fill out the easy parts of the codegen

cmd/genql/main.go

@@ -1,16 +1,9 @@
 package main
 
 import (
-	"fmt"
-	"os"
-
 	"github.com/Khan/genql/generate"
 )
 
 func main() {
-	err := generate.Generate()
-	if err != nil {
-		fmt.Println(fmt.Errorf("genql failed: %v", err))
-		os.Exit(1)
-	}
+	generate.Main()
 }

example/generate_me.go

@@ -20,11 +20,10 @@ func GetViewer(ctx context.Context) (*GetViewerResponse, error) {
 		http.MethodPost,
 		`https://api.github.com/graphql`,
 		strings.NewReader(`
-"GetViewer gets the current user's name."
 query GetViewer {
-  Viewer: viewer {
-    Name: name
-  }
+	Viewer: viewer {
+		Name: name
+	}
 }
 `))
 	if err != nil {

example/queries.graphql

@@ -1,4 +1,4 @@
-"GetViewer gets the current user's name."
+# GetViewer gets the current user's name.
 query GetViewer {
   Viewer: viewer {
     Name: name

generate/generate.go

@@ -2,41 +2,122 @@ package generate
 
 import (
 	"fmt"
+	"io"
+	"io/ioutil"
 	"os"
+	"strings"
 	"text/template"
 
-	"github.com/vektah/gqlparser"
+	"github.com/vektah/gqlparser/ast"
+	"github.com/vektah/gqlparser/formatter"
+	"github.com/vektah/gqlparser/parser"
 )
 
-var _ = gqlparser.LoadSchema
-
 // TODO: package template into the binary using one of those asset thingies
 const tmplFilename = "generate/operation.go.tmpl"
 
+var tmpl = template.Must(template.ParseFiles(tmplFilename))
+
 type TemplateParams struct {
 	// The name of the package into which to generate the operation-helpers.
 	PackageName string
+	// The list of operations for which to generate code.
+	Operations []OperationParams
+}
+
+type OperationParams struct {
 	// The type-name for the operation's response type.
 	ResponseName string
 	// The body of the operation's response type (e.g. struct { ... }).
 	ResponseType string
-	// The documentation for the operation, from GraphQL.
-	OperationDoc string
+	// The type of the operation (query, mutation, or subscription).
+	OperationType ast.Operation
 	// The name of the operation, from GraphQL.
 	OperationName string
+	// The documentation for the operation, from GraphQL.
+	OperationDoc string
 	// The endpoint to which to send queries.
 	Endpoint string
 	// The body of the operation to send.
 	Operation string
 }
 
-var tmpl = template.Must(template.ParseFiles(tmplFilename))
-
-func Generate() error {
-	var data TemplateParams
-	err := tmpl.Execute(os.Stdout, data)
+func Generate(specFilename, generatedFilename string) error {
+	text, err := ioutil.ReadFile(specFilename)
 	if err != nil {
-		return fmt.Errorf("template did not render: %v", err)
+		return fmt.Errorf("could not open query-spec file %v: %v",
+			specFilename, err)
+	}
+
+	document, graphqlError := parser.ParseQuery(
+		&ast.Source{Name: specFilename, Input: string(text)})
+	if graphqlError != nil { // ParseQuery returns type *graphql.Error, yuck
+		return fmt.Errorf("could not parse query-spec file %v: %v",
+			specFilename, graphqlError)
+	}
+
+	var out io.Writer
+	if generatedFilename == "-" {
+		out = os.Stdout
+	} else {
+		out, err = os.OpenFile(generatedFilename, os.O_RDWR|os.O_CREATE, 0755)
+		if err != nil {
+			return fmt.Errorf("could not open generated file %v: %v",
+				generatedFilename, err)
+		}
+	}
+
+	// TODO: configure these
+	packageName := "example"
+	endpoint := "https://api.github.com/graphql"
+
+	operations := make([]OperationParams, len(document.Operations))
+	for i, operation := range document.Operations {
+		var builder strings.Builder
+		f := formatter.NewFormatter(&builder)
+		f.FormatQueryDocument(&ast.QueryDocument{
+			Operations: ast.OperationList{operation},
+			// TODO: handle fragments
+		})
+		operations[i] = OperationParams{
+			OperationType: operation.Operation,
+			OperationName: operation.Name,
+			OperationDoc:  "TODO",
+
+			// TODO: configure this
+			ResponseName: operation.Name + "Response",
+			ResponseType: "struct{} // TODO",
+
+			Endpoint: endpoint,
+			// The newline just makes it format a little nicer
+			Operation: "\n" + builder.String(),
+		}
+	}
+
+	data := TemplateParams{
+		PackageName: packageName,
+		Operations:  operations,
+	}
+
+	err = tmpl.Execute(out, data)
+	if err != nil {
+		return fmt.Errorf("could not render template: %v", err)
 	}
 	return nil
 }
+
+func Main() {
+	var err error
+	defer func() {
+		if err != nil {
+			fmt.Println(err)
+			os.Exit(1)
+		}
+	}()
+
+	if len(os.Args) != 3 {
+		err = fmt.Errorf("usage: %s queries.graphql generated.go", os.Args[0])
+		return
+	}
+	err = Generate(os.Args[1], os.Args[2])
+}

generate/operation.go.tmpl

@@ -8,6 +8,7 @@ import (
 	"strings"
 )
 
+{{range .Operations}}
 type {{.ResponseName}} = {{.ResponseType}}
 
 // {{.OperationDoc}}
@@ -20,7 +21,7 @@ func {{.OperationName}}(ctx context.Context) (*{{.ResponseName}}, error) {
 		return nil, err
 	}
 
-    req = req.WithContext(ctx)
+	req = req.WithContext(ctx)
 	resp, err := http.DefaultClient.Do(req)
 	if err != nil {
 		return nil, err
@@ -40,3 +41,4 @@ func {{.OperationName}}(ctx context.Context) (*{{.ResponseName}}, error) {
 
 	return &retval, nil
 }
+{{end}}