Go语言XML反序列化：处理自定义日期格式的time.Time字段

type Unmarshaler interface {
    UnmarshalXML(d *Decoder, start StartElement) error
}

package main

import (
    "encoding/xml"
    "fmt"
    "time"
)

// Transaction 示例结构体，包含需要自定义日期解析的字段
type Transaction struct {
    Id              int64                  `xml:"sequencenumber"`
    ReferenceNumber string                 `xml:"ourref"`
    Description     string                 `xml:"description"`
    Type            string                 `xml:"type"`
    CustomerID      string                 `xml:"namecode"`
    DateEntered     CustomTime             `xml:"enterdate"` // 使用自定义的CustomTime类型
    Gross           float64                `xml:"gross"`
    Container       TransactionDetailContainer `xml:"subfile"`
}

// TransactionDetailContainer 嵌套结构体示例
type TransactionDetailContainer struct {
    Details []string `xml:"detail"`
}

// CustomTime 自定义时间类型，用于处理非标准日期格式的XML反序列化
type CustomTime struct {
    time.Time
}

// UnmarshalXML 为CustomTime实现xml.Unmarshaler接口
func (c *CustomTime) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
    // 定义预期的日期格式字符串。
    // "20060102" 是Go语言中 time.Parse 函数用于表示 "yyyymmdd" 格式的特殊布局。
    // 2006代表年，01代表月，02代表日。
    const shortForm = "20060102" 

    var v string
    // 解码XML元素的内容到字符串变量v中
    err := d.DecodeElement(&v, &start)
    if err != nil {
        return fmt.Errorf("failed to decode XML element to string: %w", err)
    }

    // 使用time.Parse函数将字符串v按照shortForm格式解析为time.Time
    parsedTime, err := time.Parse(shortForm, v)
    if err != nil {
        return fmt.Errorf("failed to parse date string '%s' with format '%s': %w", v, shortForm, err)
    }

    // 将解析后的time.Time赋值给CustomTime结构体中嵌入的time.Time字段
    *c = CustomTime{parsedTime}
    return nil
}

package main

import (
    "encoding/xml"
    "fmt"
    "time"
)

// CustomTime 自定义时间类型，用于处理非标准日期格式的XML反序列化
type CustomTime struct {
    time.Time
}

// UnmarshalXML 为CustomTime实现xml.Unmarshaler接口
func (c *CustomTime) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
    const shortForm = "20060102" // "yyyymmdd" 格式的Go语言布局字符串

    var v string
    err := d.DecodeElement(&v, &start)
    if err != nil {
        return fmt.Errorf("failed to decode XML element to string: %w", err)
    }

    parsedTime, err := time.Parse(shortForm, v)
    if err != nil {
        return fmt.Errorf("failed to parse date string '%s' with format '%s': %w", v, shortForm, err)
    }

    *c = CustomTime{parsedTime}
    return nil
}

// Transaction 示例结构体
type Transaction struct {
    XMLName         xml.Name               `xml:"transaction"` // 明确指定根元素名称
    Id              int64                  `xml:"sequencenumber"`
    ReferenceNumber string                 `xml:"ourref"`
    Description     string                 `xml:"description"`
    Type            string                 `xml:"type"`
    CustomerID      string                 `xml:"namecode"`
    DateEntered     CustomTime             `xml:"enterdate"` // 使用自定义的CustomTime类型
    Gross           float64                `xml:"gross"`
    Container       TransactionDetailContainer `xml:"subfile"`
}

// TransactionDetailContainer 嵌套结构体示例
type TransactionDetailContainer struct {
    Details []string `xml:"detail"`
}

func main() {
    // 模拟的XML数据，其中日期格式为"yyyymmdd"
    xmlData := `
    <transaction>
        <sequencenumber>12345</sequencenumber>
        <ourref>REF-001</ourref>
        <description>Sample Transaction</description>
        <type>SALE</type>
        <namecode>CUST001</namecode>
        <enterdate>20231026</enterdate> 
        <gross>99.99</gross>
        <subfile>
            <detail>Item A</detail>
            <detail>Item B</detail>
        </subfile>
    </transaction>`

    var transaction Transaction
    err := xml.Unmarshal([]byte(xmlData), &transaction)
    if err != nil {
        fmt.Printf("Error unmarshaling XML: %v\n", err)
        return
    }

    fmt.Printf("Transaction ID: %d\n", transaction.Id)
    fmt.Printf("Reference Number: %s\n", transaction.ReferenceNumber)
    fmt.Printf("Description: %s\n", transaction.Description)
    fmt.Printf("Date Entered: %s (Parsed Time: %s)\n", 
                transaction.DateEntered.Format("2006-01-02"), // 格式化输出，验证解析结果
                transaction.DateEntered.Time) 
    fmt.Printf("Gross Amount: %.2f\n", transaction.Gross)
    fmt.Printf("Container Details: %v\n", transaction.Container.Details)

    // 验证日期类型和值
    fmt.Printf("Type of DateEntered: %T\n", transaction.DateEntered)
    fmt.Printf("Is DateEntered a zero value? %v\n", transaction.DateEntered.IsZero())
}

type UnmarshalerAttr interface {
    UnmarshalXMLAttr(attr xml.Attr) error
}