examples: adds crud example

Author: Maksim Chagin

examples/crud/Readme.md

@@ -0,0 +1,25 @@
+# Go GraphQL CRUD example
+
+Implementation create, read, update and delete on Go    
+
+To run the program, go to the directory    
+`cd examples/crud`
+
+Run the example    
+`go run main.go`
+
+## Create
+`http://localhost:8080/product?query=mutation+_{create(name:"Inca Kola",info:"Inca Kola is a soft drink that was created in Peru in 1935 by British immigrant Joseph Robinson Lindley using lemon verbena (wiki)",price:1.99){id,name,info,price}}`
+
+## Read
+Get single product by id    
+`http://localhost:8080/product?query={product(id:1){name,info,price}}`
+
+Get product list    
+`http://localhost:8080/product?query={list{id,name,info,price}}`
+
+## Update
+`http://localhost:8080/product?query=mutation+_{update(id:1,price:3.95){id,name,info,price}}`
+
+## Delete
+`http://localhost:8080/product?query=mutation+_{delete(id:1){id,name,info,price}}`

examples/crud/main.go

@@ -0,0 +1,225 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"math/rand"
+	"net/http"
+	"time"
+
+	"github.com/graphql-go/graphql"
+)
+
+type Product struct {
+	ID    int64   `json:"id"`
+	Name  string  `json:"name"`
+	Info  string  `json:"info,omitempty"`
+	Price float64 `json:"price"`
+}
+
+var products []Product
+
+var productType = graphql.NewObject(
+	graphql.ObjectConfig{
+		Name: "Product",
+		Fields: graphql.Fields{
+			"id": &graphql.Field{
+				Type: graphql.Int,
+			},
+			"name": &graphql.Field{
+				Type: graphql.String,
+			},
+			"info": &graphql.Field{
+				Type: graphql.String,
+			},
+			"price": &graphql.Field{
+				Type: graphql.Float,
+			},
+		},
+	},
+)
+
+var queryType = graphql.NewObject(
+	graphql.ObjectConfig{
+		Name: "Query",
+		Fields: graphql.Fields{
+			/* Get (read) single product by id
+			   http://localhost:8080/product?query={product(id:1){name,info,price}}
+			*/
+			"product": &graphql.Field{
+				Type:        productType,
+				Description: "Get product by id",
+				Args: graphql.FieldConfigArgument{
+					"id": &graphql.ArgumentConfig{
+						Type: graphql.Int,
+					},
+				},
+				Resolve: func(p graphql.ResolveParams) (interface{}, error) {
+					id, ok := p.Args["id"].(int)
+					if ok {
+						// Find product
+						for _, product := range products {
+							if int(product.ID) == id {
+								return product, nil
+							}
+						}
+					}
+					return nil, nil
+				},
+			},
+			/* Get (read) product list
+			   http://localhost:8080/product?query={list{id,name,info,price}}
+			*/
+			"list": &graphql.Field{
+				Type:        graphql.NewList(productType),
+				Description: "Get product list",
+				Resolve: func(params graphql.ResolveParams) (interface{}, error) {
+					return products, nil
+				},
+			},
+		},
+	})
+
+var mutationType = graphql.NewObject(graphql.ObjectConfig{
+	Name: "Mutation",
+	Fields: graphql.Fields{
+		/* Create new product item
+		http://localhost:8080/product?query=mutation+_{create(name:"Inca Kola",info:"Inca Kola is a soft drink that was created in Peru in 1935 by British immigrant Joseph Robinson Lindley using lemon verbena (wiki)",price:1.99){id,name,info,price}}
+		*/
+		"create": &graphql.Field{
+			Type:        productType,
+			Description: "Create new product",
+			Args: graphql.FieldConfigArgument{
+				"name": &graphql.ArgumentConfig{
+					Type: graphql.NewNonNull(graphql.String),
+				},
+				"info": &graphql.ArgumentConfig{
+					Type: graphql.String,
+				},
+				"price": &graphql.ArgumentConfig{
+					Type: graphql.NewNonNull(graphql.Float),
+				},
+			},
+			Resolve: func(params graphql.ResolveParams) (interface{}, error) {
+				rand.Seed(time.Now().UnixNano())
+				product := Product{
