drop_matching

Removes top-level fields from a record when their names match a regular expression.

drop_matching(x:record, regex:string) -> record

Description

The drop_matching function returns a record with every top-level field from x whose field name does not match regex.

Matching is partial by default. Use ^ and $ anchors to match whole field names or prefixes. The function does not recurse into nested records; call it on the nested record if you want to drop fields there.

The supported regular expression syntax is RE2.

`x: record`

The record whose fields you want to filter.

`regex: string`

The regular expression to match against field names.

Examples

Remove fields by name

from {
  name: "Alice",
  email: "alice@example.com",
  password: "secret",
  api_key: "xyz123",
}
select public = this.drop_matching("^(password|api_key)$")

{
  public: {
    name: "Alice",
    email: "alice@example.com",
  },
}

Separate matching fields from the rest

from {
  foo: 1,
  bar: 2,
  baz: 3,
}
let $pattern = "^ba"
select moved = this.select_matching($pattern),
       rest = this.drop_matching($pattern)

{
  moved: {
    bar: 2,
    baz: 3,
  },
  rest: {
    foo: 1,
  },
}