BitLogger/docs/api/redact-fields.md

name, group, category, update-time, description, key-word

name	group	category	update-time	description	key-word
redact-fields	api	patching	20260512	Create a reusable record patch that redacts multiple field keys.	patch redact fields public

Redact-fields

Create a RecordPatch that replaces the value of every field whose key appears in a provided key list. Use it for shared masking rules across several sensitive fields.

Interface

pub fn redact_fields(keys : Array[String], placeholder~ : String = "***") -> RecordPatch {}

input

• keys : Array[String] - Field keys whose values should be redacted.
• placeholder : String - Replacement value written into each matching field.

output

• RecordPatch - Patch that returns a record with matching field values redacted.

Explanation

Detailed rules explaining key parameters and behaviors

• The patch maps over the record field list and rewrites any field whose key is contained in keys.
• Non-matching fields are preserved.
• The same placeholder is applied to every matching key in the set.
• This helper is useful for masking bundles such as token, password, and secret with one patch.

How to Use

Here are some specific examples provided.

When Mask Several Sensitive Keys

When one logger must protect multiple credentials:

let logger = Logger::new(console_sink())
  .with_patch(redact_fields(["token", "password", "secret"]))

In this example, every matching field value is masked before the sink sees it.

When Share One Custom Mask

When the output should show one explicit policy marker:

let patch = redact_fields([
  "access_key",
  "session_key",
], placeholder="[hidden]")

In this example, all matching fields use the same replacement text.

Error Case

e.g.:

• If keys is empty, the patch behaves like a pass-through field mapper.

• If the same key appears multiple times in keys, matching behavior is unchanged because membership is what matters.

Notes

1. This helper is better than stacking many single-key patches when all keys share the same placeholder policy.

2. It only rewrites structured fields, not text inside the message body.