How can I improve this nesting logic to make it work properly and improve performance

php Xiaobian Yuzai, you may have encountered problems with nested logic when writing code, causing the code to not work properly or have low performance. To improve this problem, there are several key points to consider. First, you can revisit your logical structure to see if you can simplify or restructure your code to reduce the level of nesting. Secondly, you can consider using appropriate data structures and algorithms to optimize your code. Also, make sure your code does not duplicate calculations or redundant operations to improve performance. Finally, perform appropriate testing and debugging to ensure your code works properly under various circumstances. Through these methods, you can improve nested logic and improve the performance of your code.

Question content

I have a database containing comments, each comment has an ID and a parent ID. The goal is just to place each comment with a parent ID under its parent comment in an efficient manner.

I originally used a recursive function to search the parent annotation in the arranged array, but the performance was terrible. I refactored to use pointers to track the parent, which works almost perfectly, but it seems like the last comment to be processed is always excluded from the output.

In the example below, "comment 1" should be a child of "comment 11", but it is not included in the output at all.

package main

import (
  "encoding/json"
  "fmt"
)

// Comment from Database
type Comment struct {
  ID       string `json:"id""`
  ParentID string `json:"pid"`
  Text     string `json:"text"`
}

// NestedComment output
type NestedComment struct {
  Comment
  Children []NestedComment `json:"children,omitempty"`
}

func main() {
  // Some comment data from DB
  jsondata := `[{"id":"f1c3a838-f4b4-4ebd-bb1b-d3e4c0dce27d","pid":"6a162b3f-9341-46e9-95f7-dedc6cd06868","text":"comment 1"},{"id":"131cf4bb-1971-43a2-992f-2cbb042a4184","pid":"","text":"comment 2"},{"id":"4c93a789-ecab-4173-954c-b039cd3a9e17","pid":"131cf4bb-1971-43a2-992f-2cbb042a4184","text":"comment 3"},{"id":"c7974b6d-67e1-47d0-84fa-c78d51682df2","pid":"131cf4bb-1971-43a2-992f-2cbb042a4184","text":"comment 4"},{"id":"386c4439-4596-47c1-99bf-cb479055fe5a","pid":"","text":"comment 5"},{"id":"5ef0816e-ea13-4a7e-8009-e67ee08ef906","pid":"386c4439-4596-47c1-99bf-cb479055fe5a","text":"comment 6"},{"id":"96b0a536-602b-4f3f-a352-020f22cdfb18","pid":"","text":"comment 7"},{"id":"d0f11e98-deea-4fd5-becb-8f406ebcae83","pid":"96b0a536-602b-4f3f-a352-020f22cdfb18","text":"comment 8"},{"id":"bad87461-3cbf-4ecb-a8c7-36876b57d652","pid":"","text":"comment 9"},{"id":"e3ee6f90-495f-4348-9c29-bd6e15ec3b39","pid":"bad87461-3cbf-4ecb-a8c7-36876b57d652","text":"comment 10"},{"id":"6a162b3f-9341-46e9-95f7-dedc6cd06868","pid":"","text":"comment 11"},{"id":"041c7c2d-0688-491e-b6cd-899eac95bd3d","pid":"","text":"comment 12"},{"id":"5acdf3ff-345b-47a5-bd66-a6687a1441b7","pid":"041c7c2d-0688-491e-b6cd-899eac95bd3d","text":"comment 13"},{"id":"aaee2ae5-7e3a-4435-a094-83bf6b77abfb","pid":"","text":"comment 14"},{"id":"6108b28c-a7af-4c5a-a38c-c22db0d34b31","pid":"aaee2ae5-7e3a-4435-a094-83bf6b77abfb","text":"comment 15"},{"id":"1736393e-95b0-4f5d-a149-50fe52c28350","pid":"","text":"comment 16"},{"id":"b646f202-17aa-4af9-b8dc-c1d8ff3529ac","pid":"1736393e-95b0-4f5d-a149-50fe52c28350","text":"comment 17"},{"id":"a8827b1d-fdbc-41c2-bdb5-38e8b308dedc","pid":"b646f202-17aa-4af9-b8dc-c1d8ff3529ac","text":"comment 18"},{"id":"76e49597-6039-4cb5-a595-556ccc2e3c12","pid":"a8827b1d-fdbc-41c2-bdb5-38e8b308dedc","text":"comment 19"},{"id":"07dc4b90-65d3-4f75-8351-457305988235","pid":"76e49597-6039-4cb5-a595-556ccc2e3c12","text":"comment 20"},{"id":"2d4e838b-82df-4ca0-bf9b-f1dfb99d6763","pid":"07dc4b90-65d3-4f75-8351-457305988235","text":"comment 21"},{"id":"617c1760-0dca-409c-af2a-c614f0530e07","pid":"","text":"comment 22"},{"id":"712c0b7e-a9e4-40fd-ab78-c39b483b1435","pid":"617c1760-0dca-409c-af2a-c614f0530e07","text":"comment 23"},{"id":"e325094c-886e-42c9-bd59-fdd7a189b384","pid":"","text":"comment 24"},{"id":"f3b8b0f9-edef-4ee6-9555-42e8595f854c","pid":"e325094c-886e-42c9-bd59-fdd7a189b384","text":"comment 25"},{"id":"6e09a231-a2ee-4aa1-a898-57695e6fe153","pid":"","text":"comment 26"},{"id":"63e629d6-c0f9-4b36-ad96-e0c47cf8bb4e","pid":"6e09a231-a2ee-4aa1-a898-57695e6fe153","text":"comment 27"},{"id":"d7b698f1-8757-46db-a6e6-5141a481b42b","pid":"","text":"comment 28"},{"id":"a7e3d522-553c-44f1-befa-047bd94f0e59","pid":"","text":"comment 29"},{"id":"fe78ce24-c2c8-4d00-b96d-8b8be9ce0f06","pid":"","text":"comment 30"},{"id":"fabdccb5-a024-4476-bd51-7d55fb685c42","pid":"","text":"comment 31"},{"id":"608d0693-6e43-46a0-9e54-107da6adb109","pid":"fabdccb5-a024-4476-bd51-7d55fb685c42","text":"comment 32"}]`

