使用 nexus-prisma graphql 处理文件上传答案

【问题标题】：Handling file upload with nexus-prisma graphql使用 nexus-prisma graphql 处理文件上传
【发布时间】：2020-09-06 16:04:14
【问题描述】：

我正在尝试将文件从我的前端应用上传到我的服务器但我不断收到这个奇怪的错误，不知道为什么会这样。

错误是前端：

Variable "$file" got invalid value {}; Expected type Upload. Upload value invalid.

后端出错：

GraphQLError: Upload value invalid.
at GraphQLScalarType.parseValue (/app/backend/node_modules/graphql-upload/lib/GraphQLUpload.js:66:11)

这就是我添加上传标量的方式


// scalars/upload.ts
import { scalarType } from "nexus/dist";
import { GraphQLUpload } from "graphql-upload";

export const Upload = scalarType({
  name: "Upload",
  asNexusMethod: "upload", // We set this to be used as a method later as `t.upload()` if needed
  description: GraphQLUpload.description,
  serialize: GraphQLUpload.serialize,
  parseValue: GraphQLUpload.parseValue,
  parseLiteral: GraphQLUpload.parseLiteral,
});

export default Upload;

// scalar/index.ts
export { default as Upload } from "./Upload";

// index.ts
import * as allTypes from "./resolvers";
import * as scalars from "./scalars";
const schema = makePrismaSchema({
  types: [scalars, allTypes],
  prisma: {
    datamodelInfo,
    client: prisma,
  },
...

// my mutation 
t.string("uploadFile", {
  args: {
    file: arg({ type: "Upload", nullable: false }),
  },
  resolve: async (_: any, { file }, {  }: any) => {
    console.log(file);
    return "ok";
  },
});

这就是我在我的 React/NextJS 应用程序中制作 uplaod 客户端的方式

// the link
const link = () => {
  return createUploadLink({
    uri: process.env.backend,
    credentials: "include",
    fetch,
  });
};

// the mutation ( I use graphql codegen )

mutation TestUpload($file: Upload!) {
  uploadFile(file: $file)
}

const [upload] = useTestUploadMutation();

<input
  type="file"
  onChange={(e) => {
    const { files, validity } = e.target;
    if (validity.valid && files && files[0]) {
      upload({
        variables: {
          file: files[0],
        },
      });
    }
  }}
/>

即使尝试使用我的前端应用程序以外的其他东西运行突变，我也会遇到同样的错误，所以我猜问题出在我的后端设置上，即使我搜索了很多方法来做到这一点，但似乎没有一个工作。

【问题讨论】：

标签： graphql apollo prisma prisma-graphql nexus-prisma

【解决方案1】：

我刚刚遇到了完全相同的问题。这解决了它。所以基本上手动定义上传而不是使用 GraphQLUpload

import { objectType, scalarType } from "@nexus/schema";
import { GraphQLError } from "graphql";
import * as FileType from "file-type";

export const Upload = scalarType({
  name: "Upload",
  asNexusMethod: "upload", // We set this to be used as a method later as `t.upload()` if needed
  description: "desc",
  serialize: () => {
    throw new GraphQLError("Upload serialization unsupported.");
  },
  parseValue: async (value) => {
    const upload = await value;
    const stream = upload.createReadStream();
    const fileType = await FileType.fromStream(stream);

    if (fileType?.mime !== upload.mimetype)
      throw new GraphQLError("Mime type does not match file content.");

    return upload;
  },
  parseLiteral: (ast) => {
    throw new GraphQLError("Upload literal unsupported.", ast);
  },
});

export const File = objectType({
  name: "File",
  definition(t) {
    t.id("id");
    t.string("path");
    t.string("filename");
    t.string("mimetype");
    t.string("encoding");
  },
});

【讨论】：