feat: Add UploadReleaseAssetFromRelease convenience helper

example/uploadreleaseassetfromrelease/main.go

@@ -0,0 +1,61 @@
+// Copyright 2025 The go-github AUTHORS. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// The uploadreleaseassetfromrelease example demonstrates how to upload
+// a release asset using the UploadReleaseAssetFromRelease helper.
+package main
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"log"
+	"os"
+
+	"github.com/google/go-github/v80/github"
+)
+
+func main() {
+	token := os.Getenv("GITHUB_AUTH_TOKEN")
+	if token == "" {
+		log.Fatal("GITHUB_AUTH_TOKEN not set")
+	}
+
+	ctx := context.Background()
+	client := github.NewClient(nil).WithAuthToken(token)
+
+	owner := "OWNER"
+	repo := "REPO"
+	releaseID := int64(1)
+
+	// Fetch the release (UploadURL is populated by the API)
+	release, _, err := client.Repositories.GetRelease(ctx, owner, repo, releaseID)
+	if err != nil {
+		log.Fatalf("GetRelease failed: %v", err)
+	}
+
+	// Asset content
+	data := []byte("Hello from go-github!\n")
+	reader := bytes.NewReader(data)
+	size := int64(len(data))
+
+	opts := &github.UploadOptions{
+		Name:  "example.txt",
+		Label: "Example asset",
+	}
+
+	asset, _, err := client.Repositories.UploadReleaseAssetFromRelease(
+		ctx,
+		release,
+		opts,
+		reader,
+		size,
+	)
+	if err != nil {
+		log.Fatalf("UploadReleaseAssetFromRelease failed: %v", err)
+	}
+
+	fmt.Printf("Uploaded asset ID: %v\n", asset.GetID())
+}

github/repos_releases.go

@@ -488,3 +488,76 @@ func (s *RepositoriesService) UploadReleaseAsset(ctx context.Context, owner, rep
 	}
 	return asset, resp, nil
 }
+
+// UploadReleaseAssetFromRelease uploads an asset using the UploadURL that's embedded
+// in a RepositoryRelease object.
+//
+// This is a convenience wrapper that extracts the release.UploadURL (which is usually
+// templated like "https://uploads.github.com/.../assets{?name,label}") and uploads
+// the provided data (reader + size) using the existing upload helpers.
+//
+// GitHub API docs: https://docs.github.com/rest/releases/assets#upload-a-release-asset
+//
+//meta:operation POST /repos/{owner}/{repo}/releases/{release_id}/assets
+func (s *RepositoriesService) UploadReleaseAssetFromRelease(
+	ctx context.Context,
+	release *RepositoryRelease,
+	opts *UploadOptions,
+	reader io.Reader,
+	size int64,
+) (*ReleaseAsset, *Response, error) {
+	if release == nil || release.UploadURL == nil {
+		return nil, nil, errors.New("release UploadURL must be provided")
+	}
+	if reader == nil {
+		return nil, nil, errors.New("reader must be provided")
+	}
+	if size < 0 {
+		return nil, nil, errors.New("size must be >= 0")
+	}
+
+	// Strip URI-template portion (e.g. "{?name,label}") if present.
+	uploadURL := *release.UploadURL
+	if idx := strings.Index(uploadURL, "{"); idx != -1 {
+		uploadURL = uploadURL[:idx]
+	}
+
+	// If this is a *relative* URL (no scheme), normalize it by trimming a leading "/"
+	// so it works with Client.BaseURL path prefixes (e.g. "/api-v3/").
+	if !strings.HasPrefix(uploadURL, "http://") && !strings.HasPrefix(uploadURL, "https://") {
+		uploadURL = strings.TrimPrefix(uploadURL, "/")
+	}
+
+	// addOptions will append name/label query params (same behavior as UploadReleaseAsset).
+	u, err := addOptions(uploadURL, opts)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	// determine media type
+	mediaType := defaultMediaType
+	if opts != nil {
+		switch {
+		case opts.MediaType != "":
+			mediaType = opts.MediaType
+		case opts.Name != "":
+			if ext := filepath.Ext(opts.Name); ext != "" {
+				if mt := mime.TypeByExtension(ext); mt != "" {
+					mediaType = mt
+				}
+			}
+		}
+	}
+
+	req, err := s.client.NewUploadRequest(u, reader, size, mediaType)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	asset := new(ReleaseAsset)
+	resp, err := s.client.Do(ctx, req, asset)
+	if err != nil {
+		return nil, resp, err
+	}
+	return asset, resp, nil
+}

