从MongoDB在Go API中过滤显示的信息。

huangapple
go评论110阅读模式
英文:

Filtering what information is displayed from MongoDB in Go api

问题

我是Go和React的新手，我正在使用它们进行这个小项目。Go正在运行一个使用Mongodb的后端API。

我在Go中从Mongo中获取用户列表，然后将其发送到React，问题是Mongo给我返回了用户的所有字段（_id、password和username），我只想要username字段。我不明白如何过滤这些字段并阻止所有字段从Go发送到React。

Go API的JSON输出：

  1. {
  2.     "Success": true,
  3.     "Data": [
  4.         {
  5.             "_id": "6205ac3d72c15c920a424608",
  6.             "password": {
  7.                 "Subtype": 0,
  8.                 "Data": "removed for security"
  9.             },
  10.             "username": "removed for security"
  11.         },
  12.         {
  13.             "_id": "6206b44afb8b044fdba76b8f",
  14.             "password": {
  15.                 "Subtype": 0,
  16.                 "Data": "removed for security"
  17.             },
  18.             "username": "removed for security"
  19.         }
  20.     ]
  21. }

这是我指定路由的Go代码：

  1. // 路由：获取用户列表
  2. func RouteGetUsers(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
  3. 	// 设置内容类型为JSON
  4. 	w.Header().Set("Content-Type", "application/json")
  6. 	type Response struct {
  7. 		Success bool     `json:"Success"`
  8. 		Data    []bson.M `json:"Data"`
  9. 	}
  11. 	// 加载环境变量文件
  12. 	err := godotenv.Load("variables.env")
  13. 	if err != nil {
  14. 		log.Fatal("加载.env文件时出错")
  15. 	}
  17. 	// 获取Mongo DB环境变量
  18. 	uri := os.Getenv("MONGO_URI")
  19. 	if uri == "" {
  20. 		log.Fatal("您必须设置您的'MONGO_URI'环境变量。请参阅\n\t https://docs.mongodb.com/drivers/go/current/usage-examples/#environment-variable")
  21. 	}
  23. 	// 连接到Mongo数据库
  24. 	client, err := mongo.Connect(context.TODO(), options.Client().ApplyURI(uri))
  25. 	if err != nil {
  26. 		panic(err)
  27. 	}
  29. 	// 在函数结束时关闭数据库连接
  30. 	defer func() {
  31. 		if err := client.Disconnect(context.TODO()); err != nil {
  32. 			panic(err)
  33. 		}
  34. 	}()
  36. 	// 选择数据库名称和集合名称
  37. 	coll := client.Database("go_project1").Collection("users")
  39. 	// 查询数据库获取用户列表
  40. 	cursor, err := coll.Find(context.TODO(), bson.D{})
  41. 	// 如果没有找到文档，则发送响应并返回
  42. 	if err == mongo.ErrNoDocuments {
  43. 		fmt.Printf("未找到文档")
  44. 		return
  45. 	}
  47. 	// 设置一个变量用于存储数据库结果
  48. 	var results []bson.M
  50. 	// 将所有数据库结果发送到results变量
  51. 	if err = cursor.All(context.TODO(), &results); err != nil {
  52. 		panic(err)
  53. 	}
  55. 	// 使用Response结构设置一个变量
  56. 	response := Response{
  57. 		Success: true,
  58. 		Data:    results,
  59. 	}
  61. 	// 转换为JSON
  62. 	responseJson, err := json.Marshal(response)
  63. 	if err != nil {
  64. 		fmt.Println(err)
  65. 	}
  67. 	// 以JSON格式向用户发送成功响应
  68. 	fmt.Fprintf(w, "%s\n", responseJson)
  69. }
英文:

I am new to Go and React, both of which I am using for this mini project. Go is running a backend api using Mongodb.

I am fetching the user list from Mongo in Go, and then sending that to React, problem is Mongo is giving me all of the fields for the user (_id, password, and username), I only want username. I am not understanding how I can filter this and prevent all fields from being sent from Go to React.

