GraphQL in Blockscout

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GraphQL in Blockscout

Blockscout provides GraphQL API to easily fetch data from Blockscout.

What is GraphQL

GraphQL is an open-source data query and manipulation language for APIs, and a runtime for fulfilling queries with existing data. It provides an efficient, powerful and flexible approach to developing web APIs… It allows clients to define the structure of the data required, and exactly the same structure of the data is returned from the server, therefore preventing excessively large amounts of data from being returned.

Key concepts of the GraphQL query language are:

  • Hierarchical
  • Strongly typed
  • Client-specified queries

Advantages of GraphQL:

  • Declarative integration on client (what data/operations do I need)
  • A standard way to expose data and operations
  • Support for real-time data (with subscriptions)

Query types

There are three main query types in GraphQL schema:

  1. Query - a way to fetch data.

    query {
      allPosts {
        description
        text
      }
    }
    
  2. Mutation - a way to change data.

    mutation {
      updatePost(id: 1, text: "text") {
        text
      }
    }
    
  3. Subscription - a way to subscribe to real-time data.

    subscription {
      newPost(category: [1]) {
        description
        text
      }
    }
    

Blockscout

How to access GraphQL API

To access Blockscout GraphQL interface you can you can use GraphiQL - in-browser IDE for exploring GraphQL. It’s builtin in Blockscout.

From the APIs dropdown menu choose GraphQL.

Or you can use your favourite http client:

curl 'https://blockscout.com/eth/kovan/graphiql'
  -H 'Authorization: Bearer YOUR_AUTH_TOKEN'
  -d '{"query":""{transaction(hash:\"0x69e3923eef50eada197c3336d546936d0c994211492c9f947a24c02827568f9f\"){blockNumbertoAddressHashfromAddressHashcreatedContractAddressHashvaluestatusnoncehasherrorgasgasPricegasUsedcumulativeGasUsedidindexinputrsv}}""}'
Queries

Blockscout’s GraphQL API provides 4 queries and 1 subscription. You can view them in GraphiQL interface under Schema tab. Let’s give a short examples of some of these queries.

Query Description Example
address(hash: AddressHash!): Address Gets an address by hash {address(hash: “0x1fddEc96688e0538A316C64dcFd211c491ECf0d8”) {hash, contractCode} }
addresses (hashes: [AddressHash!]): [Address] Gets addresses by hashes {addresses(hashes: [“0x1fddEc96688e0538A316C64dcFd211c491ECf0d8”, “0x3948c17c0f45017064858b8352580267a85a762c”]) {hash, contractCode} }
block(number: Int!): Block Gets a block by number {block(number: 1) {parentHash, size, nonce}}
transaction (hash: FullHash!): Transaction Gets a transaction by hash. {transaction(hash: “0xc391da8f433b3bea0b3eb45da40fdd194c7a0e07d1b5ad656bf98940f80a6cf6”) {input, gasUsed}}