  var comments []Comment

  err := json.Unmarshal([]byte(jsondata), &comments)
  if err != nil {
    panic(err)
  }

  arranged := ArrangeComments(comments, len(comments))

  arrangedjson, _ := json.MarshalIndent(arranged, "", "  ")

  fmt.Println(string(arrangedjson))
  fmt.Println("comments", len(comments), "arranged", recursiveCount(arranged))
}

func recursiveCount(arranged []NestedComment) int {
    count := len(arranged)
    for _, item := range arranged {
        count += recursiveCount(item.Children)
    }
    return count
}

// Nesting function -------------------------------------------------------------------------

func ArrangeComments(queue []Comment, count int) []NestedComment {
  var arranged []NestedComment

  // using pointers over a recursive search
  var refs []*NestedComment

  // some comments are orphaned, se we need a bail out
  tries := 0
  maxTries := 5
  prevPlacedLen := 0

  // IDs of placed comments
  var placed []string

  // while count is greater then length of placed
countloop:
  for count > len(placed) {
    // loop through queue
  queueloop:
    for _, item := range queue {

      // skip if already placed
      if len(placed) > 0 {
        for _, id := range placed {
          if id == item.ID {
            continue queueloop
          }
        }
      }

      // if parent is nil, add to arranged
      if item.ParentID == "" {
        arranged = append(arranged, NestedComment{
          Comment: item,
        })
        refs = append(refs, &arranged[len(arranged)-1])
        placed = append(placed, item.ID)
      } else {
        // if parent is not nil, loop through refs and add to children
      refloop:
        for _, ref := range refs {
          if ref.ID == item.ParentID {
            ref.Children = append(ref.Children, NestedComment{Comment: item})
            refs = append(refs, &ref.Children[len(ref.Children)-1])
            placed = append(placed, item.ID)
            break refloop
          }
        }
      }
    }

    // if no comments were placed, bail out after x tries
    if len(placed) == prevPlacedLen {
      if tries >= maxTries {
        break countloop
      }
      tries++
      break
    }

    prevPlacedLen = len(placed)
  }

  return arranged
}

Update; This got me closer, but not able to nest some deeper nested comments. The strange thing is that it produces different output every time it is run:

func ArrangeComments(comments []Comment) []NestedComment {
    // Map to hold references to NestedComment by their ID
    queue := make(map[string]*NestedComment)

    // Result slice
    var result []NestedComment

    // First, create all NestedComments and store references in the map
    for _, comment := range comments {
        nc := &NestedComment{Comment: comment}
        queue[comment.ID] = nc
    }

