How to write a custom unmarshaller for AWS ION?

php editor Xigua will introduce you how to write a custom parser for AWS ION. AWS ION is an open source data format for processing large-scale data with efficient storage and transfer capabilities. Custom parsers are developed to meet specific needs and are able to convert ION data into specific formats. Writing a custom parser requires understanding ION's data structure and parsing rules, as well as mastering related programming techniques. This article will introduce in detail how to write a custom parser and provide practical cases for reference. Whether you are a beginner or an experienced developer, you can get help and guidance.

Question content

I am using amazon ion to marshal and demarshal data received from various aws services.

I need to write a custom unmarshalling function, I found an example of how to implement this in the official documentation of amazon ion, see here

Using the example above, I wrote the following code:

package main

import (
    "bytes"
    "fmt"

    "github.com/amzn/ion-go/ion"
)

func main() {
    UnmarshalCustomMarshaler()
}

type unmarshalMe struct {
    Name   string
    custom bool
}

func (u *unmarshalMe) UnmarshalIon(r ion.Reader) error {
    fmt.Print("UnmarshalIon called")
    u.custom = true
    return nil
}

func UnmarshalCustomMarshaler() {
    ionBinary, err := ion.MarshalBinary(unmarshalMe{
        Name: "John Doe",
    })
    if err != nil {
        fmt.Println("Error marshalling ion binary: ", err)
        panic(err)
    }

    dec := ion.NewReader(bytes.NewReader(ionBinary))
    var decodedResult unmarshalMe

    ion.UnmarshalFrom(dec, &decodedResult)
    fmt.Println("Decoded result: ", decodedResult)
}

Problem: The above code does not work as expected. The unmarshalion function is not called, but according to the documentation it should be. What did i do wrong?

Workaround

You may be using v1.1.3, which does not include this feature by default.

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