Using composable directives

Have a directive modify the behavior of another directive.

This functionality allows to be able to use a directive, when otherwise we could not use it due to a type mismatch (i.e. when a directive cannot be applied on the field, because it has an input which is different than the field's output).

For instance, field capabilities returns [String] (an array of strings), and directive @strUpperCase receives String. Hence, executing the following query returns an error due to the type mismatch:

query {
  user(by: {id: 1}) {
    capabilities @strUpperCase
  }
}Copy

With composable directives, we can employ directive @underEachArrayItem (which iterates over an array of elements, and applies its nested directive on each of them) to set the stage before @strUpperCase is executed, making it receive a single element (of type String).

The query from above can be satisfied like this:

query {
  user(by: {id: 1}) {
    capabilities
      @underEachArrayItem
        @strUpperCase
  }
}Copy

​

Meta directives

Every meta directive can affect (or "nest") multiple directives at once. Which directives are affected is indicated via argument affectDirectivesUnderPos, which receives an array of positive integers, each of them defining the affected directive's relative position.

By default, argument affectDirectivesUnderPos has default value [1], meaning that it will affect the directive right next to it.

In the example below, we have:

• @underEachArrayItem is the meta directive
• @strTranslate is nested under @underEachArrayItem (implicit default value affectDirectivesUnderPos: [1])

{
  someField
    @underEachArrayItem
      @strTranslate
}Copy

In the example below, we instead have:

• @strTranslate and @strUpperCase are nested under @underEachArrayItem (as indicated by relative positions [1, 2] in argument affectDirectivesUnderPos)

{
  someField
    @underEachArrayItem(affectDirectivesUnderPos: [1, 2])
      @strTranslate
      @strUpperCase
}Copy

Meta directives can also be nested within meta directives.

In the example below, we have:

• @underEachArrayItem is the topmost meta directive
• @underJSONObjectProperty is nested under @underEachArrayItem
• @strUpperCase is nested under @underJSONObjectProperty

query UppercaseEntriesInsideObject {
  entries: _echo(value: [
    {
      text: "Hello my friends"
    },
    {
      text: "How do you like this software so far?"
    }
  ])
   @underEachArrayItem
      @underJSONObjectProperty(by: { key: "text" })
        @strUpperCase
  }Copy

​

Configuration

To enable or disable composable directives in the GraphQL schema, go to the "Composable Directives" module on the Settings page, and tick/untick the checkbox for Enable composable directives?:

To enable or disable composable directives on a specific endpoint, select the desired option in block "Composable Directives" from the corresponding Schema Configuration: