Mapping Enums

When working with REST APIs, you often encounter string values representing states, statuses, or categories that should be represented as enums in your GraphQL schema. Apollo Connectors provides tools for normalizing these values to match your GraphQL enum types, ensuring consistency and type safety.

Common use cases

Enum mapping is particularly valuable in these scenarios:

• Converting lowercase or mixed-case status values (for example, "active" and "Active") to uppercase GraphQL enums (for example, ACTIVE)

• Standardizing variations of the same value (for example, "in_progress", "in progress", and "inProgress") to a single enum value

• Transforming numeric codes (for example, 1, 2, 3) into semantic enum values (for example, PENDING, APPROVED, REJECTED)

• Handling internationalized or legacy values by mapping them to a consistent set of enums

Matching enum values

The example below uses the ->match method to transform status values from active to ACTIVE and not active to INACTIVE.

status: status->match(
  ["active", "ACTIVE"],
  ["not active", "INACTIVE"],
  [@, "UNKNOWN"] # fallback — the value always matches `@`
)

Using the above transformation on the following response data yields the following results:

{
  "status": "active"
}

{
  "status": "ACTIVE"
}

{
  "status": "none of the above"
}

{
  "status": "UNKNOWN"
}

If a match isn't found, the result will be omitted and the field will be null if nullable or result in a validation error if non-nullable. If you want to avoid this, you can use the @ variable to provide a fallback, as shown in the example above.

Mapping arrays of string values

When mapping arrays of strings to lists of enum values, you can use the ->map() method combined with ->match():

1categories: categories->map({
2  @->match(
3    ["fashion", "FASHION"],
4    ["electronics", "ELECTRONICS"],
5    ["home", "HOME"],
6    [@, "OTHER"]
7  )
8})

This transforms an array like ["fashion", "home", "unknown"] into ["FASHION", "HOME", "OTHER"].

Additional resources

• Learn more about GraphQL enum types in the official GraphQL documentation

• Explore other transformation methods in the methods reference