Aliases in GraphQL

GraphQL is a powerful open-source query language for APIs. It is known for its flexibility and efficiency in fetching data from server endpoints. Unlike traditional REST APIs, which often have multiple endpoints for different resources, GraphQL typically exposes a single endpoint that allows clients to request exactly the data they need.

Aliases in GraphQL allow the users to rename the various fields in the query to something more descriptive, and contextual, that helps in enhancing the query readability. In this article, we will explore what are aliases in GraphQL.

What are GraphQL Aliases?

GraphQL aliases are a powerful tool that help in assigning alternative names to the fields present in the query. This ultimately allows the user to fetch the data with the different names given to the fields, to make the query more descriptive and easy to read. They can be useful when there are multiple fields present with same or similar name in the schema.

Using Aliases in a Query

Let's understand how aliases work with the help of an example. We will use the below GraphQL API for the sake of this example.

GraphQL API -

https://studio.apollographql.com/public/countries/variant/current/explorer

Example

In the below example, we use the aliases "firstCountry" and "secondCountry" to differentiate between the queries made to the server. We also use the aliases "title", and "bill" to rename the fields "name" and "currency" we initially get from the API, so as make the final query output more readable and succint.

query {
  firstCountry: country(code: "BR") {
    title: name
    bill: currency
  }
  secondCountry: country(code: "IN") {
    title: name
    bill: currency
  }
}

Output:

Fetching multiple objects in one query

Aliases are especially useful when we want to fetch multiple objects having the same types in a single query. Without aliases, the objects having the same types or interfaces will have some data keys that conflict with each other, but aliases solves the problem by renaming those as per the users' requirements.

Example

In this example, we will use the above GraphQL server to query the results. We will fetch different country objects from the server, and use aliases to differentiate among them in the output.

query {
  usa: country(code: "US") {
    name
  }
  uk: country(code: "GB") {
    name
  }
  germany: country(code: "DE") {
    name
  }
}

Output:

Using aliases to avoid name clashes

When two or more fields in a GraphQL schema have the same name, then the conflicts will happen while fetching the data from the server. With aliases, we can allow unique names to the conflicting fields to avoid any confusion in the response data.

Example

In this example, we will use aliases, country1 and country2 to differentiate between the 2 country objects. And we will use countryName to avoid any confusion on conflict from the other country's output data.

query {
  country1: country(code: "US") {
    countryName: name
  }
  country2: country(code: "GB") {
    countryName: name
  }
}

Output:

Using aliases to fix singularization rules

GraphQL's convention of following the singularization principle while naming entities can be easily solved by aliases by assigning different names to output data's entity.

Example:

In this example, we will fetch information about multiple countries, and we will use allCountries alias to pluralize the response data.

query {
  allCountries: countries {
    name
  }
}

Output:

Conclusion

In this article, we learnt about the GraphQL aliases, and we also saw an example explaining the same. With the help of aliases, we can easily enhance the query flexibility and readability, and make the query output consistent with the naming conventions. By giving alternate names to the query fields, we can make the end query response more contextual and succint.