    // Second, loop through the map and add children to their parents
    for _, comment := range queue {
        if comment.ParentID != "" {
            parent := queue[comment.Comment.ParentID]
            if parent != nil {
                parent.Children = append(parent.Children, *comment)
            }
        }
    }

    // Third, loop through the map and add all root comments to the result slice
    for _, comment := range queue {
        if comment.ParentID == "" {
            result = append(result, *comment)
        }
    }

    return result
}

Update; I quickly wrote a JavaScript implementation that produces the correct results given the same sample data, but I can't figure out why this JS code works but the Go code doesn't.

const datajson = `[{"id":"f1c3a838-f4b4-4ebd-bb1b-d3e4c0dce27d","pid":"6a162b3f-9341-46e9-95f7-dedc6cd06868","text":"comment 1"},{"id":"131cf4bb-1971-43a2-992f-2cbb042a4184","pid":"","text":"comment 2"},{"id":"4c93a789-ecab-4173-954c-b039cd3a9e17","pid":"131cf4bb-1971-43a2-992f-2cbb042a4184","text":"comment 3"},{"id":"c7974b6d-67e1-47d0-84fa-c78d51682df2","pid":"131cf4bb-1971-43a2-992f-2cbb042a4184","text":"comment 4"},{"id":"386c4439-4596-47c1-99bf-cb479055fe5a","pid":"","text":"comment 5"},{"id":"5ef0816e-ea13-4a7e-8009-e67ee08ef906","pid":"386c4439-4596-47c1-99bf-cb479055fe5a","text":"comment 6"},{"id":"96b0a536-602b-4f3f-a352-020f22cdfb18","pid":"","text":"comment 7"},{"id":"d0f11e98-deea-4fd5-becb-8f406ebcae83","pid":"96b0a536-602b-4f3f-a352-020f22cdfb18","text":"comment 8"},{"id":"bad87461-3cbf-4ecb-a8c7-36876b57d652","pid":"","text":"comment 9"},{"id":"e3ee6f90-495f-4348-9c29-bd6e15ec3b39","pid":"bad87461-3cbf-4ecb-a8c7-36876b57d652","text":"comment 10"},{"id":"6a162b3f-9341-46e9-95f7-dedc6cd06868","pid":"","text":"comment 11"},{"id":"041c7c2d-0688-491e-b6cd-899eac95bd3d","pid":"","text":"comment 12"},{"id":"5acdf3ff-345b-47a5-bd66-a6687a1441b7","pid":"041c7c2d-0688-491e-b6cd-899eac95bd3d","text":"comment 13"},{"id":"aaee2ae5-7e3a-4435-a094-83bf6b77abfb","pid":"","text":"comment 14"},{"id":"6108b28c-a7af-4c5a-a38c-c22db0d34b31","pid":"aaee2ae5-7e3a-4435-a094-83bf6b77abfb","text":"comment 15"},{"id":"1736393e-95b0-4f5d-a149-50fe52c28350","pid":"","text":"comment 16"},{"id":"b646f202-17aa-4af9-b8dc-c1d8ff3529ac","pid":"1736393e-95b0-4f5d-a149-50fe52c28350","text":"comment 17"},{"id":"a8827b1d-fdbc-41c2-bdb5-38e8b308dedc","pid":"b646f202-17aa-4af9-b8dc-c1d8ff3529ac","text":"comment 18"},{"id":"76e49597-6039-4cb5-a595-556ccc2e3c12","pid":"a8827b1d-fdbc-41c2-bdb5-38e8b308dedc","text":"comment 19"},{"id":"07dc4b90-65d3-4f75-8351-457305988235","pid":"76e49597-6039-4cb5-a595-556ccc2e3c12","text":"comment 20"},{"id":"2d4e838b-82df-4ca0-bf9b-f1dfb99d6763","pid":"07dc4b90-65d3-4f75-8351-457305988235","text":"comment 21"},{"id":"617c1760-0dca-409c-af2a-c614f0530e07","pid":"","text":"comment 22"},{"id":"712c0b7e-a9e4-40fd-ab78-c39b483b1435","pid":"617c1760-0dca-409c-af2a-c614f0530e07","text":"comment 23"},{"id":"e325094c-886e-42c9-bd59-fdd7a189b384","pid":"","text":"comment 24"},{"id":"f3b8b0f9-edef-4ee6-9555-42e8595f854c","pid":"e325094c-886e-42c9-bd59-fdd7a189b384","text":"comment 25"},{"id":"6e09a231-a2ee-4aa1-a898-57695e6fe153","pid":"","text":"comment 26"},{"id":"63e629d6-c0f9-4b36-ad96-e0c47cf8bb4e","pid":"6e09a231-a2ee-4aa1-a898-57695e6fe153","text":"comment 27"},{"id":"d7b698f1-8757-46db-a6e6-5141a481b42b","pid":"","text":"comment 28"},{"id":"a7e3d522-553c-44f1-befa-047bd94f0e59","pid":"","text":"comment 29"},{"id":"fe78ce24-c2c8-4d00-b96d-8b8be9ce0f06","pid":"","text":"comment 30"},{"id":"fabdccb5-a024-4476-bd51-7d55fb685c42","pid":"","text":"comment 31"},{"id":"608d0693-6e43-46a0-9e54-107da6adb109","pid":"fabdccb5-a024-4476-bd51-7d55fb685c42","text":"comment 32"}]`

