How to Handle Dynamic JSON Keys During Unmarshaling in Go?

Dynamic Key Handling in JSON Unmarshaling: GoLang

In GoLang, unmarshaling JSON data into a struct can become challenging when the keys in the JSON are dynamic or cannot be directly mapped to a specific field in the struct. This article presents a solution to this issue by introducing the use of a map to capture dynamic keys and their associated values.

Problem Description:

Consider the following struct:

type X struct {
 A string `json:"a_known_string"`
 B string `json:"b_known_string"`
}

and a JSON string:

"{
 "any string" : {
   "a_known_string" : "some value",
   "b_known_string" : "another value" 
 }
}"

Using the standard JSON Unmarshal function with the struct would not capture the dynamic key, "any string".

Solution Using a Map:

To solve this issue, we can use a map to store the dynamic key-value pairs. Here's an example:

var m map[string]X
err := json.Unmarshal([]byte(jsnStr), &m)

In this solution, the m variable will be a map where the keys are the dynamic strings, and the values are instances of the X struct.

This approach allows us to capture the dynamic keys and their corresponding values while still maintaining a structured representation of the data.

Playground Example:

The provided playground example demonstrates the use of the solution:

https://go.dev/play/p/tZ27zKhI9Ct

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