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Schema linting

Enforce GraphQL formatting conventions and best practices


provides schema linting to help you enforce formatting conventions and other best practices with every proposed change to your graph's schema.

Linter violations in GraphOS Studio
  • If you set up schema checks for your graph, linting runs as a separate check type alongside build and checks.
  • You can also perform one-off linting with the Rover CLI.

NOTE

schema linting only analyzes parts of your modified schema that differ from your published schema. It does not flag any existing violations.

Linter configuration

The schema linter uses a predefined collection of rules to identify issues with proposed schema changes. The predefined collection includes schema composition rules. The graph-wide linter defaults you define apply to all of a particular .

To navigate to your linter configuration:

  1. In GraphOS Studio, go to your 's Checks page.

  2. Click Configuration in the upper right to open the checks configuration page.

  3. From the checks configuration page, open the Linter section:

    Linter configuration page in GraphOS Studio

This page organizes linter options into the following categories:

  • General Linter Configuration provides high-level options, including disabling the linter entirely.
  • Approved @tag names enables you to specify approved values for the name of the @tag . This directive is used most commonly with GraphOS contracts.
    • If you don't use the @tag , you can ignore this category.
    • Using a non-approved value for name raises the TAG_DIRECTIVE_USES_UNKNOWN_NAME violation.
  • Rule Severity Configuration enables you to set the severity level for violations of each rule.

If you view this configuration for a single , each category displays a Use Graph Settings toggle in the upper right. If this toggle is enabled, the uses whatever -wide defaults are set for that category. At this time, the Use Graph Settings toggle is always enabled for all .

Setting severity levels

The Rules Severity Configuration category of your linter configuration displays all predefined rules and the current severity level for each:

Linter configuration page in GraphOS Studio

Click a rule's severity to set it to any of the following:

  • Error. Any violation of this rule causes the associated linter check to fail.
    • This in turn causes the entire run to fail, which is useful for failing builds in CI.
  • Warn. Violations of this rule are flagged in checks reports, but they don't cause the associated linter check to fail.
  • Ignore. Violations of this rule are ignored entirely.

For information on specific rules, see the reference list of rules.

Running the linter

Schema linting runs automatically as part of your 's schema checks. You can also perform one-off linting of local schema changes via the .

Linting via schema checks

If you set up schema checks for your , schema linting automatically runs as a separate check type alongside build and checks. You can view the results of all check types from your graph's Checks page in Studio:

Checks page in Studio showing all check types

💡 TIP

For the best experience running linter checks, install v0.16 or later of the Rover CLI. Earlier versions of can't correctly output the results of linter checks, but they do correctly exit with a nonzero code if a linter check fails.

One-off linting

NOTE

One-off linting requires v0.16 or later of the Rover CLI. Install the latest version.

The provides subgraph lint and graph lint commands for running the linter against your local schema changes.

  • Use subgraph lint for in a .
  • Use graph lint for monographs (not recommended).

The rover subgraph lint and rover graph lint commands validate all linter rules except for composition rules. Use rover subgraph check or rover supergraph compose to validate rules locally.

Example command
rover subgraph lint --name products --schema ./products-schema.graphql my-graph@my-variant

The my-graph@my-variant in the example above is a graph ref that specifies the ID of the you're comparing your schema changes against, along with which variant you're comparing against.

Command options include:

NameDescription
--schema

Required. The path to a local .graphql or .gql file, in SDL format.

Alternatively, you can provide -, in which case the command uses an string piped to stdin instead (see Using stdin).

--name

Required for subgraph lint. Omit for graph lint. The name of the published to compare schema changes against.

--ignore-existing-lint-violations

If provided, the linter only flags violations that are present in the diff between your local schema and your published schema.

By default, one-off linting flags all violations in your local schema.

Linter rules

See this reference list of rules.

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