+					ID:    int64(rand.Intn(100000)), // generate random ID
+					Name:  params.Args["name"].(string),
+					Info:  params.Args["info"].(string),
+					Price: params.Args["price"].(float64),
+				}
+				products = append(products, product)
+				return product, nil
+			},
+		},
+
+		/* Update product by id
+		   http://localhost:8080/product?query=mutation+_{update(id:1,price:3.95){id,name,info,price}}
+		*/
+		"update": &graphql.Field{
+			Type:        productType,
+			Description: "Update product by id",
+			Args: graphql.FieldConfigArgument{
+				"id": &graphql.ArgumentConfig{
+					Type: graphql.NewNonNull(graphql.Int),
+				},
+				"name": &graphql.ArgumentConfig{
+					Type: graphql.String,
+				},
+				"info": &graphql.ArgumentConfig{
+					Type: graphql.String,
+				},
+				"price": &graphql.ArgumentConfig{
+					Type: graphql.Float,
+				},
+			},
+			Resolve: func(params graphql.ResolveParams) (interface{}, error) {
+				id, _ := params.Args["id"].(int)
+				name, nameOk := params.Args["name"].(string)
+				info, infoOk := params.Args["info"].(string)
+				price, priceOk := params.Args["price"].(float64)
+				product := Product{}
+				for i, p := range products {
+					if int64(id) == p.ID {
+						if nameOk {
+							products[i].Name = name
+						}
+						if infoOk {
+							products[i].Info = info
+						}
+						if priceOk {
+							products[i].Price = price
+						}
+						product = products[i]
+						break
+					}
+				}
+				return product, nil
+			},
+		},
+
+		/* Delete product by id
+		   http://localhost:8080/product?query=mutation+_{delete(id:1){id,name,info,price}}
+		*/
+		"delete": &graphql.Field{
+			Type:        productType,
+			Description: "Delete product by id",
+			Args: graphql.FieldConfigArgument{
+				"id": &graphql.ArgumentConfig{
+					Type: graphql.NewNonNull(graphql.Int),
+				},
+			},
+			Resolve: func(params graphql.ResolveParams) (interface{}, error) {
+				id, _ := params.Args["id"].(int)
+				product := Product{}
+				for i, p := range products {
+					if int64(id) == p.ID {
+						product = products[i]
+						// Remove from product list
+						products = append(products[:i], products[i+1:]...)
+					}
+				}
+
+				return product, nil
+			},
+		},
+	},
+})
+
+var schema, _ = graphql.NewSchema(
+	graphql.SchemaConfig{
+		Query:    queryType,
+		Mutation: mutationType,
+	},
+)
+
+func executeQuery(query string, schema graphql.Schema) *graphql.Result {
+	result := graphql.Do(graphql.Params{
+		Schema:        schema,
+		RequestString: query,
+	})
+	if len(result.Errors) > 0 {
+		fmt.Printf("errors: %v", result.Errors)
+	}
+	return result
+}
+
+func initProductsData(p *[]Product) {
+	product1 := Product{ID: 1, Name: "Chicha Morada", Info: "Chicha morada is a beverage originated in the Andean regions of Perú but is actually consumed at a national level (wiki)", Price: 7.99}
+	product2 := Product{ID: 2, Name: "Chicha de jora", Info: "Chicha de jora is a corn beer chicha prepared by germinating maize, extracting the malt sugars, boiling the wort, and fermenting it in large vessels (traditionally huge earthenware vats) for several days (wiki)", Price: 5.95}
+	product3 := Product{ID: 3, Name: "Pisco", Info: "Pisco is a colorless or yellowish-to-amber colored brandy produced in winemaking regions of Peru and Chile (wiki)", Price: 9.95}
+	*p = append(*p, product1, product2, product3)
+}
+
+func main() {
+	// Primary data initialization
+	initProductsData(&products)
+
+	http.HandleFunc("/product", func(w http.ResponseWriter, r *http.Request) {
+		result := executeQuery(r.URL.Query().Get("query"), schema)
+		json.NewEncoder(w).Encode(result)
+	})
+
+	fmt.Println("Server is running on port 8080")
+	http.ListenAndServe(":8080", nil)
+}