feat(api): serve Metaplex coin metadata from /v1/coins/:mint/metadata

api/server.go

@@ -747,6 +747,7 @@ func NewApiServer(config config.Config) *ApiServer {
 		g.Get("/coins/volume-leaders", app.v1CoinsVolumeLeaders)
 		g.Get("/coins/:mint", app.v1Coin)
 		g.Get("/coins/ticker/:ticker", app.v1CoinByTicker)
+		g.Get("/coins/:mint/metadata", app.v1CoinMetadata)
 		g.Get("/coins/:mint/insights", app.v1CoinInsights)
 		g.Get("/coins/:mint/members", app.v1CoinsMembers)
 		g.Get("/coins/:mint/members/count", app.v1CoinMembersCount)

api/v1_coin_metadata.go

@@ -0,0 +1,85 @@
+package api
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+
+	"github.com/gofiber/fiber/v2"
+	"github.com/jackc/pgx/v5"
+)
+
+// CoinMetadata is the Metaplex Token Metadata off-chain JSON standard.
+// This is the document the DBC pool's on-chain `uri` points at for coins
+// launched after the Irys -> Audius migration, so the field names here are
+// dictated by the standard rather than by our own API conventions and the
+// response is served unwrapped (no `data` envelope).
+type CoinMetadata struct {
+	Name        string `json:"name"`
+	Symbol      string `json:"symbol"`
+	Description string `json:"description"`
+	Image       string `json:"image"`
+	ExternalUrl string `json:"external_url"`
+	Attributes  []any  `json:"attributes"`
+}
+
+func (app *ApiServer) v1CoinMetadata(c *fiber.Ctx) error {
+	mint := c.Params("mint")
+	if mint == "" {
+		return fiber.NewError(fiber.StatusBadRequest, "mint parameter is required")
+	}
+
+	var name, ticker string
+	var description, logoUri, handle *string
+	err := app.pool.QueryRow(c.Context(), `
+		SELECT artist_coins.name,
+		       artist_coins.ticker,
+		       artist_coins.description,
+		       artist_coins.logo_uri,
+		       users.handle
+		FROM artist_coins
+		LEFT JOIN users ON users.user_id = artist_coins.user_id
+		WHERE artist_coins.mint = $1
+	`, mint).Scan(&name, &ticker, &description, &logoUri, &handle)
+	if err != nil {
+		if errors.Is(err, pgx.ErrNoRows) {
+			return fiber.NewError(fiber.StatusNotFound, "Coin not found")
+		}
+		return err
+	}
+
+	appUrl := app.audiusAppUrl
+	if appUrl == "" {
+		appUrl = "https://audius.co"
+	}
+
+	metadata := CoinMetadata{
+		Name:        name,
+		Symbol:      ticker,
+		ExternalUrl: appUrl + "/coins/" + ticker,
+		Attributes:  []any{},
+	}
+	if description != nil && *description != "" {
+		metadata.Description = *description
+	} else if handle != nil {
+		// The launchpad never persists a description - the Fan Club page builds
+		// this same sentence client-side, and storing it would make the page cite
+		// itself. Regenerate it here so wallets and explorers still get one.
+		metadata.Description = defaultCoinDescription(*handle, ticker, appUrl)
+	}
+	if logoUri != nil {
+		metadata.Image = *logoUri
+	}
+
+	return c.JSON(metadata)
+}
+
+// Kept in step with LAUNCHPAD_COIN_DESCRIPTION in the web client
+// (packages/web/src/pages/fan-clubs-launchpad-page/constants.ts).
+func defaultCoinDescription(handle string, ticker string, appUrl string) string {
+	upper := strings.ToUpper(ticker)
+	return fmt.Sprintf(
+		"$%s is an artist coin created by @%s on Audius. Learn more at %s/coins/%s",
+		upper, handle, appUrl, upper,
+	)
+}

api/v1_coin_metadata_test.go

@@ -0,0 +1,90 @@
+package api
+
+import (
+	"encoding/json"
+	"testing"
+	"time"
+
+	"api.audius.co/database"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestV1CoinMetadata(t *testing.T) {
+	app := emptyTestApp(t)
+
+	fixtures := database.FixtureMap{
+		"users": {
+			{"user_id": 1, "handle": "bearartist", "is_current": true},
+			{"user_id": 2, "handle": "bareartist", "is_current": true},
+		},
+		"artist_coins": {
+			{
+				"ticker":      "BEAR",
+				"decimals":    9,
+				"user_id":     1,
+				"mint":        "9LzCMqDgTKYz9Drzqnpgee3SGa89up3a247ypMj2xrqM",
+				"name":        "Bear Coin",
+				"description": "A coin for bears",
+				"logo_uri":    "https://creatornode.audius.co/content/bear-logo-cid",
+				"created_at":  time.Now().Add(-time.Second),
+			},
+			{
+				"ticker":     "BARE",
+				"decimals":   9,
+				"user_id":    2,
+				"mint":       "3XyzCMqDgTKYz9Drzqnpgee3SGa89up3a247ypMj2xrqM",
+				"name":       "Bare Coin",
+				"created_at": time.Now().Add(-time.Second),
+			},
+		},
+	}
+
+	database.Seed(app.pool.Replicas[0], fixtures)
+
+	// Serves the Metaplex standard document, unwrapped (no "data" envelope)
+	{
+		status, body := testGet(t, app, "/v1/coins/9LzCMqDgTKYz9Drzqnpgee3SGa89up3a247ypMj2xrqM/metadata")
+		assert.Equal(t, 200, status)
+
+		var metadata CoinMetadata
+		require.NoError(t, json.Unmarshal(body, &metadata))
+		assert.Equal(t, "Bear Coin", metadata.Name)
+		assert.Equal(t, "BEAR", metadata.Symbol)
+		assert.Equal(t, "A coin for bears", metadata.Description)
+		assert.Equal(t, "https://creatornode.audius.co/content/bear-logo-cid", metadata.Image)
+		assert.Equal(t, "http://localhost:1323/coins/BEAR", metadata.ExternalUrl)
+		assert.NotNil(t, metadata.Attributes)
+
+		// The on-chain uri points here, so wallets must not see our envelope
+		var raw map[string]any
+		require.NoError(t, json.Unmarshal(body, &raw))
+		assert.NotContains(t, raw, "data")
+	}
+
+	// A coin with no stored description gets the launchpad sentence rebuilt,
+	// matching LAUNCHPAD_COIN_DESCRIPTION in the web client. Coins launched
+	// through the launchpad never persist one.
+	{
+		status, body := testGet(t, app, "/v1/coins/3XyzCMqDgTKYz9Drzqnpgee3SGa89up3a247ypMj2xrqM/metadata")
+		assert.Equal(t, 200, status)
+
+		var metadata CoinMetadata
+		require.NoError(t, json.Unmarshal(body, &metadata))
+		assert.Equal(t,
+			"$BARE is an artist coin created by @bareartist on Audius. Learn more at http://localhost:1323/coins/BARE",
+			metadata.Description)
+
+		// Nullable columns serialize as empty strings, not null
+		var raw map[string]any
+		require.NoError(t, json.Unmarshal(body, &raw))
+		assert.Equal(t, "", raw["image"])
+		assert.Equal(t, []any{}, raw["attributes"])
+	}
+
+	// Unknown mint
+	{
+		status, _ := testGet(t, app, "/v1/coins/nonexistentmint/metadata")
+		assert.Equal(t, 404, status)
+	}
+}