Icon LinkQueries

Once data has been persisted into your storage backend, you can retrieve it by querying the GraphQL API server. By default, the API server can be reached at http://localhost:29987/api/graph/:namespace/:identifier, where :namespace and :identifier are the values for the respective fields in your indexer's manifest. If you've changed the GRAPHQL_API_HOST or GRAPHQL_API_PORT values of your configuration, then you'll need to adjust the URL accordingly.

Icon LinkBasic Query

A basic query has the following form:

query {
    entity {
        field_1
        field_2
        ...
    }
    ...
}

The entity field corresponds to the name of an entity defined in your schema and the sub-fields are the fields defined on that entity type; entities and fields are stored in the database using the names defined in the schema, so make sure that your query uses those same names as well.

query {
    block {
        id
        height
        timestamp
    }
}

We're requesting the ID, height, and timestamp for each block stored in the backend. If successful, the API server will return a response similar to the following:

[
   {
      "height" : 1,
      "id" : "f169a30cfcbf1eebd97a07b19de98e4b38a4367b03d1819943be41744339d38a",
      "timestamp" : 1668710162
   },
   {
      "height" : 2,
      "id" : "a8c554758f78fe73054405d38099f5ad21a90c05206b5c6137424985c8fd10c7",
      "timestamp" : 1668710163
   },
   {
      "height" : 3,
      "id" : "850ab156ddd9ac9502768f779936710fd3d792e9ea79bc0e4082de96450b5174",
      "timestamp" : 1668710312
   },
   {
      "height" : 4,
      "id" : "19e19807c6988164b916a6877fe049d403d55a07324fa883cb7fa5cdb33438e2",
      "timestamp" : 1668710313
   },
   {
      "height" : 5,
      "id" : "363af43cfd2a6d8af166ee46c15276b24b130fc6a89ce7b3c8737d29d6d0e1bb",
      "timestamp" : 1668710314
   }
]

Icon LinkNested Query

The Fuel indexer supports foreign keys on entity types; thus, you can also ask for information about a referenced entity inside of your query. A nested query has the following general structure:

query {
    entityA {
        field_A1
        field_A2
        referenced_entityB {
            field_B1
            field_B2
            ...
        }
        ...
    }
    ...
}

Essentially, it's the same as the basic query example with an added sub-block to request information about the reference entity. The response from the API server will be returned in the same general structure as the query. Let's look at another example to illustrate how it works in practice.

Important: There is no limit to how deeply nested your entities and queries can be. However, every nested reference will add computation and latency to your query as the information will have to be retrieved from different tables in your storage backend. Please exercise caution in your entity design and try to minimize nesting as much as possible.

We'll start with the following example schema:

type City {
    id: ID!
    name: Charfield!
}
 
type Library {
    id: ID!
    name: Charfield!
    city: City!
}
 
type Book {
    id: ID!
    title: Charfield!
    library: Library!
}
 
type Character {
    id: ID!
    name: Charfield!
    book: Book!
}

This schema uses implicit foreign keys to reference other entities; for more information on implicit and explicit foreign keys, please refer to the Foreign Keys section of the book. In this contrived example, we're storing information about characters that are found in books which are stored in libraries that can be found in cities. This will be the query that we use to retrieve the aforementioned data:

query {
    character {
        name
        book {
            title
            library {
                name
                city {
                    name
                }
            }
        }
    }
}

Let's assume that we've created an indexer for this data and the indexed data has been stored in the database. If we send the query, we'll get the following response:

[
  {
    "name": "Lil Ind X",
    "book": {
      "title": "Fuel Indexer",
      "library": {
        "name": "Fuel Labs Library",
        "city": {
          "name": "Fuel City"
        }
      }
    }
  }
]