2022年更新

Axios现在支持将对象自动序列化为FormData

从0.27版开始，如果请求的Content-Type报头被设置为multipart/form-data, Axios就支持将对象自动序列化为FormData对象。阅读更多

嵌套对象和文件

下面的解决方案处理嵌套对象、数组和文件。

const buildFormData = (formData: FormData, data: FormVal, parentKey?: string) => {
    if (Array.isArray(data)) {
        data.forEach((el) => {
            buildFormData(formData, el, parentKey)
        })

    } else if (typeof data === "object" && !(data instanceof File)) {
        Object.keys(data).forEach((key) => {
            buildFormData(formData, (data as FormDataNest)[key], parentKey ? `${parentKey}.${key}` : key)
        })

    } else {
        if (isNil(data)) {
            return
        }

        let value = typeof data === "boolean" || typeof data === "number" ? data.toString() : data
        formData.append(parentKey as string, value)
    }
}

export const getFormData = (data: Record<string, FormDataNest>) => {
    const formData = new FormData()

    buildFormData(formData, data)

    return formData
}

类型

type FormDataPrimitive = string | Blob | number | boolean

interface FormDataNest {
  [x: string]: FormVal
}

type FormVal = FormDataNest | FormDataPrimitive

下面是一个使用Object.entries()的简单而甜蜜的解决方案，它甚至可以处理嵌套对象。

// If this is the object you want to convert to FormData...
const item = {
    description: 'First item',
    price: 13,
    photo: File
};

const formData = new FormData();

Object.entries(item).forEach(([key, value]) => {
    formData.append(key, value);
});

// At this point, you can then pass formData to your handler method

阅读更多关于Object.entries()在这里- https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/entries

尝试JSON。函数如下所示

var postData = JSON.stringify(item);
var formData = new FormData();
formData.append("postData",postData );

如果您有一个对象，您可以轻松地创建一个FormData对象，并将该对象的名称和值附加到FormData。

你还没有发布任何代码，所以这是一个通用的例子;

var form_data = new FormData();

for ( var key in item ) {
    form_data.append(key, item[key]);
}

$.ajax({
    url         : 'http://example.com/upload.php',
    data        : form_data,
    processData : false,
    contentType : false,
    type: 'POST'
}).done(function(data){
    // do stuff
});

在MDN的文档中有更多的例子

抱歉这么晚才回答，我一直在纠结这个问题，因为Angular 2目前不支持文件上传。方法是用FormData发送一个XMLHttpRequest。我创建了一个函数来做这个。我用的是Typescript。要将其转换为Javascript只需删除数据类型声明。

/**
     * Transforms the json data into form data.
     *
     * Example:
     *
     * Input:
     * 
     * fd = new FormData();
     * dob = {
     *  name: 'phone',
     *  photos: ['myphoto.jpg', 'myotherphoto.png'],
     *  price: '615.99',
     *  color: {
     *      front: 'red',
     *      back: 'blue'
     *  },
     *  buttons: ['power', 'volup', 'voldown'],
     *  cameras: [{
     *      name: 'front',
     *      res: '5Mpx'
     *  },{
     *      name: 'back',
     *      res: '10Mpx'
     *  }]
     * };
     * Say we want to replace 'myotherphoto.png'. We'll have this 'fob'.
     * fob = {
     *  photos: [null, <File object>]
     * };
     * Say we want to wrap the object (Rails way):
     * p = 'product';
     *
     * Output:
     *
     * 'fd' object updated. Now it will have these key-values "<key>, <value>":
     *
     * product[name], phone
     * product[photos][], myphoto.jpg
     * product[photos][], <File object>
     * product[color][front], red
     * product[color][back], blue
     * product[buttons][], power
     * product[buttons][], volup
     * product[buttons][], voldown
     * product[cameras][][name], front
     * product[cameras][][res], 5Mpx
     * product[cameras][][name], back
     * product[cameras][][res], 10Mpx
     * 
     * @param {FormData}  fd  FormData object where items will be appended to.
     * @param {Object}    dob Data object where items will be read from.
     * @param {Object =   null} fob File object where items will override dob's.
     * @param {string =   ''} p Prefix. Useful for wrapping objects and necessary for internal use (as this is a recursive method).
     */
    append(fd: FormData, dob: Object, fob: Object = null, p: string = ''){
        let apnd = this.append;

        function isObj(dob, fob, p){
            if(typeof dob == "object"){
                if(!!dob && dob.constructor === Array){
                    p += '[]';
                    for(let i = 0; i < dob.length; i++){
                        let aux_fob = !!fob ? fob[i] : fob;
                        isObj(dob[i], aux_fob, p);
                    }
                } else {
                    apnd(fd, dob, fob, p);
                }
            } else {
                let value = !!fob ? fob : dob;
                fd.append(p, value);
            }
        }

        for(let prop in dob){
            let aux_p = p == '' ? prop : `${p}[${prop}]`;
            let aux_fob = !!fob ? fob[prop] : fob;
            isObj(dob[prop], aux_fob, aux_p);
        }
    }

该函数将object中的所有数据添加到FormData中

ES6版本来自@developer033:

function buildFormData(formData, data, parentKey) {
  if (data && typeof data === 'object' && !(data instanceof Date) && !(data instanceof File)) {
    Object.keys(data).forEach(key => {
      buildFormData(formData, data[key], parentKey ? `${parentKey}[${key}]` : key);
    });
  } else {
    const value = data == null ? '' : data;

    formData.append(parentKey, value);
  }
}

function jsonToFormData(data) {
  const formData = new FormData();
  
  buildFormData(formData, data);
  
  return formData;
}

const my_data = {
  num: 1,
  falseBool: false,
  trueBool: true,
  empty: '',
  und: undefined,
  nullable: null,
  date: new Date(),
  name: 'str',
  another_object: {
    name: 'my_name',
    value: 'whatever'
  },
  array: [
    {
      key1: {
        name: 'key1'
      }
    }
  ]
};

jsonToFormData(my_data)

jQuery版本:

function appendFormdata(FormData, data, name){
    name = name || '';
    if (typeof data === 'object'){
        $.each(data, function(index, value){
            if (name == ''){
                appendFormdata(FormData, value, index);
            } else {
                appendFormdata(FormData, value, name + '['+index+']');
            }
        })
    } else {
        FormData.append(name, data);
    }
}


var formData = new FormData(),
    your_object = {
        name: 'test object',
        another_object: {
            name: 'and other objects',
            value: 'whatever'
        }
    };
appendFormdata(formData, your_object);