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Convex File Storage

Convex 文件存储

Handle file uploads, storage, serving, and management in Convex applications with proper patterns for images, documents, and generated files.
在Convex应用中使用适用于图片、文档和生成文件的规范模式，处理文件上传、存储、服务与管理。

Documentation Sources

文档来源

Before implementing, do not assume; fetch the latest documentation:
在实现之前，不要凭假设操作，请获取最新文档：

Instructions

操作说明

File Storage Overview

文件存储概述

Convex provides built-in file storage with:
  • Automatic URL generation for serving files
  • Support for any file type (images, PDFs, videos, etc.)
  • File metadata via the 
    _storage
    system table
  • Integration with mutations and actions
Convex 提供内置的文件存储功能，包括：
  • 自动生成用于文件服务的URL
  • 支持任意文件类型（图片、PDF、视频等）
  • 通过
    _storage
    系统表获取文件元数据
  • 与mutation和action集成

Generating Upload URLs

生成上传URL

typescript
// 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();
  },
});
typescript
// 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();
  },
});

Client-Side Upload

客户端上传

typescript
// 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>
  );
}
typescript
// 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>
  );
}

Saving File References

保存文件引用

typescript
// 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(),
    });
  },
});
typescript
// 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(),
    });
  },
});

Serving Files via URL

通过URL提供文件服务

typescript
// 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,
    };
  },
});
typescript
// 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,
    };
  },
});

Displaying Files in React

在React中展示文件

typescript
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>
  );
}
typescript
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>
  );
}

Storing Generated Files from Actions

存储由操作生成的文件

typescript
// 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);
  },
});
typescript
// 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);
  },
});

Accessing File Metadata

访问文件元数据

typescript
// 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;
  },
});
typescript
// 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;
  },
});

Deleting Files

删除文件

typescript
// 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;
  },
});
typescript
// 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;
  },
});

Image Upload with Preview

带预览的图片上传

typescript
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>
  );
}
typescript
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>
  );
}

Examples

示例

Schema for File Storage

文件存储Schema

typescript
// 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"]),
});
typescript
// 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"]),
});

Best Practices

最佳实践

  • Never run 
    npx convex deploy
    unless explicitly instructed
  • Never run any git commands unless explicitly instructed
  • Validate file types and sizes on the client before uploading
  • Store file metadata (name, type, size) in your own table
  • Use the 
    _storage
    system table only for Convex metadata
  • Delete storage files when deleting database references
  • Use appropriate Content-Type headers when uploading
  • Consider image optimization for large images
  • 除非明确指示，否则不要运行
    npx convex deploy
  • 除非明确指示，否则不要运行任何git命令
  • 在上传前在客户端验证文件类型和大小
  • 在自己的表中存储文件元数据（名称、类型、大小）
  • 仅将
    _storage
    系统表用于Convex元数据
  • 删除数据库记录时同时删除存储中的文件
  • 上传时使用正确的Content-Type头
  • 考虑对大图片进行优化

Common Pitfalls

常见陷阱

  1. Not setting Content-Type header - Files may not serve correctly
  2. Forgetting to delete storage - Orphaned files waste storage
  3. Not validating file types - Security risk for malicious uploads
  4. Large file uploads without progress - Poor UX for users
  5. Using deprecated getMetadata - Use ctx.db.system.get instead
  1. 未设置Content-Type头 - 文件可能无法正常提供服务
  2. 忘记删除存储文件 - 孤立文件会浪费存储空间
  3. 未验证文件类型 - 存在恶意上传的安全风险
  4. 大文件上传无进度提示 - 给用户带来糟糕的体验
  5. 使用已弃用的getMetadata - 请改用ctx.db.system.get

References

参考资料