文件上传

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原文：https://gobuffalo.io/documentation/guides/file-uploads/

File Uploads 文件上传

Since 0.10.3 自 0.10.3 起

Buffalo allows for the easily handling of files uploaded from a form. Storing those files, such as to disk or S3, is up to you the end developer: Buffalo just gives you easy access to the file from the request.

Buffalo 允许轻松处理从表单上传的文件。存储这些文件（例如，存储到磁盘或 S3）由您作为最终开发者决定：Buffalo 只让您可以轻松地从请求中访问文件。

Configuring the Form 配置表单

The f.FileTag form helper can be used to quickly add a file element to the form. When using this the enctype of the form is automatically switched to be multipart/form-data.

f.FileTag 表单帮助器可用于快速向表单添加文件元素。使用此表单时，表单的 enctype 会自动切换为 multipart/form-data 。

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<%= form_for(widget, {action: widgetsPath(), method: "POST"}) { %>
  <%= f.InputTag("Name") %>
  <%= f.FileTag("MyFile") %>
  <button class="btn btn-success" role="submit">Save</button>
  <a href="<%= widgetsPath() %>" class="btn btn-warning" data-confirm="Are you sure?">Cancel</a>
<% } %>

Accessing a Form File 访问表单文件

In the buffalo.Context the c.File takes a string, the name of the form file parameter and will return a binding.File that can be used to easily retrieve a file from the from.

在 buffalo.Context 中， c.File 采用一个字符串，即表单文件参数的名称，并将返回一个 binding.File ，可用于轻松地从表单中检索文件。

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func SomeHandler(c buffalo.Context) error {
  // ...
  f, err := c.File("someFile")
  if err != nil {
    return errors.WithStack(err)
  }
  // ...
}

Binding to a Struct 绑定到结构

The c.Bind allows form elements to be bound to a struct, but it can also attach uploaded files to the struct. To do this, the type of the struct attribute must be a binding.File type.

c.Bind 允许将表单元素绑定到结构，但它还可以将上传的文件附加到结构。为此，结构属性的类型必须是 binding.File 类型。

In the example below you can see a model, which is configured to have a MyFile attribute that is of type binding.File. There is an AfterCreate callback on this example model that saves the file to disk after the model has been successfully saved to the database.

在下面的示例中，您可以看到一个模型，该模型被配置为具有类型为 binding.File 的 MyFile 属性。此示例模型上有一个 AfterCreate 回调，该回调在模型成功保存到数据库后将文件保存到磁盘。

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// models/widget.go
type Widget struct {
  ID        uuid.UUID    `json:"id" db:"id"`
  CreatedAt time.Time    `json:"created_at" db:"created_at"`
  UpdatedAt time.Time    `json:"updated_at" db:"updated_at"`
  Name      string       `json:"name" db:"name"`
  MyFile    binding.File `db:"-" form:"someFile"`
}

func (w *Widget) AfterCreate(tx *pop.Connection) error {
  if !w.MyFile.Valid() {
    return nil
  }
  dir := filepath.Join(".", "uploads")
  if err := os.MkdirAll(dir, 0755); err != nil {
    return errors.WithStack(err)
  }
  f, err := os.Create(filepath.Join(dir, w.MyFile.Filename))
  if err != nil {
    return errors.WithStack(err)
  }
  defer f.Close()
  _, err = io.Copy(f, w.MyFile)
  return err
}

Note: The MyFile attribute is not being saved to the database because of the db:"-" struct tag.

注意：由于 db:"-" 结构标记， MyFile 属性未保存到数据库。

Testing File Uploads 测试文件上传 # HTTP 测试库（包含在 Buffalo 用于测试的包中）已更新，其中包括两个新函数：和。

The HTTP testing library, github.com/gobuffalo/httptest (which is included in the github.com/gobuffalo/suite package that Buffalo uses for testing) has been updated to include two new functions: MultiPartPost and MultiPartPut.

这些方法的工作方式与 github.com/gobuffalo/httptest 和 github.com/gobuffalo/suite 方法相同，但它们提交多部分表单，并且可以接受要上传的文件。

These methods work just like the Post and Put methods, but instead they submit a multipart form, and can accept files for upload.

与 Post 和 Put 一样，和将结构或映射作为第一个参数：这相当于您要发布的 HTML 表单。这些方法采用一个可变的第二个参数。

Like Post and Put, MultiPartPost and MultiPartPut, take a struct, or map, as the first argument: this is the equivalent of the HTML form you would post. The methods take a variadic second argument, httptest.File.

Post 需要表单参数的名称 Put ；文件的名称 MultiPartPost ；以及 MultiPartPut ，大概是您要上传的文件。

A httptest.File requires the name of the form parameter, ParamName; the name of the file, FileName; and an io.Reader, presumably the file you want to upload.

models/widgets.go

actions/widgets_test.go

actions/widgets.go