使用Golang结构体解析JSON字符串

你能给我一些示例来说明如何完成吗。

你的JSON中BookDocuments字段的值是一个字符串数组，每个字符串本身是一个JSON对象。你需要先解析外层的JSON，然后对每个字符串元素进行二次解析。

以下是修正后的代码：

package main

import (
	"encoding/json"
	"fmt"
)

type BookDocuments struct {
	BookDocuments []string `json:"BookDocuments"`
}

type Document struct {
	BookID      string                 `json:"Book_id"`
	ID          string                 `json:"id"`
	Name        string                 `json:"name"`
	StartTime   float64                `json:"start_time"`
	EndTime     float64                `json:"end_time"`
	Origin      string                 `json:"origin"`
	Type        string                 `json:"type"`
	Namespace   string                 `json:"namespace"`
	Library     map[string]interface{} `json:"library"`
	Annotations map[string]interface{} `json:"annotations"`
}

func main() {
	jsonStr := `{
		"BookDocuments": ["{\"Book_id\":\"1-5f0171f2-000000000000000000000000\",\"id\":\"0100000000000000\",\"name\":\"words-generator-span\",\"start_time\":1593930226.651007,\"end_time\":1593930226.6520069,\"origin\":\"library::shelf::Author\",\"type\":\"sub\",\"namespace\":\"remote\",\"library\":{},\"annotations\":{\"words_generator_span_seq_num\":\"\",\"words_generator_Book_seq_num\":\"\"}}\n", "{\"Book_id\":\"1-5f0171f2-000000000000000000000000\",\"id\":\"0200000000000000\",\"name\":\"words-generator-span\",\"start_time\":1593930226.651019,\"end_time\":1593930226.652019,\"origin\":\"library::shelf::Author\",\"type\":\"sub\",\"namespace\":\"remote\",\"library\":{},\"annotations\":{\"words_generator_span_seq_num\":\"\",\"words_generator_Book_seq_num\":\"\"}}\n"]
	}`

	var wrapper BookDocuments
	err := json.Unmarshal([]byte(jsonStr), &wrapper)
	if err != nil {
		fmt.Printf("解析外层JSON失败: %v\n", err)
		return
	}

	var documents []Document
	for _, docStr := range wrapper.BookDocuments {
		var doc Document
		err := json.Unmarshal([]byte(docStr), &doc)
		if err != nil {
			fmt.Printf("解析文档失败: %v\n", err)
			continue
		}
		documents = append(documents, doc)
	}

	fmt.Printf("成功解析 %d 个文档\n", len(documents))
	for i, doc := range documents {
		fmt.Printf("文档 %d: ID=%s, Name=%s\n", i+1, doc.ID, doc.Name)
	}
}

如果你需要保持原来的结构体设计，可以使用json.RawMessage：

package main

import (
	"encoding/json"
	"fmt"
)

type BookDocuments struct {
	BookDocuments []json.RawMessage `json:"BookDocuments"`
}

type Document struct {
	BookID      string                 `json:"Book_id"`
	ID          string                 `json:"id"`
	Name        string                 `json:"name"`
	StartTime   float64                `json:"start_time"`
	EndTime     float64                `json:"end_time"`
	Origin      string                 `json:"origin"`
	Type        string                 `json:"type"`
	Namespace   string                 `json:"namespace"`
	Library     map[string]interface{} `json:"library"`
	Annotations map[string]interface{} `json:"annotations"`
}

func main() {
	jsonStr := `{
		"BookDocuments": ["{\"Book_id\":\"1-5f0171f2-000000000000000000000000\",\"id\":\"0100000000000000\",\"name\":\"words-generator-span\",\"start_time\":1593930226.651007,\"end_time\":1593930226.6520069,\"origin\":\"library::shelf::Author\",\"type\":\"sub\",\"namespace\":\"remote\",\"library\":{},\"annotations\":{\"words_generator_span_seq_num\":\"\",\"words_generator_Book_seq_num\":\"\"}}\n"]
	}`

	var wrapper BookDocuments
	err := json.Unmarshal([]byte(jsonStr), &wrapper)
	if err != nil {
		fmt.Printf("解析失败: %v\n", err)
		return
	}

	var documents []Document
	for _, rawDoc := range wrapper.BookDocuments {
		var doc Document
		err := json.Unmarshal(rawDoc, &doc)
		if err != nil {
			fmt.Printf("解析文档失败: %v\n", err)
			continue
		}
		documents = append(documents, doc)
	}

	fmt.Printf("成功解析 %d 个文档\n", len(documents))
}

主要问题：

1. BookDocuments字段的值是字符串数组，不是直接的对象数组
2. 结构体字段名需要与JSON标签完全匹配（注意大小写）
3. library字段在你的JSON中是空对象{}，所以使用map[string]interface{}更合适