在golang中使用json区分空字段和未设置字段.pdfVIP

在golang中使⽤json 区分空字段和未设置字段 A few weeks ago, I was working on a Golang microservice where I needed to add support for CRUD operations with JSON data. Normally, I would make a structure for the entity with all the fields defined in it along with ‘omitempty’ attribute as shown ⼏周前，我正在研究Golang微服务，需要在其中添加对使⽤JSON数据进⾏CRUD操作的⽀持。 通常，我会为实体创建⼀个结构，其中定 义了所有字段以及omitempty属性，如下所⽰ type Article struct { Id string `json:id` Name string `json:name,omitempty` Desc string `json:desc,omitempty` } Problem 问题 But this kind of representation poses a serious problem, especially for Update or Edit operations. 但是这种表⽰形式带来了严重的问题，尤其是对于Update或Edit操作。 For example, let’s say that the update request JSON looks something like this 例如，假设更新请求JSON看起来像这样 {id:1234,name:xyz,desc:} Notice the empty desc field. Now lets see how it is unmarshalled in Go 注意空的desc字段。 现在让我们看看如何在Go中将其解组 func Test_JSON1(t *testing.T) { jsonData:=`{id:1234,name:xyz,desc:}` req:=Article{} _=json.Unmarshal([]byte(jsonData),req) fmt.Printf(%+v,req) }Output: === RUN Test_JSON1 {Id:1234 Name:xyz Desc:} Here description comes as an empty string, It’s clearly visible that the client wants to set desc as an empty string and that is inferred by our program. 这⾥的描述是⼀个空字符串，很明显，客户端希望将desc设置为⼀个空字符串，这是由我们的程序推断出来的。 But what if the client does not want the change the existing value for Description, in that case, sending a big description string again is not the right thing to do, hence the JSON would look like this 但是，如果客户端不希望更改Description的现有值，在那种情况下，再次发送⼤的描述字符串是不正确的事情，因此JSON看起来像这样 {id:1234,name:xyz} Let’s unmarshal it into our structure 让我们将其解组到我们的结构中 func Test_JSON2(t *testing.T) { jsonData:=`{id:1234,name:xyz}` req:=Article{} _=json.Unmarshal([]byte(jsonData),req) fmt.Printf(%+v,req) }Output: === RUN Test_JSON2 {Id:1234 Name:xyz Desc:} Well, we still get Desc as an empty string , so how do we differe