const queue = JSON.parse(datajson)

const result = []

const queueMap = new Map(queue.map(item => [item.id, item]))

for (const item of queue) {
  if (item.pid !== '') {
    const parent = queueMap.get(item.pid)
    if (parent) {
      if (!parent.children) {
        parent.children = []
      }
      parent.children.push(item)
    }
  }
}

for (const [_, value] of queueMap) {
  if (value.pid === '') {
    result.push(value)
  }
}

function recursiveCount(res) {
  let count = res.length
  res.forEach(item => {
    if (item.children) {
      count += recursiveCount(item.children)
    }
  });
  return count
}


console.log(JSON.stringify(result, null, 2))
console.log("comments", queue.length, "arranged", recursiveCount(result))

Runnable Go example: https://gist.github.com/dlford/9e66069cfc7fb9afc649c5e3dc650083

Runnable JS example: https://gist.github.com/dlford/f6f4a383a99f65659895ed51d1a4b651

Go code output (see count at bottom): https://gist.github.com/dlford/302c4db939c21d15132848368caa01ec

JS code output (see count at bottom): https://gist.github.com/dlford/60ab49d0466c957c7745059022e27e09

Solution

The problem is in NestedComment The Children also needs to be stored as a pointer.

Working example:

package main

import (
    "encoding/json"
    "fmt"
)

// Comment from Database
type Comment struct {
    ID       string `json:"id"`
    ParentID string `json:"pid"`
    Text     string `json:"text"`
}

// NestedComment output
type NestedComment struct {
    Comment
    Children []*NestedComment `json:"children,omitempty"`
}

