generates something mostly plausiblegit add .

TODO

@@ -13,3 +13,4 @@ Config options:
 
 Misc:
 - replace __ with some unicode garbage
+- handle graphql errors in a reasonable way

example/README.md

@@ -0,0 +1,7 @@
+Generate the schemas by getting a token from [GitHub](https://github.com/settings/tokens/new) (no scopes needed), then:
+```
+npm install -g graphql-introspection-json-to-sdl
+curl -H "Authorization: bearer <your token>" https://api.github.com/graphql >example/schema.json
+graphql-introspection-json-to-sdl example/schema.json >example/schema.graphql
+```
+TODO: something better

example/generate_me.go

@@ -6,12 +6,14 @@ import (
 	"io/ioutil"
 	"net/http"
 	"strings"
+
+	"github.com/vektah/gqlparser/gqlerror"
 )
 
 type GetViewerResponse = struct {
 	Viewer struct {
-		Name string `json:"name"`
-	} `json:"viewer"`
+		Name *string
+	}
 }
 
 // GetViewer gets the current user's name.
@@ -42,11 +44,18 @@ query GetViewer {
 		return nil, err
 	}
 
-	retval := GetViewerResponse{}
+	var retval struct {
+		Data   GetViewerResponse `json:"data"`
+		Errors gqlerror.List     `json:"errors"`
+	}
 	err = json.Unmarshal(body, &retval)
 	if err != nil {
 		return nil, err
 	}
 
-	return &retval, nil
+	if len(retval.Errors) > 0 {
+		return nil, retval.Errors
+	}
+
+	return &retval.Data, nil
 }

generate/generate.go

@@ -1,16 +1,20 @@
 package generate
 
 import (
+	"bytes"
 	"fmt"
+	"go/format"
 	"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"
+	"github.com/vektah/gqlparser/validator"
 )
 
 // TODO: package template into the binary using one of those asset thingies
@@ -42,20 +46,43 @@ type OperationParams struct {
 	Operation string
 }
 
-func Generate(specFilename, generatedFilename string) error {
-	text, err := ioutil.ReadFile(specFilename)
+func Generate(specFilename, schemaFilename, generatedFilename string) error {
+	// TODO: IRL we have to get the schema from GraphQL (maybe we can generate
+	// that once we can bootstrap) where it comes as JSON, not SDL, so we have
+	// to convert (or add gqlparser support to convert)
+	text, err := ioutil.ReadFile(schemaFilename)
 	if err != nil {
-		return fmt.Errorf("could not open query-spec file %v: %v",
+		return fmt.Errorf("unreadable schema file %v: %v",
+			schemaFilename, err)
+	}
+
+	schema, graphqlError := gqlparser.LoadSchema(
+		&ast.Source{Name: schemaFilename, Input: string(text)})
+	if graphqlError != nil {
+		return fmt.Errorf("invalid schema file %v: %v",
+			schemaFilename, graphqlError)
+	}
+
+	text, err = ioutil.ReadFile(specFilename)
+	if err != nil {
+		return fmt.Errorf("unreadable query-spec file %v: %v",
 			specFilename, err)
 	}
 
+	// The following is more or less gqlparser.LoadQuery, but we can provide a
+	// name so we might as well (and we break out the two errors).
 	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",
+		return fmt.Errorf("invalid query-spec file %v: %v",
 			specFilename, graphqlError)
 	}
 
+	graphqlErrors := validator.Validate(schema, document)
+	if graphqlErrors != nil {
+		return fmt.Errorf("query-spec does not match schema: %v", graphqlErrors)
+	}
+
 	var out io.Writer
 	if generatedFilename == "-" {
 		out = os.Stdout
@@ -82,11 +109,14 @@ func Generate(specFilename, generatedFilename string) error {
 		operations[i] = OperationParams{
 			OperationType: operation.Operation,
 			OperationName: operation.Name,
-			OperationDoc:  "TODO",
+			// TODO: this is actually awkward, because GraphQL doesn't allow
+			// for docstrings on queries (only schemas).  So we have to extract
+			// the comment, or omit doc-comments for now.
+			OperationDoc: "TODO",
 
 			// TODO: configure this
 			ResponseName: operation.Name + "Response",
-			ResponseType: "struct{} // TODO",
+			ResponseType: typeFor(operation, schema),
 
