github.com/codysnider/go-ethereum@v1.10.18-0.20220420071915-14f4ae99222a/graphql/service.go (about)

     1  // Copyright 2019 The go-ethereum Authors
     2  // This file is part of the go-ethereum library.
     3  //
     4  // The go-ethereum library is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU Lesser General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // The go-ethereum library is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU Lesser General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU Lesser General Public License
    15  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package graphql
    18  
    19  import (
    20  	"encoding/json"
    21  	"net/http"
    22  
    23  	"github.com/ethereum/go-ethereum/internal/ethapi"
    24  	"github.com/ethereum/go-ethereum/node"
    25  	"github.com/graph-gophers/graphql-go"
    26  )
    27  
    28  type handler struct {
    29  	Schema *graphql.Schema
    30  }
    31  
    32  func (h handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
    33  	var params struct {
    34  		Query         string                 `json:"query"`
    35  		OperationName string                 `json:"operationName"`
    36  		Variables     map[string]interface{} `json:"variables"`
    37  	}
    38  	if err := json.NewDecoder(r.Body).Decode(&params); err != nil {
    39  		http.Error(w, err.Error(), http.StatusBadRequest)
    40  		return
    41  	}
    42  
    43  	response := h.Schema.Exec(r.Context(), params.Query, params.OperationName, params.Variables)
    44  	responseJSON, err := json.Marshal(response)
    45  	if err != nil {
    46  		http.Error(w, err.Error(), http.StatusInternalServerError)
    47  		return
    48  	}
    49  	if len(response.Errors) > 0 {
    50  		w.WriteHeader(http.StatusBadRequest)
    51  	}
    52  
    53  	w.Header().Set("Content-Type", "application/json")
    54  	w.Write(responseJSON)
    55  
    56  }
    57  
    58  // New constructs a new GraphQL service instance.
    59  func New(stack *node.Node, backend ethapi.Backend, cors, vhosts []string) error {
    60  	if backend == nil {
    61  		panic("missing backend")
    62  	}
    63  	// check if http server with given endpoint exists and enable graphQL on it
    64  	return newHandler(stack, backend, cors, vhosts)
    65  }
    66  
    67  // newHandler returns a new `http.Handler` that will answer GraphQL queries.
    68  // It additionally exports an interactive query browser on the / endpoint.
    69  func newHandler(stack *node.Node, backend ethapi.Backend, cors, vhosts []string) error {
    70  	q := Resolver{backend}
    71  
    72  	s, err := graphql.ParseSchema(schema, &q)
    73  	if err != nil {
    74  		return err
    75  	}
    76  	h := handler{Schema: s}
    77  	handler := node.NewHTTPHandlerStack(h, cors, vhosts, nil)
    78  
    79  	stack.RegisterHandler("GraphQL UI", "/graphql/ui", GraphiQL{})
    80  	stack.RegisterHandler("GraphQL", "/graphql", handler)
    81  	stack.RegisterHandler("GraphQL", "/graphql/", handler)
    82  
    83  	return nil
    84  }