Go package¶

import "github.com/enerplanet/T1K/pkg/t1k"

API reference: pkg.go.dev/github.com/enerplanet/T1K/pkg/t1k.

Transforming¶

task := t1k.NewTransformTask()
job, err := task.Transform(payload)   // []byte in, []byte out
back, err := task.Reverse(job)

Transform applies the configuration in the forward direction, Reverse in the reverse direction. Both take a JSON document as a byte slice and return one; the output is compact unless WithIndent is set.

A TransformTask binds a configuration and the output format. It holds no per-call state: every call decodes its input, runs on a fresh output document and encodes the result, so one task may be used from several goroutines at once. Creating one task per conversion job, the intended pattern, is cheap: a task is a pointer to a shared, immutable configuration and two formatting options.

Configurations¶

Function	Purpose
`DefaultConfig()`	the embedded mapping (`config/enerplanet-to-meme.json`, shipped through the `config` package), parsed once when the package initialises
`DefaultConfigJSON()`	a copy of its JSON text, for example to write out as the starting point of a custom mapping
`LoadConfig(data []byte)`	parse and validate a configuration from its JSON text
`LoadConfigFile(path string)`	the same from a file; the error names the file

A Config is immutable after loading and safe to share between tasks. Its exported fields Name, Version and Description carry the metadata from the file, and Rules() returns the number of top-level rules, for diagnostics.

cfg, err := t1k.LoadConfigFile("orders.json")
if err != nil {
    return err // wraps t1k.ErrConfig; the message names the offending rule
}
task := t1k.NewTransformTask(t1k.WithConfig(cfg), t1k.WithIndent("", "  "))

Options¶

Option	Effect
`WithConfig(cfg)`	use `cfg` instead of the default; `nil` keeps the default
`WithIndent(prefix, indent)`	indented output, as `json.MarshalIndent` would produce; empty strings restore compact output

Errors¶

Every error the package returns wraps one of three sentinels, so callers can classify failures with errors.Is:

Sentinel	When
`ErrConfig`	the configuration failed to parse or validate, or its file could not be read; the message names the rule and the field
`ErrInput`	the document is not valid JSON, or has content after the first document
`ErrRule`	a rule could not be applied: a converter received a value it cannot handle, a `match` guard failed, a `bind` path is missing from an element, or a variable bound to text is used as an array index; the message names the rule and the direction

out, err := task.Transform(in)
switch {
case errors.Is(err, t1k.ErrInput):
    // reject the request: the body is not JSON
case errors.Is(err, t1k.ErrRule):
    // the document does not fit the mapping; the message names the rule
}

Working with decoded values¶

The package works on JSON text. If a program already holds a decoded value, marshal it first; if it needs the result as a value, unmarshal the output. This keeps the contract small and the number handling explicit: T1K preserves the digits of every number it only moves (1.0 stays 1.0), which a round trip through float64 would not.