnmarshalJSON). The problem is using something like map[string]interface{} there is no way to specify that.

Thought Experiment: I like to have something like:

ourUnmarshaler.AddField("name", func() json.Unmarshaler /* default field creator for unmarshaling */, /* other options like omitempty */)

or perhaps possibility of using:

map[string]struct{

    Name string

    Constructor func() json.Unmarshaler

    OmitEmpty bool

    String bool

    // ...

}

That would be the ideal thing. But is it possible to do so with current builtin tools? Or some package?

Other notes:

I've found gabs but it does not what I want. Some of my specific cases are big int64 values which should serialized as string because they get converted to ugly float things and some custom parsing for specific strings.

[Egon]

What is the JSON input that you need to parse?

+ Egon

[Egon]

On Tuesday, 4 April 2017 13:54:34 UTC+3, dc0d wrote:

Target: Assuming we want to deserialize some JSON dynamically and we want to unmarshal some fields using specific unmarshaling code (a certain UnmarshalJSON). The problem is using something like map[string]interface{} there is no way to specify that.

Thought Experiment: I like to have something like:

ourUnmarshaler.AddField("name", func() json.Unmarshaler /* default field creator for unmarshaling */, /* other options like omitempty */)

or perhaps possibility of using:

map[string]struct{

    Name string

    Constructor func() json.Unmarshaler

    OmitEmpty bool

    String bool

    // ...

}

That would be the ideal thing. But is it possible to do so with current builtin tools? Or some package?

https://play.golang.org/p/EP2F-__URO

If you need the field names to construct the data, do a separate pass over the data.

[Egon]

On Tuesday, 4 April 2017 15:33:19 UTC+3, Egon wrote:

On Tuesday, 4 April 2017 13:54:34 UTC+3, dc0d wrote:

Target: Assuming we want to deserialize some JSON dynamically and we want to unmarshal some fields using specific unmarshaling code (a certain UnmarshalJSON). The problem is using something like map[string]interface{} there is no way to specify that.

Thought Experiment: I like to have something like:

ourUnmarshaler.AddField("name", func() json.Unmarshaler /* default field creator for unmarshaling */, /* other options like omitempty */)

or perhaps possibility of using:

map[string]struct{

    Name string

    Constructor func() json.Unmarshaler

    OmitEmpty bool

    String bool

    // ...

}

That would be the ideal thing. But is it possible to do so with current builtin tools? Or some package?

https://play.golang.org/p/EP2F-__URO

If you need the field names to construct the data, do a separate pass over the data.

Also you can now use the Decoder as a tokenizer https://golang.org/pkg/encoding/json/#Decoder.Token, so implementing custom unmarshaling isn't that difficult.

[dc0d]

I do not know what's the JSON! I just know it contains some certain fields, somewhere inside - some date-times, geo info (string formatted) and the like. Now parsing these data needs certain unmarshalers. But I know the name of those fields - not their position (they are not necessarily a direct field of the JSON, but maybe a field of a child JSON object).

Token seems interesting! I'll look into it.