Complete file handling including upload flows, serving files via URL, storing generated files from actions, deletion, and accessing file metadata from system tables
npxskills add flinstech/flins--skill "Convex File Storage"Loading…
Handle file uploads, storage, serving, and management in Convex applications with proper patterns for images, documents, and generated files.
Before implementing, do not assume; fetch the latest documentation:
Convex provides built-in file storage with:
_storage system table// convex/files.ts
import { mutation } from "./_generated/server";
import { v } from "convex/values";
export const generateUploadUrl = mutation({
args: {},
returns: v.string(),
handler: async (ctx) => {
return await ctx.storage.generateUploadUrl();
},
});
// React component
import { useMutation } from "convex/react";
import { api } from "../convex/_generated/api";
import { useState } from "react";
function FileUploader() {
const generateUploadUrl = useMutation(api.files.generateUploadUrl);
const saveFile = useMutation(api.files.saveFile);
const [uploading, setUploading] = useState(false);
const handleUpload = async (e: React.ChangeEvent<HTMLInputElement>) => {
const file = e.target.files?.[0];
if (!file) return;
setUploading(true);
try {
// Step 1: Get upload URL
const uploadUrl = await generateUploadUrl();
// Step 2: Upload file to storage
const result = await fetch(uploadUrl, {
method: "POST",
headers: { "Content-Type": file.type },
body: file,
});
const { storageId } = await result.json();
// Step 3: Save file reference to database
await saveFile({
storageId,
fileName: file.name,
fileType: file.type,
fileSize: file.size,
});
} finally {
setUploading(false);
}
};
return (
<div>
<input
type="file"
onChange={handleUpload}
disabled={uploading}
/>
{uploading && <p>Uploading...</p>}
</div>
);
}
// convex/files.ts
import { mutation, query } from "./_generated/server";
import { v } from "convex/values";
export const saveFile = mutation({
args: {
storageId: v.id("_storage"),
fileName: v.string(),
fileType: v.string(),
fileSize: v.number(),
},
returns: v.id("files"),
handler: async (ctx, args) => {
return await ctx.db.insert("files", {
storageId: args.storageId,
fileName: args.fileName,
fileType: args.fileType,
fileSize: args.fileSize,
uploadedAt: Date.now(),
});
},
});
// convex/files.ts
export const getFileUrl = query({
args: { storageId: v.id("_storage") },
returns: v.union(v.string(), v.null()),
handler: async (ctx, args) => {
return await ctx.storage.getUrl(args.storageId);
},
});
// Get file with URL
export const getFile = query({
args: { fileId: v.id("files") },
returns: v.union(
v.object({
_id: v.id("files"),
fileName: v.string(),
fileType: v.string(),
fileSize: v.number(),
url: v.union(v.string(), v.null()),
}),
v.null()
),
handler: async (ctx, args) => {
const file = await ctx.db.get(args.fileId);
if (!file) return null;
const url = await ctx.storage.getUrl(file.storageId);
return {
_id: file._id,
fileName: file.fileName,
fileType: file.fileType,
fileSize: file.fileSize,
url,
};
},
});
import { useQuery } from "convex/react";
import { api } from "../convex/_generated/api";
function FileDisplay({ fileId }: { fileId: Id<"files"> }) {
const file = useQuery(api.files.getFile, { fileId });
if (!file) return <div>Loading...</div>;
if (!file.url) return <div>File not found</div>;
// Handle different file types
if (file.fileType.startsWith("image/")) {
return <img src={file.url} alt={file.fileName} />;
}
if (file.fileType === "application/pdf") {
return (
<iframe
src={file.url}
title={file.fileName}
width="100%"
height="600px"
/>
);
}
return (
<a href={file.url} download={file.fileName}>
Download {file.fileName}
</a>
);
}
// convex/generate.ts
"use node";
import { action } from "./_generated/server";
import { v } from "convex/values";
import { api } from "./_generated/api";
export const generatePDF = action({
args: { content: v.string() },
returns: v.id("_storage"),
handler: async (ctx, args) => {
// Generate PDF (example using a library)
const pdfBuffer = await generatePDFFromContent(args.content);
// Convert to Blob
const blob = new Blob([pdfBuffer], { type: "application/pdf" });
// Store in Convex
const storageId = await ctx.storage.store(blob);
