noniljson

NonNilJson Linter

The noniljson linter is a static analysis tool for Go that ensures nullable fields in structs used for JSON marshaling include the omitempty option or are handled correctly to avoid marshaling as null in the JSON output. This tool is designed to help Go developers maintain clean and error-free JSON output by enforcing best practices for JSON serialization of Go structures.

Why noniljson?

In Go, when struct fields are marshaled into JSON, fields with nil values are included in the output as null. This behavior can lead to several issues:

• Unexpected null values in JSON output: Consumers of your JSON API may not expect or handle null values correctly, leading to errors or inconsistencies in data processing.
• Data Sparsity: Output JSON might include a lot of null values for optional fields, leading to larger payloads and inefficient data transmission, especially in microservices or APIs where bandwidth and payload size are concerns.
• API Contract Violation: If your API specification defines optional fields should be omitted if not present, including nil values as null in the output violates this contract.

The noniljson linter addresses these issues by enforcing the omitempty option for nullable struct fields. This option ensures that fields with nil values are omitted from the marshaled JSON, resulting in cleaner, more efficient, and spec-compliant JSON output.

By integrating noniljson into your Go projects, you can automatically enforce best practices for JSON serialization across your codebase, improving the quality and reliability of your APIs and data interfaces.

Use Cases

• API Development: Ensuring your JSON endpoints output clean, compliant JSON.
• Microservices: Reducing payload size for efficient inter-service communication.
• Data Storage: Preparing structs for marshaling into JSON databases or files without spurious null values.

In essence, noniljson helps maintain high-quality code standards, ensuring that your Go applications produce optimal JSON output, enhancing compatibility and efficiency in data exchange.

Examples

Consider the following Go struct:

type ExampleStruct struct {
    Name    *string `json:"name"`
    Address string  `json:"address,omitempty"`
}

Running noniljson on this code will report an issue with the Name field for not including the omitempty option, since it's a pointer to a string and thus nullable.