Configuration

DCM is designed to be flexible and configurable for your use case. You can enable metrics or rules individually, or have both metrics and rules enabled.

To configure DCM, add a dcm entry to analysis_options.yaml:

analysis_options.yaml

dcm:
  exclude-public-api: # configures the "exclude-public-api" mode for the commands that use it
  extends:
    - ... # configures the list of preset configurations
  exclude:
    all:
      - ... # configures the list of files that should be ignored by supported excludes
    rules:
      - ... # configures the list of files that should be ignored by rules
    metrics:
      - ... # configures the list of files that should be ignored by metrics
    unused-code:
      - ... # configures the list of files that should be ignored by check-unused-code
    unused-files:
      - ... # configures the list of files that should be ignored by check-unused-files
    parameters:
      - ... # configures the list of files that should be ignored by check-parameters
    dependencies:
      - ... # configures the list of files that should be ignored by check-dependencies
    code-duplication:
      - ... # configures the list of files that should be ignored by check-code-duplication
    unnecessarily-public-code:
      - ... # configures the list of files that should be ignored by check-unnecessarily-public-code
    unnecessarily-mutable-fields:
      - ... # configures the list of files that should be ignored by check-unnecessarily-mutable-fields
    exports:
      - ... # configures the list of files that should be ignored by check-exports-completeness
  formatter:
    - ... # configures the formatter
  metrics:
    - ... # configures the list of reported metrics
  pubspec-rules:
    - ... # configures the list of rules for pubspec.yaml
  rules:
    - ... # configures the list of rules
  project: # configures the project id for DCM Dashboards (Enterprise only)
  project-tags:
    - ... # configure the list of tags for DCM Dashboards (Enterprise only)

note

This configuration is used by both CLI and the IDE analyzer.

Basic config example:

analysis_options.yaml

dcm:
  rules:
    - avoid-dynamic
    - avoid-passing-async-when-sync-expected
    - avoid-redundant-async
    - avoid-unnecessary-type-assertions
    - avoid-unnecessary-type-casts
    - avoid-unrelated-type-assertions
    - avoid-unused-parameters
    - avoid-nested-conditional-expressions
    - newline-before-return
    - no-boolean-literal-compare
    - no-empty-block
    - prefer-trailing-comma
    - prefer-conditional-expressions
    - no-equal-then-else
    - prefer-moving-to-variable
    - prefer-match-file-name
    - avoid-collapsible-if
    - avoid-redundant-else
    - avoid-incomplete-copy-with
    - avoid-self-compare
    - avoid-self-assignment
    - avoid-unnecessary-nullable-return-type
    - avoid-unrelated-type-casts
    - prefer-declaring-const-constructor

info

You can find a list of recommended rules here.

Basic config with metrics:

analysis_options.yaml

dcm:
  metrics:
    cyclomatic-complexity:
      threshold: 20
    number-of-parameters:
      threshold: 4
    maximum-nesting-level:
      threshold: 5
  exclude:
    metrics:
      - test/**
  rules:
    - avoid-dynamic
    - avoid-passing-async-when-sync-expected
    - avoid-redundant-async
    - avoid-unnecessary-type-assertions
    - avoid-unnecessary-type-casts
    - avoid-unrelated-type-assertions
    - avoid-unused-parameters
    - avoid-nested-conditional-expressions
    - newline-before-return
    - no-boolean-literal-compare
    - no-empty-block
    - prefer-trailing-comma
    - prefer-conditional-expressions
    - no-equal-then-else
    - prefer-moving-to-variable
    - prefer-match-file-name
    - avoid-collapsible-if
    - avoid-redundant-else
    - avoid-incomplete-copy-with
    - avoid-self-compare
    - avoid-self-assignment
    - avoid-unnecessary-nullable-return-type
    - avoid-unrelated-type-casts
    - prefer-declaring-const-constructor

info

You can find a list of recommended metrics here.

Configuration-related Issues

Ignore Issues

Ignore issues are synthetic issues produced by the analyzer when parsing ignore comments (// ignore: and // ignore_for_file: ). Such issues do not have corresponding rules and cannot be ignored or enabled/disabled.

Issue name	Description
avoid-duplicate-ignores	Highlights ignores that appear more than once.
avoid-unused-ignores	Highlights ignores that have no effect.

Configuration Issues

Configuration issues are synthetic issues produces by the analyzer when parsing the analysis_options.yaml file. Such issues do not have corresponding rules and cannot be ignored or enabled/disabled.

Issue name	Description
duplicate-rule	Highlights a rule that is added to the list of rules more than one time.
unknown-rule	Highlights a rule that does not match any known rule name.
not-available-rule	Highlights a rule that is not available to your pricing plan.
config-not-available	Highlights a rule configuration that is not available to your pricing plan.
empty-rule-config	Highlights a rule with an incorrect configuration resulting in an empty configuration.
unknown-rule-config	Highlights a rule that has an unknown configuration entry.
incorrect-rule-config	Highlights a rule that has an incorrect configuration entry.
requires-config	Highlights a rule that requires configuration to show any issues.
unknown-metric	Highlights a metric that does not match any known metric name.
empty-metric-config	Highlights a metric with an incorrect configuration resulting in an empty configuration.
unknown-metric-config	Highlights a metric that has an unknown configuration entry.
incorrect-metric-threshold	Highlights a metric that has an incorrect threshold value.
incorrect-metric-config	Highlights a metric that has an incorrect configuration entry.
preset-not-found	Highlights an unresolved or incorrect preset name.
incorrect-preset-config	Highlights an incorrectly configured preset.
presets-not-available	Highlights a preset that is not available to your pricing plan.
incorrect-exclude-public-api-config	Highlights an incorrectly configured exclude-public-api entry.
incorrect-exclude-config	Highlights an incorrectly configured exclude entry.
unknown-exclude-config	Highlights an incorrectly configured exclude subentry.
unknown-config	Highlights an unknown top-level config entry.

Custom analysis_option.yaml Files

Aside from the regular analysis_option.yaml file, you can add a custom config file that matches one of the given patterns

• starts with analysis_options (e.g. analysis_options.1.1.0.yaml)
• starts with dcm (e.g. dcm_config.yaml or dcm.yaml)
• placed inside a folder called dcm (e.g. dcm/config.yaml)

If such a file is referenced by any analysis_option.yaml file, DCM will correctly update configuration changes, validate rule names and display a configuration icon (⚙️) for configurable rules.

However, unlike for regular analysis_options.yaml files, code actions are not available.

IDE autocompletion

VS Code

To enable configuration autocompletion, modify the settings.json to the following:

.vscode/settings.json

{
  "[yaml]": {
    "editor.quickSuggestions": {
      "strings": "on"
    }
  }
}

IntelliJ / Android Studio

No additional configuration is needed, simply modify any analysis_options.yaml file with DCM configuration to see the autocompletion results.

Excluding Public API

For commands that can affect the package's public API ("Check Unused Code", "Check Unused Files" and "Check Parameters"), setting the exclude-public-api entry in the analysis_options.yaml file will override the --exclude-public-api CLI option.

For example, if publicly exported files of a particular package are not expected to be changed, setting the exclude-public-api entry to true and running the command will exclude the public API only for that particular package.

analysis_options.yaml

dcm:
  exclude-public-api: true # excludes public API for a particular package

Next Steps

• Configure Rules
• Configure Metrics
• Use a Preset
• Exclude Code from Analysis
• Configure Formatter