github/repos_releases_test.go

@@ -930,3 +930,206 @@ func TestGenerateNotesOptions_Marshal(t *testing.T) {
 
 	testJSONMarshal(t, u, want)
 }
+
+func TestRepositoriesService_UploadReleaseAssetFromRelease(t *testing.T) {
+	t.Parallel()
+
+	var (
+		defaultUploadOptions     = &UploadOptions{Name: "n.txt"}
+		defaultExpectedFormValue = values{"name": "n.txt"}
+		mediaTypeTextPlain       = "text/plain; charset=utf-8"
+	)
+
+	client, mux, _ := setup(t)
+
+	// Use the same endpoint path used in other release asset tests.
+	mux.HandleFunc("/repos/o/r/releases/1/assets", func(w http.ResponseWriter, r *http.Request) {
+		testMethod(t, r, "POST")
+		testHeader(t, r, "Content-Type", mediaTypeTextPlain)
+		testHeader(t, r, "Content-Length", "12")
+		testFormValues(t, r, defaultExpectedFormValue)
+		testBody(t, r, "Upload me !\n")
+
+		fmt.Fprint(w, `{"id":1}`)
+	})
+
+	body := []byte("Upload me !\n")
+	reader := bytes.NewReader(body)
+	size := int64(len(body))
+
+	// Provide a templated upload URL like GitHub returns.
+	uploadURL := "/repos/o/r/releases/1/assets{?name,label}"
+	release := &RepositoryRelease{
+		UploadURL: &uploadURL,
+	}
+
+	ctx := t.Context()
+	asset, _, err := client.Repositories.UploadReleaseAssetFromRelease(ctx, release, defaultUploadOptions, reader, size)
+	if err != nil {
+		t.Fatalf("Repositories.UploadReleaseAssetFromRelease returned error: %v", err)
+	}
+	want := &ReleaseAsset{ID: Ptr(int64(1))}
+	if !cmp.Equal(asset, want) {
+		t.Fatalf("Repositories.UploadReleaseAssetFromRelease returned %+v, want %+v", asset, want)
+	}
+}
+
+func TestRepositoriesService_UploadReleaseAssetFromRelease_AbsoluteTemplate(t *testing.T) {
+	t.Parallel()
+	client, mux, _ := setup(t)
+
+	mux.HandleFunc("/repos/o/r/releases/1/assets", func(w http.ResponseWriter, r *http.Request) {
+		testMethod(t, r, "POST")
+		// Expect name query param created by addOptions after trimming template.
+		if got := r.URL.Query().Get("name"); got != "abs.txt" {
+			t.Errorf("Expected name query param 'abs.txt', got %q", got)
+		}
+		fmt.Fprint(w, `{"id":1}`)
+	})
+
+	body := []byte("Upload me !\n")
+	reader := bytes.NewReader(body)
+	size := int64(len(body))
+
+	// Build an absolute URL using the test client's BaseURL.
+	absoluteUploadURL := client.BaseURL.String() + "repos/o/r/releases/1/assets{?name,label}"
+	release := &RepositoryRelease{UploadURL: &absoluteUploadURL}
+
+	opts := &UploadOptions{Name: "abs.txt"}
+	ctx := t.Context()
+	asset, _, err := client.Repositories.UploadReleaseAssetFromRelease(ctx, release, opts, reader, size)
+	if err != nil {
+		t.Fatalf("UploadReleaseAssetFromRelease returned error: %v", err)
+	}
+	want := &ReleaseAsset{ID: Ptr(int64(1))}
+	if !cmp.Equal(asset, want) {
+		t.Fatalf("UploadReleaseAssetFromRelease returned %+v, want %+v", asset, want)
+	}
+}
+
+func TestRepositoriesService_UploadReleaseAssetFromRelease_NilRelease(t *testing.T) {
+	t.Parallel()
+	client, _, _ := setup(t)
+
+	body := []byte("Upload me !\n")
+	reader := bytes.NewReader(body)
+	size := int64(len(body))
+
+	ctx := t.Context()
+	_, _, err := client.Repositories.UploadReleaseAssetFromRelease(ctx, nil, &UploadOptions{Name: "n.txt"}, reader, size)
+	if err == nil {
+		t.Fatal("expected error for nil release, got nil")
+	}
+
+	const methodName = "UploadReleaseAssetFromRelease"
+	testBadOptions(t, methodName, func() (err error) {
+		_, _, err = client.Repositories.UploadReleaseAssetFromRelease(ctx, nil, &UploadOptions{Name: "n.txt"}, reader, size)
+		return err
+	})
+}
+
