Filters

Learn how to run a subset of the rules a configuration enables.

--filter takes an expression over the rules the configuration loaded, and runs only the ones it selects:

vale --filter='.Level == "error"' docs/

A filter narrows a run and never widens it: a rule the configuration did not enable is not there to select. Everything else about the run stays as configured, with one exception. When the expression mentions .Level, the minimum alert level drops to include what it selected, so --filter='.Level == "suggestion"' shows suggestions even under MinAlertLevel = warning.

Using --filter to limit results to alerts whose scope is a heading.

The expression

A filter is an expression, evaluated once per rule against the rule's header. The fields are the ones every rule opens with, capitalized:

Field	Type	Example
.Name	string	.Name == "Microsoft.Contractions"
.Level	string	.Level in ["error", "warning"]
.Scope	string[]	"heading" in .Scope
.Extends	string	.Extends == "spelling"
.Message	string	.Message contains "instead"
.Description	string	.Description != ""
.Link	string	.Link startsWith "https://developers."

.Scope is a list because a rule may name several, so membership is the test. Expressions combine with and, or, and not, and the operators include matches for a regular expression:

# Every rule from one style, at any level.
vale --filter='.Name startsWith "Google."' docs/

# Only spelling, and only in headings.
vale --filter='.Extends == "spelling" and "heading" in .Scope' docs/

# Everything except one rule.
vale --filter='.Name != "Vale.Spelling"' docs/

Saving a filter

A filter that is typed twice belongs in a file. --filter accepts a path, or the name of a file in the StylesPath's config/filters directory:

vale --filter=headings.expr docs/

# config/filters/headings.expr
"heading" in .Scope

The value is tried as a path first, then as a name on the StylesPath, and read as an expression only when it is neither, so a file that is not where it was expected is reported as a bad expression rather than silently run as one.