所需的 MultipartFile 参数“文件”不存在 [Postman 和 Springboot]

Question

I'm passing a csv file as a parameter, but it is not being received at the backend code. I've looked into multiple available solutions, but none of them seemed to work for me. Here's the code:

@PostMapping(value = "/import",  consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
public Object uploadCSVFile(@RequestParam("file") MultipartFile csvFile, Model model) {
    String response = "";
    Object obj = null;
    if (csvFile.isEmpty()) {
        model.addAttribute("message", "Please select a CSV file to upload.");
        model.addAttribute("status", false);
    } else {
        try{
               //doo foo
            }
        catch (Exception e){
            System.out.println(e.getStackTrace());
        }
    }
    return obj;
}

Here are the dependencies in pom.xml if it's required for reference:

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-r2dbc</artifactId>
    </dependency>
    <dependency>
        <groupId>io.r2dbc</groupId>
        <artifactId>r2dbc-h2</artifactId>
        <scope>runtime</scope>
    </dependency>
    <!-- Apache Commons FileUpload -->
    <dependency>
        <groupId>commons-fileupload</groupId>
        <artifactId>commons-fileupload</artifactId>
        <version>1.3.1</version>
    </dependency>
    <!-- Apache Commons IO -->
    <dependency>
        <groupId>commons-io</groupId>
        <artifactId>commons-io</artifactId>
        <version>2.4</version>
    </dependency>
    <dependency>
        <groupId>com.h2database</groupId>
        <artifactId>h2</artifactId>
    </dependency>
    <dependency>
        <groupId>com.opencsv</groupId>
        <artifactId>opencsv</artifactId>
        <version>5.0</version>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-mail</artifactId>
        <version>2.2.5.RELEASE</version>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-webflux</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-devtools</artifactId>
        <scope>runtime</scope>
        <optional>true</optional>
    </dependency>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <optional>true</optional>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>io.projectreactor</groupId>
        <artifactId>reactor-test</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.apache.tomcat.embed</groupId>
        <artifactId>tomcat-embed-core</artifactId>
        <version>9.0.39</version>
    </dependency>
    <dependency>
        <groupId>org.apache.commons</groupId>
        <artifactId>commons-csv</artifactId>
        <version>1.8</version>
    </dependency>
    <dependency>
        <groupId>org.jetbrains</groupId>
        <artifactId>annotations</artifactId>
        <version>RELEASE</version>
        <scope>compile</scope>
    </dependency>
    <dependency>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.8.1</version>
    </dependency>
</dependencies>

Even on using "required=false" in the @RequestParam annotation, turns out the Multipart file is null, even though the inspect tool displays having sent it as a request. Any help is appreciated!

PS: Postman Snip:

Headers snip:

Answer 1

Simple answer, try using @RequestPart("file") instead of @RequestParam("file") . See documentation here: https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/web/bind/annotation/RequestPart.html

Answer 2

Turns out, the comment from @BERGUIGAMohamedAmine made me realize that MultiPart is either not compatible / or has some issues with Spring webflux. In my case, I changed MultiPart to FilePart, and things are now working fine. Here's the updated body:

@PostMapping(value = "/import",  consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
    public Object uploadCSVFile(@RequestPart("file") FilePart file, Model model) {
        //do foo
}

PS: @RequestParam can be used instead of @RequestPart, but it made sense to use it since we are trying to send a Part as a parameter, so I used it:]