+func TestRepositoriesService_UploadReleaseAssetFromRelease_NilReader(t *testing.T) {
+	t.Parallel()
+	client, _, _ := setup(t)
+
+	uploadURL := "/repos/o/r/releases/1/assets{?name,label}"
+	release := &RepositoryRelease{UploadURL: &uploadURL}
+
+	ctx := t.Context()
+	_, _, err := client.Repositories.UploadReleaseAssetFromRelease(ctx, release, &UploadOptions{Name: "n.txt"}, nil, 12)
+	if err == nil {
+		t.Fatal("expected error when reader is nil")
+	}
+
+	const methodName = "UploadReleaseAssetFromRelease"
+	testBadOptions(t, methodName, func() (err error) {
+		_, _, err = client.Repositories.UploadReleaseAssetFromRelease(ctx, release, &UploadOptions{Name: "n.txt"}, nil, 12)
+		return err
+	})
+}
+
+func TestRepositoriesService_UploadReleaseAssetFromRelease_NegativeSize(t *testing.T) {
+	t.Parallel()
+	client, _, _ := setup(t)
+
+	uploadURL := "/repos/o/r/releases/1/assets{?name,label}"
+	release := &RepositoryRelease{UploadURL: &uploadURL}
+
+	body := []byte("Upload me !\n")
+	reader := bytes.NewReader(body)
+
+	ctx := t.Context()
+	_, _, err := client.Repositories.UploadReleaseAssetFromRelease(ctx, release, &UploadOptions{Name: "n..txt"}, reader, -1)
+	if err == nil {
+		t.Fatal("expected error when size is negative")
+	}
+}
+
+func TestRepositoriesService_UploadReleaseAssetFromRelease_NoOpts(t *testing.T) {
+	t.Parallel()
+	client, mux, _ := setup(t)
+
+	// No opts: we just assert that the handler is hit and body is as expected.
+	mux.HandleFunc("/repos/o/r/releases/1/assets", func(w http.ResponseWriter, r *http.Request) {
+		testMethod(t, r, "POST")
+		testBody(t, r, "Upload me !\n")
+		fmt.Fprint(w, `{"id":1}`)
+	})
+
+	body := []byte("Upload me !\n")
+	reader := bytes.NewReader(body)
+	size := int64(len(body))
+
+	uploadURL := "/repos/o/r/releases/1/assets{?name,label}"
+	release := &RepositoryRelease{UploadURL: &uploadURL}
+
+	ctx := t.Context()
+	asset, _, err := client.Repositories.UploadReleaseAssetFromRelease(ctx, release, nil, reader, size)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	want := &ReleaseAsset{ID: Ptr(int64(1))}
+	if !cmp.Equal(asset, want) {
+		t.Fatalf("Repositories.UploadReleaseAssetFromRelease returned %+v, want %+v", asset, want)
+	}
+
+	const methodName = "UploadReleaseAssetFromRelease"
+	testNewRequestAndDoFailure(t, methodName, client, func() (*Response, error) {
+		got, resp, err := client.Repositories.UploadReleaseAssetFromRelease(ctx, release, nil, reader, size)
+		if got != nil {
+			t.Errorf("testNewRequestAndDoFailure %v = %#v, want nil", methodName, got)
+		}
+		return resp, err
+	})
+}
+
+func TestRepositoriesService_UploadReleaseAssetFromRelease_WithMediaType(t *testing.T) {
+	t.Parallel()
+	client, mux, _ := setup(t)
+
+	// Expect explicit media type to be used.
+	mux.HandleFunc("/repos/o/r/releases/1/assets", func(w http.ResponseWriter, r *http.Request) {
+		testMethod(t, r, "POST")
+		testHeader(t, r, "Content-Type", "image/png")
+		fmt.Fprint(w, `{"id":1}`)
+	})
+
+	body := []byte("Binary!")
+	reader := bytes.NewReader(body)
+	size := int64(len(body))
+
+	uploadURL := "/repos/o/r/releases/1/assets{?name,label}"
+	release := &RepositoryRelease{UploadURL: &uploadURL}
+
+	opts := &UploadOptions{Name: "n.txt", MediaType: "image/png"}
+
+	ctx := t.Context()
+	asset, _, err := client.Repositories.UploadReleaseAssetFromRelease(ctx, release, opts, reader, size)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	want := &ReleaseAsset{ID: Ptr(int64(1))}
+	if !cmp.Equal(asset, want) {
+		t.Fatalf("UploadReleaseAssetFromRelease returned %+v, want %+v", asset, want)
+	}
+}