“JSON parse error: Cannot deserialize value of type `java.util.ArrayList＜XXX＞` from Object value ...

桃扇骨 2023-09-27 12:37 117阅读 0赞

"JSON parse error: Cannot deserialize value of type \`java.util.ArrayList<xxx>\` from Object value (token \`JsonToken.START\_OBJECT\`); nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize value of type \`java.util.ArrayList<xxx>\` from Object value (token \`JsonToken.START\_OBJECT\`)\\n at \[Source: (org.springframework.util.StreamUtils$NonClosingInputStream); line: 3, column: 22\] (through reference chain: cn.com.sinosoft.entity.dto.EnclosureUploadDTO\[\\"enclosureList\\"\])",

今天周末加班改bug时，用postman传参遇到上述一个错误，搞了我十分钟。。。今天分享给大家避免踩坑

首先我的controller类如下

// 上传附件
        @PostMapping("/upload")
        public R upload(@RequestBody EnclosureUploadDTO uploadDTO){
            internalProjectService.uploadEnclosure(uploadDTO);
            return R.ok();
        }

EnclosureUploadDTO里面有这几个参数

@Data
    public class EnclosureUploadDTO {
        private String id;
    
        /**
         * 完成情况说明
         */
        private String completionDescription;
    
        private List<Enclosure> enclosureList;
    }

可以看到enclosureList是一个集合形式的数据

给大家看下我用postman传参方式

![d0ecbaf4400d41c0b712bb5870a4baa2.png][]

错误传参方式：

{
        "id": "1590593194199277570",
        "enclosureList": {
            "enclosureName": "soft.pdf",
            "enclosureType": 21,
            "enclosureId": "1591262808073314362",
            "url": "www.baidu.com"
        }
    }

乍一看没啥问题啊，一执行的时候就报告错误

{
    
        "code": 500,
    
        "msg": "JSON parse error: Cannot deserialize value of type `java.util.ArrayList<cn.com.sinosoft.entity.Enclosure>` from Object value (token `JsonToken.START_OBJECT`); nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize value of type `java.util.ArrayList<cn.com.sinosoft.entity.Enclosure>` from Object value (token `JsonToken.START_OBJECT`)\n at [Source: (org.springframework.util.StreamUtils$NonClosingInputStream); line: 3, column: 22] (through reference chain: cn.com.sinosoft.entity.dto.EnclosureUploadDTO[\"enclosureList\"])",
    
        "data": null
    
    }

通过错误提示最后一句话

(through reference chain: cn.com.sinosoft.entity.dto.EnclosureUploadDTO\[\\"enclosureList\\"\])"

大概能看出是我这个集合数据传参方式不对

正确的方式应该为：

{
        "id": "1590593194199277570",
        "enclosureList": [{
            "name": "soft.pdf",
            "enclosureName": "soft.pdf",
            "enclosureType": 21,
            "enclosureId": "1591262808073314362",
            "url": "www.baidu.com"
        }]
    }

因为enclosureList是一个集合，要在后面加上中括号

好了，这就是我解决以上错误的方法。。。

[d0ecbaf4400d41c0b712bb5870a4baa2.png]: https://img-blog.csdnimg.cn/d0ecbaf4400d41c0b712bb5870a4baa2.png

“JSON parse error: Cannot deserialize value of type `java.util.ArrayList＜XXX＞` from Object value ...

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