return storageId;
},
});
// Generate and save image
export const generateImage = action({
args: { prompt: v.string() },
returns: v.id("_storage"),
handler: async (ctx, args) => {
// Call external API to generate image
const response = await fetch("https://api.example.com/generate", {
method: "POST",
body: JSON.stringify({ prompt: args.prompt }),
});
const imageBuffer = await response.arrayBuffer();
const blob = new Blob([imageBuffer], { type: "image/png" });
return await ctx.storage.store(blob);
},
});
// convex/files.ts
import { query } from "./_generated/server";
import { v } from "convex/values";
import { Id } from "./_generated/dataModel";
type FileMetadata = {
_id: Id<"_storage">;
_creationTime: number;
contentType?: string;
sha256: string;
size: number;
};
export const getFileMetadata = query({
args: { storageId: v.id("_storage") },
returns: v.union(
v.object({
_id: v.id("_storage"),
_creationTime: v.number(),
contentType: v.optional(v.string()),
sha256: v.string(),
size: v.number(),
}),
v.null()
),
handler: async (ctx, args) => {
const metadata = await ctx.db.system.get(args.storageId);
return metadata as FileMetadata | null;
},
});
// convex/files.ts
import { mutation } from "./_generated/server";
import { v } from "convex/values";
export const deleteFile = mutation({
args: { fileId: v.id("files") },
returns: v.null(),
handler: async (ctx, args) => {
const file = await ctx.db.get(args.fileId);
if (!file) return null;
// Delete from storage
await ctx.storage.delete(file.storageId);
// Delete database record
await ctx.db.delete(args.fileId);
return null;
},
});
import { useMutation } from "convex/react";
import { api } from "../convex/_generated/api";
import { useState, useRef } from "react";
function ImageUploader({ onUpload }: { onUpload: (id: Id<"files">) => void }) {
const generateUploadUrl = useMutation(api.files.generateUploadUrl);
const saveFile = useMutation(api.files.saveFile);
const [preview, setPreview] = useState<string | null>(null);
const [uploading, setUploading] = useState(false);
const inputRef = useRef<HTMLInputElement>(null);
const handleFileSelect = async (e: React.ChangeEvent<HTMLInputElement>) => {
const file = e.target.files?.[0];
if (!file) return;
// Validate file type
if (!file.type.startsWith("image/")) {
alert("Please select an image file");
return;
}
// Validate file size (max 10MB)
if (file.size > 10 * 1024 * 1024) {
alert("File size must be less than 10MB");
return;
}
// Show preview
const reader = new FileReader();
reader.onload = (e) => setPreview(e.target?.result as string);
reader.readAsDataURL(file);
// Upload
setUploading(true);
try {
const uploadUrl = await generateUploadUrl();
const result = await fetch(uploadUrl, {
method: "POST",
headers: { "Content-Type": file.type },
body: file,
});
const { storageId } = await result.json();
const fileId = await saveFile({
storageId,
fileName: file.name,
fileType: file.type,
fileSize: file.size,
});
onUpload(fileId);
} finally {
setUploading(false);
}
};
return (
<div>
<input
ref={inputRef}
type="file"
accept="image/*"
onChange={handleFileSelect}
style={{ display: "none" }}
/>
<button
onClick={() => inputRef.current?.click()}
disabled={uploading}
>
{uploading ? "Uploading..." : "Select Image"}
</button>
{preview && (
<img
src={preview}
alt="Preview"
style={{ maxWidth: 200, marginTop: 10 }}
/>
)}
</div>
);
}
// convex/schema.ts
import { defineSchema, defineTable } from "convex/server";
import { v } from "convex/values";
export default defineSchema({
files: defineTable({
storageId: v.id("_storage"),
fileName: v.string(),
fileType: v.string(),
fileSize: v.number(),
uploadedBy: v.id("users"),
uploadedAt: v.number(),
})
.index("by_user", ["uploadedBy"])
.index("by_type", ["fileType"]),
// User avatars
users: defineTable({
name: v.string(),
email: v.string(),
avatarStorageId: v.optional(v.id("_storage")),
}),
// Posts with images
posts: defineTable({
authorId: v.id("users"),
content: v.string(),
imageStorageIds: v.array(v.id("_storage")),
createdAt: v.number(),
}).index("by_author", ["authorId"]),
});
npx convex deploy unless explicitly instructed_storage system table only for Convex metadata
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