FastAPI from entry to actual combat (11) - form request and upload file

This article mainly records the data request of the form and related content such as uploading files of different sizes, uploading multiple files, and obtaining file information.

form request

@app07.post("/stu07/form")
def stu07_form(
        param1: str = Form(),
        param2: str = Form(),
        param3: int = Form()
):
    return {
    
    
        "param1": param1,
        "param2": param2,
        "param3": param3
    }

Consistent with the path parameters and query parameters, use the built-in Form method of fastapi to declare;

Upload a bytes file

@app07.post("/stu07/files")
def stu07_files(
        file: bytes = File()
):
    return {
    
    
        "files_size": len(file)
    }

Upload files are uploaded in the form of Form, and the File in the above code is also inherited from Form;

If the parameter type of the path operation function is declared as bytes, FastAPI will read and receive the file content in bytes.

This method stores all the contents of the file in memory and is suitable for small files.

Upload files using UploadFile

@app07.post("/stu07/uploadfile/")
def stu07_uploadfile(
        file: UploadFile
):
    return {
    
    
        "文件名": file.filename,
        "内容类型": file.content_type
    }

UploadFileCompared with bytes, it has more advantages; it is more suitable for processing large files such as images, videos, binary files, etc., and the advantage is that it does not take up all the memory;

You UploadFilecan also use attributes to get related information directly:

• filename: upload file name string (str), for example, myimage.jpg;
• content_type: content-type (MIME-type/media-type) string (str), eg, image/jpeg;
• file: SpooledTemporaryFile( file-likeobject). In fact, it is Pythona file that can be passed directly to other file-likefunctions or support libraries that expect objects.

UploadFile supports the following async methods , which (use internally SpooledTemporaryFile) call the corresponding file methods.

• write(data): data （str 或 bytes）write to the file;
• read(size)（size (int)）: Read the file content by the specified number of bytes or characters ;
• seek(offset): move to offset （int）the position of the file byte;
  • For example, await myfile.seek(0)move to the beginning of the file;
  • await myfile.read()This method is especially useful when you need to read the read content again after executing ;
• close(): Close the file.

Note :

The above methods are all asyncmethods and should be used with "await";

For example, in asyncthe path operation function, you need to read the content in the following way

contents = await myfile.read()

In ordinary defpath operation functions, you can directly accessUploadFile.file

contents = myfile.file.read()

Optional file upload

@app07.post("/stu07/optionalfile")
def stu07_optional_file(
        file: Optional[bytes] = File(None)
):
    if not file:
        return {
    
    "message": "未上传文件"}
    else:
        return {
    
    "filesize": len(file)}

Also use Optional or Union to set it;

set metadata

@app07.post("/stu07/uploadfile/metadata/")
def stu07_uploadfile_metadata(
        file: UploadFile = File(None, description="一个UploadFile文件")
):
    if not file:
        return {
    
    "message": "未上传文件"}
    else:
        return {
    
    "filename": file.filename}

This part of the content is consistent with the path parameters and query parameters, and can be set according to the requirements;

Upload multiple files

@app07.post("/stu07/fileslist")
def stu07_files_list(
        byteslist: List[bytes] = File(...),
        uploadfilelist: List[UploadFile] = File(...)
):
    return {
    
    
        "bytes_files_size": [len(file) for file in byteslist],
        "upload_filesname": [file.filename for file in uploadfilelist]
    }

To upload multiple files, set the corresponding parameter to Listtype;

Upload form parameters and files at the same time

@app07.post("/stu07/form_file/")
def stu07_form_file(
        file: UploadFile,
        form: str = Form()
):
    return {
    
    
        "filename": file.filename,
        "form": form
    }

Mixed upload, that is, declare different parameters in the corresponding path function;

source code

# -*- coding: utf-8 -*-
# @Time: 2022/11/30 18:09
# @Author: MinChess
# @File: stu07.py
# @Software: PyCharm
from fastapi import APIRouter, Form, File, UploadFile
from typing import List, Optional
from fastapi.encoders import jsonable_encoder
from pydantic import BaseModel
from datetime import datetime

app07 = APIRouter()


# 一个form请求
@app07.post("/stu07/form")
def stu07_form(
        param1: str = Form(),
        param2: str = Form(),
        param3: int = Form()
):
    return {
    
    
        "param1": param1,
        "param2": param2,
        "param3": param3
    }


# 上传一个bytes类型的文件
@app07.post("/stu07/files")
def stu07_files(
        file: bytes = File()
):
    return {
    
    
        "files_size": len(file)
    }


# 使用UploadFile
@app07.post("/stu07/uploadfile/")
def stu07_uploadfile(
        file: UploadFile
):
    return {
    
    
        "文件名": file.filename,
        "内容类型": file.content_type
    }


# 可选文件上传
@app07.post("/stu07/optionalfile")
def stu07_optional_file(
        file: Optional[bytes] = File(None)
):
    if not file:
        return {
    
    "message": "未上传文件"}
    else:
        return {
    
    "filesize": len(file)}


# 设置UploadFile元数据
@app07.post("/stu07/uploadfile/metadata/")
def stu07_uploadfile_metadata(
        file: UploadFile = File(None, description="一个UploadFile文件")
):
    if not file:
        return {
    
    "message": "未上传文件"}
    else:
        return {
    
    "filename": file.filename}


# 多文件上传
@app07.post("/stu07/fileslist")
def stu07_files_list(
        byteslist: List[bytes] = File(...),
        uploadfilelist: List[UploadFile] = File(...)
):
    return {
    
    
        "bytes_files_size": [len(file) for file in byteslist],
        "upload_filesname": [file.filename for file in uploadfilelist]
    }


# 同时上传表单和文件
@app07.post("/stu07/form_file/")
def stu07_form_file(
        file: UploadFile,
        form: str = Form()
):
    return {
    
    
        "filename": file.filename,
        "form": form
    }

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