How to Properly Read and Parse JSON Files in Go?

Reading JSON Files as JSON Objects in Go

While attempting to read a JSON file into a variable, subsequent attempts to loop through it and retrieve JSON object values can lead to problematic outcomes. The initial attempt using the Marshal command yields numeric output, while a subsequent attempt to store JSON values in a struct and use MarshalIndent results in a string output.

For success, an interface value being populated by json.Unmarshal must be a pointer. The correct approach is as follows:

plan, _ := ioutil.ReadFile(filename)
var data interface{}
err := json.Unmarshal(plan, &data)

The error "Unmarshal(nil)" observed in the initial attempt indicates a problem with file reading. Checking the error returned by ioutil.ReadFile is crucial.

Furthermore, using an empty interface in unmarshal requires type assertion to access underlying values as Go primitive types. A superior approach involves defining a concrete structure for use with json.Unmarshal.

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