How to Unmarshal Dynamic JSON Structures with Type Keys in Go?

Unmarshaling Dynamic JSON Structures with Type Key

In situations where JSON documents contain heterogeneous structures with dynamically typed fields, it becomes necessary to devise a strategy for efficient unmarshaling into Go structs. A common requirement is to unmarshal JSON documents into a struct without introducing additional generic fields as placeholders for variant fields.

To achieve this, one approach is to create an interface that represents the common properties among the variant fields. In this case, a Something interface with a GetType() method can be defined. Additionally, several structs and functions can be constructed to support different types of dynamic fields with different properties, such as DynamicTypeA and DynamicTypeB.

The next step involves implementing a json.Unmarshaler for the BigStruct type. This custom unmarshaling method can inspect the Type field within the dynamic_field JSON object and dynamically determine the type of DynamicField field. For example, if the Type field is "A," the DynamicField field should be set to an instance of DynamicTypeA. This allows for runtime type selection based on the JSON structure.

An alternative approach, if the type of the DynamicField cannot be changed, is to implement the UnmarshalJSON method on the BigStruct type and declare a temporary type to avoid recursion. This temporary type serves as an intermediary for the unmarshaling process, preventing infinite recursion.

By embracing these techniques, it is possible to effectively unmarshal dynamic JSON structures into Go structs, enabling the flexible handling and manipulation of variant field types.

The above is the detailed content of How to Unmarshal Dynamic JSON Structures with Type Keys in Go?. For more information, please follow other related articles on the PHP Chinese website!