Templating

A value may reference other keys with ${...} placeholders. References are resolved recursively while the object is built, so derived values stay in one place instead of being duplicated across rows.

// rows:
//   environment.host          = 'device.local'
//   device.diagnostics.upload = 'https://${environment.host}/upload'

cfg.get('device.diagnostics.upload'); // 'https://device.local/upload'

A placeholder can point at another templated value; Configuard follows the chain until it reaches a concrete value.

// port               = '8080'
// environment.intPort = '${port}'   →  8080

Missing References Throw

If a ${...} reference points at a key that doesn’t exist, construction throws:

ConfiguardError: Referenced value for template is missing: "${missing.key}"

Circular References Are Detected

A cycle (a → ${b}, b → ${a}) would otherwise recurse forever. Configuard tracks the keys being resolved and throws instead:

ConfiguardError: Circular template reference detected at: "a"

A Note on Access-Filtered References

A template is only as resolvable as the rows visible to the current accessor. If a value references a key the client can’t see (a higher-privilege accessor), that reference resolves to undefined — e.g. "${google.email}@gmail.com" becomes "[email protected]". Keep templated values within the same access tier as their references.

Note

Templating also runs in parseFlat(), where the resolved value is kept as a string rather than cast to its type — the same missing/circular checks apply.