What is GraphQL?

A query language that enables us to do declarative data fetching, which means:

• We can describe the data we want,
• Bundle it all up in one request,
• And get data back in a predictable shape.

Schema:

• Describes the shape of the available data
• A hierarchy of types and fields, populated by backend data stores

Benefits of GraphQL

The journey of a GraphQL operation

(Optional) Follow-along: Our GraphQL API so far

1. Visit our GraphQL API starting point: https://comet-cruises-api.herokuapp.com/

2. Open up a terminal.

   On Mac, you can press Cmd + Space to open up Spotlight. Type "Terminal" and open it up.

3. Paste in the POST request command from the landing page:

   curl --request POST \
    --header 'content-type: application/json' \
    --url 'https://comet-cruises-api.herokuapp.com/' \
    --data '{"query":"query { __typename }"}'

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4. We're getting data back!

   {"data":{"__typename":"Query"}}

5. Let's try querying for locations data. Replace __typename with locations.

   curl --request POST \
    --header 'content-type: application/json' \
    --url 'https://comet-cruises-api.herokuapp.com/' \
    --data '{"query":"query { locations }"}'

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6. We get an error!

   {"errors":[{"message":"Field \"locations\" of type \"[Location!]!\" must have a selection of subfields. Did you mean \"locations { ... }\"?","locations":[{"line":1,"column":9}],"extensions":{"code":"GRAPHQL_VALIDATION_FAILED"}}]}

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   Looks like we need subfields. But this is annoying and I don't know what subfields are available. It's really easy to make typos too!

   There must be a better way 🤔