dd_04_io

dd_04_io - JSON, YAML, and JSONL i/o

this example demonstrates the layered dd i/o api: binding and unbinding JSON and YAML from bytes, readers/writers, and files, plus appending records to a JSON Lines stream.

key concepts demonstrated

three layers, one shape

• bytes: dd.BindJSON/dd.BindYAML and dd.UnbindJSON/dd.UnbindYAML
• readers and writers: dd.BindJSONReader/dd.BindYAMLReader and dd.UnbindJSONWriter/dd.UnbindYAMLWriter
• files: dd.BindJSONFile/dd.BindYAMLFile and dd.UnbindJSONFile/dd.UnbindYAMLFile (dd.NewJSONFile[T]/dd.NewYAMLFile[T] allocate the target for you)

json lines

• dd.UnbindJSONLWriter: one compact, newline-terminated record per call, appended to any io.Writer — open the file with O_APPEND and call it once per record
• reading back: nothing new — bufio.Scanner plus dd.BindJSON per line

error handling

• consistent dd error types across every layer: file errors, parse errors, and binding errors

workflow demonstrated

1. bytes layer: bind from JSON/YAML bytes, unbind back to bytes
2. reader/writer layer: the same through io.Reader and io.Writer
3. file layer: write config.json and config.yaml, read them back
4. jsonl record streams: append three records to events.jsonl, scan them back
5. format conversion: bind JSON, unbind YAML
6. error handling: missing file, invalid JSON, invalid YAML

file structure

the example creates, reads, and removes these files in the working directory:

config.json     - JSON configuration file
config.yaml     - YAML configuration file
events.jsonl    - JSON Lines record stream

usage

go run main.go

benefits

• one api, three layers: bytes, readers/writers, and files share the same shape and options
• consistent error handling: unified error types for file, parse, and binding failures
• format agnostic: the same struct definitions work with JSON, YAML, and JSONL
• streamable: JSONL records append to logs and exports without buffering a whole document