JSON Output from Go API:

  1. {
  2.     "Success": true,
  3.     "Data": [
  4.         {
  5.             "_id": "6205ac3d72c15c920a424608",
  6.             "password": {
  7.                 "Subtype": 0,
  8.                 "Data": "removed for security"
  9.             },
  10.             "username": "removed for security"
  11.         },
  12.         {
  13.             "_id": "6206b44afb8b044fdba76b8f",
  14.             "password": {
  15.                 "Subtype": 0,
  16.                 "Data": "removed for security"
  17.             },
  18.             "username": "removed for security"
  19.         }
  20.     ]
  21. }

Here is my Go code for the specified route:

  1. // Route: Get Users, for getting a list of users
  2. func RouteGetUsers(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
  3. 	// Set content-type to JSON
  4. 	w.Header().Set("Content-Type", "application/json")
  6. 	type Response struct {
  7. 		Success bool     `json:"Success"`
  8. 		Data    []bson.M `json:"Data"`
  9. 	}
  11. 	// Load the env file
  12. 	err := godotenv.Load("variables.env")
  13. 	if err != nil {
  14. 		log.Fatal("Error loading .env file")
  15. 	}
  17. 	// Get Mongo DB environment variable
  18. 	uri := os.Getenv("MONGO_URI")
  19. 	if uri == "" {
  20. 		log.Fatal("You must set your 'MONGO_URI' environmental variable. See\n\t https://docs.mongodb.com/drivers/go/current/usage-examples/#environment-variable")
  21. 	}
  23. 	// Connect to Mongo Database
  24. 	client, err := mongo.Connect(context.TODO(), options.Client().ApplyURI(uri))
  25. 	if err != nil {
  26. 		panic(err)
  27. 	}
  29. 	// Close the database connection at the end of the function
  30. 	defer func() {
  31. 		if err := client.Disconnect(context.TODO()); err != nil {
  32. 			panic(err)
  33. 		}
  34. 	}()
  36. 	// Select the database name and collection name
  37. 	coll := client.Database("go_project1").Collection("users")
  39. 	// Query the database for the user list
  40. 	cursor, err := coll.Find(context.TODO(), bson.D{})
  41. 	// If no documents were found, send a response and return
  42. 	if err == mongo.ErrNoDocuments {
  43. 		fmt.Printf("No documents were found")
  44. 		return
  45. 	}
  47. 	// Setup a variable for the database results
  48. 	var results []bson.M
  50. 	// Send all database results to results variable
  51. 	if err = cursor.All(context.TODO(), &results); err != nil {
  52. 		panic(err)
  53. 	}
  55. 	// Setup a variable with the ResponseStandard struct
  56. 	response := Response{
  57. 		Success: true,
  58. 		Data:    results,
  59. 	}
  61. 	// Marshal into JSON
  62. 	responseJson, err := json.Marshal(response)
  63. 	if err != nil {
  64. 		fmt.Println(err)
  65. 	}
  67. 	// Send success response to user in JSON
  68. 	fmt.Fprintf(w, "%s\n", responseJson)
  69. }

答案1

得分: 1

使用投影选项：

  1. opts := options.Find().SetProjection(bson.D{{"username", 1}})
  2. cursor, err := coll.Find(context.TODO(), bson.D{}, opts)

作为第二种方法：声明一个包含你想要的字段的类型，并将其提取到该类型中。

  1. type Data struct {
  2.    Username string `bson:"username" json:"username"`
  3. }
  5. ...
  7. var data []Data
  8. if err = cursor.All(context.TODO(), &data); err != nil { ...
  10. ...
  12. var response = struct {
  13.     Success bool     `json:"Success"`
  14.     Data    []Data   `json:"Data"`
  15. }{
  16.     true,
  17.     data,
  18. }
  19. responseJson, err := json.Marshal(response)
  20. ...

第三种方法：过滤问题中的映射：

  1. for _, result := range results {
  2.     for k := range result {
  3.        if k != "username" {
  4.           delete(result, k)
  5.        }
  6.     }
  7. }
英文:

Use the projection option:

  1. opts := options.Find().SetProjection(bson.D{{"username", 1}})
  2. cursor, err := coll.Find(context.TODO(), bson.D{}, opts)

As second approach: Declare a type with the fields you want, and fetch to that type.

  1. type Data struct {
  2.    Username string `bson:"username" json:"username"`
  3. }
  5. ...
  7. var data []Data
  8. if err = cursor.All(context.TODO(), &data); err != nil { ...
  10. ...
  12. var response = struct {
  13.     Success bool     `json:"Success"`
  14.     Data    []Data   `json:"Data"`
  15. }{
  16.     true,
  17.     data,
  18. }
  19. responseJson, err := json.Marshal(response)
  20. ...

A third approach: Filter the maps in the question:

  1. for _, result := range results {
  2.     for k := range result {
  3.        if k != "username" {
  4.           delete(result, k)
  5.        }
  6.     }
  7. }

huangapple
  • 本文由 发表于 2022年2月19日 02:55:15
  • 转载请务必保留本文链接：https://go.coder-hub.com/71178546.html
  • go
  • mongodb
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