func main() {
    // Some comment data from DB
    jsondata := `[{"id":"f1c3a838-f4b4-4ebd-bb1b-d3e4c0dce27d","pid":"6a162b3f-9341-46e9-95f7-dedc6cd06868","text":"comment 1"},{"id":"131cf4bb-1971-43a2-992f-2cbb042a4184","pid":"","text":"comment 2"},{"id":"4c93a789-ecab-4173-954c-b039cd3a9e17","pid":"131cf4bb-1971-43a2-992f-2cbb042a4184","text":"comment 3"},{"id":"c7974b6d-67e1-47d0-84fa-c78d51682df2","pid":"131cf4bb-1971-43a2-992f-2cbb042a4184","text":"comment 4"},{"id":"386c4439-4596-47c1-99bf-cb479055fe5a","pid":"","text":"comment 5"},{"id":"5ef0816e-ea13-4a7e-8009-e67ee08ef906","pid":"386c4439-4596-47c1-99bf-cb479055fe5a","text":"comment 6"},{"id":"96b0a536-602b-4f3f-a352-020f22cdfb18","pid":"","text":"comment 7"},{"id":"d0f11e98-deea-4fd5-becb-8f406ebcae83","pid":"96b0a536-602b-4f3f-a352-020f22cdfb18","text":"comment 8"},{"id":"bad87461-3cbf-4ecb-a8c7-36876b57d652","pid":"","text":"comment 9"},{"id":"e3ee6f90-495f-4348-9c29-bd6e15ec3b39","pid":"bad87461-3cbf-4ecb-a8c7-36876b57d652","text":"comment 10"},{"id":"6a162b3f-9341-46e9-95f7-dedc6cd06868","pid":"","text":"comment 11"},{"id":"041c7c2d-0688-491e-b6cd-899eac95bd3d","pid":"","text":"comment 12"},{"id":"5acdf3ff-345b-47a5-bd66-a6687a1441b7","pid":"041c7c2d-0688-491e-b6cd-899eac95bd3d","text":"comment 13"},{"id":"aaee2ae5-7e3a-4435-a094-83bf6b77abfb","pid":"","text":"comment 14"},{"id":"6108b28c-a7af-4c5a-a38c-c22db0d34b31","pid":"aaee2ae5-7e3a-4435-a094-83bf6b77abfb","text":"comment 15"},{"id":"1736393e-95b0-4f5d-a149-50fe52c28350","pid":"","text":"comment 16"},{"id":"b646f202-17aa-4af9-b8dc-c1d8ff3529ac","pid":"1736393e-95b0-4f5d-a149-50fe52c28350","text":"comment 17"},{"id":"a8827b1d-fdbc-41c2-bdb5-38e8b308dedc","pid":"b646f202-17aa-4af9-b8dc-c1d8ff3529ac","text":"comment 18"},{"id":"76e49597-6039-4cb5-a595-556ccc2e3c12","pid":"a8827b1d-fdbc-41c2-bdb5-38e8b308dedc","text":"comment 19"},{"id":"07dc4b90-65d3-4f75-8351-457305988235","pid":"76e49597-6039-4cb5-a595-556ccc2e3c12","text":"comment 20"},{"id":"2d4e838b-82df-4ca0-bf9b-f1dfb99d6763","pid":"07dc4b90-65d3-4f75-8351-457305988235","text":"comment 21"},{"id":"617c1760-0dca-409c-af2a-c614f0530e07","pid":"","text":"comment 22"},{"id":"712c0b7e-a9e4-40fd-ab78-c39b483b1435","pid":"617c1760-0dca-409c-af2a-c614f0530e07","text":"comment 23"},{"id":"e325094c-886e-42c9-bd59-fdd7a189b384","pid":"","text":"comment 24"},{"id":"f3b8b0f9-edef-4ee6-9555-42e8595f854c","pid":"e325094c-886e-42c9-bd59-fdd7a189b384","text":"comment 25"},{"id":"6e09a231-a2ee-4aa1-a898-57695e6fe153","pid":"","text":"comment 26"},{"id":"63e629d6-c0f9-4b36-ad96-e0c47cf8bb4e","pid":"6e09a231-a2ee-4aa1-a898-57695e6fe153","text":"comment 27"},{"id":"d7b698f1-8757-46db-a6e6-5141a481b42b","pid":"","text":"comment 28"},{"id":"a7e3d522-553c-44f1-befa-047bd94f0e59","pid":"","text":"comment 29"},{"id":"fe78ce24-c2c8-4d00-b96d-8b8be9ce0f06","pid":"","text":"comment 30"},{"id":"fabdccb5-a024-4476-bd51-7d55fb685c42","pid":"","text":"comment 31"},{"id":"608d0693-6e43-46a0-9e54-107da6adb109","pid":"fabdccb5-a024-4476-bd51-7d55fb685c42","text":"comment 32"}]`

    var comments []Comment

    err := json.Unmarshal([]byte(jsondata), &comments)
    if err != nil {
        panic(err)
    }

    arranged := ArrangeComments(comments)

    arrangedjson, _ := json.MarshalIndent(arranged, "", "  ")

    fmt.Println(string(arrangedjson))
    fmt.Println("comments", len(comments), "arranged", recursiveCount(arranged))
}

func recursiveCount(arranged []*NestedComment) int {
    count := len(arranged)
    for _, item := range arranged {
        count += recursiveCount(item.Children)
    }
    return count
}

// Nesting function -------------------------------------------------------------------------

func ArrangeComments(comments []Comment) []*NestedComment {
    // Map to hold references to NestedComment by their ID
    queue := make(map[string]*NestedComment)

    // Result slice
    var result []*NestedComment

    // First, create all NestedComments and store references in the map
    for _, comment := range comments {
        nc := &NestedComment{Comment: comment}
        queue[comment.ID] = nc
    }

    // Second, loop through the map and add children to their parents
    for _, comment := range queue {
        if comment.ParentID != "" {
            parent := queue[comment.Comment.ParentID]
            if parent != nil {
                parent.Children = append(parent.Children, comment)
            }
        }
    }

    // Third, loop through the map and add all root comments to the result slice
    for _, comment := range queue {
        if comment.ParentID == "" {
            result = append(result, comment)
        }
    }

    return result
}

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