feat(Uploader): use before read promise resolved value (#5813)

src/uploader/README.md

@@ -140,7 +140,10 @@ export default {
           Toast('Please upload an image in jpg format');
           reject();
         } else {
-          resolve();
+          let img = new File(["foo"], "bar.jpg", {
+            type: "image/jpeg",
+          });
+          resolve(img);
         }
       });
     }

src/uploader/README.zh-CN.md

@@ -133,9 +133,9 @@ export default {
 </van-uploader>
 ```
 
-### 上传前校验
+### 上传前自定义处理
 
-通过传入`beforeRead`函数可以在上传前进行校验，返回`true`表示校验通过，返回`false`表示校验失败。支持返回`Promise`进行异步校验
+通过传入`beforeRead`函数可以在上传前进行校验，返回`true`表示校验通过，返回`false`表示校验失败。支持返回`Promise`对 file 对象进行自定义处理，例如压缩图片。
 
 ```html
 <van-uploader :before-read="beforeRead" />
@@ -161,7 +161,10 @@ export default {
           Toast('请上传 jpg 格式图片');
           reject();
         } else {
-          resolve();
+          let img = new File(["foo"], "bar.jpg", {
+            type: "image/jpeg",
+          });
+          resolve(img);
         }
       });
     }

src/uploader/index.js

@@ -113,8 +113,12 @@ export default createComponent({
 
         if (isPromise(response)) {
           response
-            .then(() => {
-              this.readFile(files);
+            .then(data => {
+              if (data) {
+                this.readFile(data);
+              } else {
+                this.readFile(files);
+              }
             })
             .catch(this.resetInput);
 

src/uploader/test/index.spec.js

@@ -118,7 +118,7 @@ it('before read return promise and resolve', async () => {
     propsData: {
       beforeRead: () =>
         new Promise(resolve => {
-          resolve();
+          resolve(file);
         }),
       afterRead,
     },
@@ -130,6 +130,25 @@ it('before read return promise and resolve', async () => {
   expect(afterRead).toHaveBeenCalledTimes(1);
 });
 
+it('before read return promise and resolve no value', async () => {
+  const afterRead = jest.fn();
+  const wrapper = mount(Uploader, {
+    propsData: {
+      beforeRead: () =>
+        new Promise(resolve => {
+          resolve();
+        }),
+      afterRead,
+    },
+  });
+
+  const input = wrapper.find('input');
+  wrapper.vm.onChange(file);
+  await later();
+  expect(afterRead).toHaveBeenCalledTimes(1);
+  expect(input.element.value).toEqual('');
+});
+
 it('before read return promise and reject', async () => {
   const afterRead = jest.fn();
   const wrapper = mount(Uploader, {
@@ -143,9 +162,9 @@ it('before read return promise and reject', async () => {
   });
 
   const input = wrapper.find('input');
+  wrapper.vm.onChange(file);
 
   await later();
-  wrapper.vm.onChange(file);
   expect(afterRead).toHaveBeenCalledTimes(0);
   expect(input.element.value).toEqual('');
 });