 			Endpoint: endpoint,
 			// The newline just makes it format a little nicer
@@ -99,11 +129,19 @@ func Generate(specFilename, generatedFilename string) error {
 		Operations:  operations,
 	}
 
-	err = tmpl.Execute(out, data)
+	var buf bytes.Buffer
+	err = tmpl.Execute(&buf, data)
 	if err != nil {
 		return fmt.Errorf("could not render template: %v", err)
 	}
-	return nil
+
+	formatted, err := format.Source(buf.Bytes())
+	if err != nil {
+		return fmt.Errorf("could not gofmt template: %v", err)
+	}
+
+	_, err = out.Write(formatted)
+	return err
 }
 
 func Main() {
@@ -115,9 +153,10 @@ func Main() {
 		}
 	}()
 
-	if len(os.Args) != 3 {
-		err = fmt.Errorf("usage: %s queries.graphql generated.go", os.Args[0])
+	if len(os.Args) != 4 {
+		err = fmt.Errorf("usage: %s queries.graphql schema.graphqll generated.go",
+			os.Args[0])
 		return
 	}
-	err = Generate(os.Args[1], os.Args[2])
+	err = Generate(os.Args[1], os.Args[2], os.Args[3])
 }

generate/operation.go.tmpl

@@ -6,6 +6,8 @@ import (
 	"io/ioutil"
 	"net/http"
 	"strings"
+
+	"github.com/vektah/gqlparser/gqlerror"
 )
 
 {{range .Operations}}
@@ -33,12 +35,19 @@ func {{.OperationName}}(ctx context.Context) (*{{.ResponseName}}, error) {
 		return nil, err
 	}
 
-	retval := {{.ResponseName}}{}
+	var retval struct {
+		Data   {{.ResponseName}} `json:"data"`
+		Errors gqlerror.List     `json:"errors"`
+	}
 	err = json.Unmarshal(body, &retval)
 	if err != nil {
 		return nil, err
 	}
 
-	return &retval, nil
+	if len(retval.Errors) > 0 {
+		return nil, retval.Errors
+	}
+
+	return &retval.Data, nil
 }
 {{end}}

generate/types.go

@@ -0,0 +1,66 @@
+package generate
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/vektah/gqlparser/ast"
+)
+
+func typeFor(operation *ast.OperationDefinition, schema *ast.Schema) string {
+	var builder strings.Builder
+
+	writeSelectionSetStruct(&builder, operation.SelectionSet, schema)
+
+	return builder.String()
+}
+
+func writeSelectionSetStruct(builder *strings.Builder, selectionSet ast.SelectionSet, schema *ast.Schema) {
+	builder.WriteString("struct {\n")
+	for _, selection := range selectionSet {
+		switch selection := selection.(type) {
+		case *ast.Field:
+			// TODO: assert it starts with uppercase (or do automatically if
+			// alias is not provided; in this case we may need json tags to
+			// avoid munging the query)
+			if selection.Alias != "" {
+				builder.WriteString(selection.Alias)
+			} else {
+				builder.WriteString(selection.Name)
+			}
+			builder.WriteRune(' ')
+
+			writeType(builder, selection.Definition.Type, selection.SelectionSet, schema)
+
+			// We don't need a json tag -- we just have GraphQL do the
+			// aliasing.
+			builder.WriteRune('\n')
+
+		case *ast.FragmentSpread, *ast.InlineFragment:
+			panic("TODO")
+		default:
+			panic(fmt.Errorf("invalid selection type: %v", selection))
+		}
+	}
+	builder.WriteString("}")
+}
+
+func writeType(builder *strings.Builder, typ *ast.Type, selectionSet ast.SelectionSet, schema *ast.Schema) {
+	if typ.Elem != nil {
+		// Type is a list.
+		builder.WriteString("[]")
+		typ = typ.Elem
+	} else if !typ.NonNull { // no need for pointer if we have a list
+		builder.WriteString("*")
+	}
+
+	if selectionSet != nil {
+		writeSelectionSetStruct(builder, selectionSet, schema)
+		return
+	}
+
+	// TODO: actually handle scalars.  or can we instead use gqlgen's
+	// converter?  they're doing mostly the same thing.  if not, crib from it:
+	// https://github.com/99designs/gqlgen/blob/master/plugin/modelgen/models.go#L113
+	builder.WriteString(strings.ToLower(typ.Name()))
+}