结构领域的资本 [英] Capitals in struct fields

问题描述

我正在使用该库来访问CouchDB(具体来说为cloudant)"github.com/mikebell-org/go-couchdb"，但我注意到了一个问题.

I'm using this library to access CouchDB (cloudant to be specific) "github.com/mikebell-org/go-couchdb" and I've noticed a problem.

当我将文件添加到数据库并传递结构时，仅添加以大写字母开头的结构字段.

When I go to add a file to the database and pass in a struct, only the fields of the struct which started with a capital letter get added.

例如

type Person struct {
    name string
    Age  int
}

func main() {
    db, _ := couchdb.Database(host, database, username, password)
    joe := Person{
        name: "mike",
        Age:  190,
    }
    m, _ := db.PostDocument(joe)
}

在这种情况下，只有年龄"字段被更新并插入到我的数据库中.

In this case, only the "age" field got updated and inserted into my database.

在另一种情况下，我也注意到了这个问题-当我这样做时:

I've noticed this problem in another case also - when I'm doing something like this :

type Sample struct {
    Name string
    age  int 
}


joe := Sample{
    Name: "xx",
    age:  23,
}

byt, _ := json.Marshal(joe)

post_data := strings.NewReader(string(byt))
fmt.Println(post_data)

在这种情况下，只有名称会被打印出来:

in this case, only Name would be printed out :

output : &{{"Name":"xx"} 0 -1}

这是为什么?并且如果我想使用一个小写的字段并将其放入数据库中，那有可能吗?

Why is this? and If I would like to have a field with a lowercase and be inside the database, is that possible?

推荐答案

这是因为仅导出以大写字母开头的字段，或者换句话说，在curent程序包之外(在这种情况下，在json程序包中) ).

This is because only fields starting with a capital letter are exported, or in other words visible outside the curent package (and in the json package in this case).

以下是与此相关的规范的一部分: http://golang.org/ref/spec#Exported_identifiers

Here is the part of the specifications refering to this: http://golang.org/ref/spec#Exported_identifiers

不过，您可以使用所谓的标签"来解组不以大写字母开头的json字段.对于json包，这是要使用的语法:

Still, you can unmarshall json fields that do no start with a capital letters using what is called "tags". With the json package, this is the syntax to use:

type Sample struct {
    Name string `json:"name"`
    Age  int    `json:"age"`
}

有关此信息，请参见文档.

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