search
HomeBackend DevelopmentGolangHow to do nested iteration

How to do nested iteration

php editor Youzi will introduce you how to perform nested iteration. Nested iteration is a technique of using another loop within a loop, which helps us deal with complex data structures or multi-dimensional arrays. When doing nested iterations, we need to pay attention to the order and conditions of the loops to ensure that each element is accessed and processed correctly. This article will explain the principles and usage of nested iteration in detail, and provide some practical examples for reference. Whether you are a beginner or an experienced developer, this article can help you better understand and apply the techniques of nested iteration. Let’s explore together!

Question content

I'm trying to develop an extension to another software that sends requests to an application written in go. In a go program (which I will now call a "program"), one purpose is to convert a json file into an iterable format. Here is an example of the json format I'm using:

{
  "name": "game-name",
  "tree": {
    "$classname": "datamodel",

    "replicatedstorage": {
      "$path": "src/replicatedstorage"
    },

    "serverscriptservice": {
      "$path": "src/serverscriptservice"
    },

    "replicatedfirst": {
      "$path": "src/replicatedfirst"
    },

    "serverstorage": {
      "$path": "src/serverstorage"
    }
  }
}

The idea is:

  • Iteration can get the "name"
  • Iteration can get "$classname"
  • For all instances with "$path" as the index, a folder will be created under the parent src folder containing the index of the parent map. For example, replicatedstorage is the name of the folder with the path src/replicatedstorage

Here is a handler function to do this:

func process(in interface{}) {
v := reflect.ValueOf(in)

    if v.Kind() == reflect.Map {
        for _, key := range v.MapKeys() {
            strct := v.MapIndex(key)
    
            index := key.Interface()
            value := reflect.ValueOf(strct.Interface())
    
            if index == "tree" {
                for _, treeKey := range value.MapKeys() {
                    treeIndex := treeKey.Interface()
    
                    fmt.Println("KEY")
                    fmt.Println(treeIndex)
    
                    if treeIndex != "$className" {
                        fmt.Println("bug")
                        fmt.Println(treeKey)
    
                        a := key.MapIndex(value) // panic serving ...: reflect: call of reflect.Value.MapIndex on string Value
                        b := reflect.ValueOf(a.Interface())
    
                        for _, key2 := range b.MapKeys() {
                            index2 := key2.Interface()
                            value2 := reflect.ValueOf(key2.Interface())
    
                            fmt.Println(index2)
                            fmt.Println(value2)
                        }
                    }
                }
            }
        }
    }

}

Comments pointed out incorrect location and content. One thing I'd also like to do is not have to stack the for loops, because that's really bad code.

Solution

The usual approach is to unmarshal into a go type that matches the data structure. The problem here is that the tree cannot be easily represented as a go type (it has a field $classname of type string, but is otherwise similar to a map with an object value containing a $path field).

Let's continue unmarshaling to interface{} as you have already done.

Use type assertions instead of reflection packages. Use Map Index to look up the value instead of looping through the keys and looking for a match.

func process(in interface{}) error {
    top, ok := in.(map[string]interface{})
    if !ok {
        return errors.New("expected object at top level")
    }
    tree, ok := top["tree"].(map[string]interface{})
    if !ok {
        return errors.New(".tree not found")
    }
    name, ok := top["name"]
    if !ok {
        return errors.New(".name not found")
    }
    className, ok := tree["$className"].(string)
    if !ok {
        return errors.New(".tree.$className not found")
    }
    for k, v := range tree {
        thing, ok := v.(map[string]interface{})
        if !ok {
            continue
        }
        path, ok := thing["$path"].(string)
        if !ok {
            continue
        }
        fmt.Println(name, className, k, path)
    }
    return nil
}

https://www.php.cn/link/8642785813491d703d517ddd00944054

The above is the detailed content of How to do nested iteration. For more information, please follow other related articles on the PHP Chinese website!

Statement
This article is reproduced at:stackoverflow. If there is any infringement, please contact admin@php.cn delete
How do you use the pprof tool to analyze Go performance?How do you use the pprof tool to analyze Go performance?Mar 21, 2025 pm 06:37 PM

The article explains how to use the pprof tool for analyzing Go performance, including enabling profiling, collecting data, and identifying common bottlenecks like CPU and memory issues.Character count: 159

How do you write unit tests in Go?How do you write unit tests in Go?Mar 21, 2025 pm 06:34 PM

The article discusses writing unit tests in Go, covering best practices, mocking techniques, and tools for efficient test management.

How do I write mock objects and stubs for testing in Go?How do I write mock objects and stubs for testing in Go?Mar 10, 2025 pm 05:38 PM

This article demonstrates creating mocks and stubs in Go for unit testing. It emphasizes using interfaces, provides examples of mock implementations, and discusses best practices like keeping mocks focused and using assertion libraries. The articl

How can I define custom type constraints for generics in Go?How can I define custom type constraints for generics in Go?Mar 10, 2025 pm 03:20 PM

This article explores Go's custom type constraints for generics. It details how interfaces define minimum type requirements for generic functions, improving type safety and code reusability. The article also discusses limitations and best practices

How can I use tracing tools to understand the execution flow of my Go applications?How can I use tracing tools to understand the execution flow of my Go applications?Mar 10, 2025 pm 05:36 PM

This article explores using tracing tools to analyze Go application execution flow. It discusses manual and automatic instrumentation techniques, comparing tools like Jaeger, Zipkin, and OpenTelemetry, and highlighting effective data visualization

Explain the purpose of Go's reflect package. When would you use reflection? What are the performance implications?Explain the purpose of Go's reflect package. When would you use reflection? What are the performance implications?Mar 25, 2025 am 11:17 AM

The article discusses Go's reflect package, used for runtime manipulation of code, beneficial for serialization, generic programming, and more. It warns of performance costs like slower execution and higher memory use, advising judicious use and best

How do you use table-driven tests in Go?How do you use table-driven tests in Go?Mar 21, 2025 pm 06:35 PM

The article discusses using table-driven tests in Go, a method that uses a table of test cases to test functions with multiple inputs and outcomes. It highlights benefits like improved readability, reduced duplication, scalability, consistency, and a

How do you specify dependencies in your go.mod file?How do you specify dependencies in your go.mod file?Mar 27, 2025 pm 07:14 PM

The article discusses managing Go module dependencies via go.mod, covering specification, updates, and conflict resolution. It emphasizes best practices like semantic versioning and regular updates.

See all articles

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

AI Hentai Generator

AI Hentai Generator

Generate AI Hentai for free.

Hot Article

Repo: How To Revive Teammates
1 months agoBy尊渡假赌尊渡假赌尊渡假赌
R.E.P.O. Energy Crystals Explained and What They Do (Yellow Crystal)
2 weeks agoBy尊渡假赌尊渡假赌尊渡假赌
Hello Kitty Island Adventure: How To Get Giant Seeds
1 months agoBy尊渡假赌尊渡假赌尊渡假赌

Hot Tools

SecLists

SecLists

SecLists is the ultimate security tester's companion. It is a collection of various types of lists that are frequently used during security assessments, all in one place. SecLists helps make security testing more efficient and productive by conveniently providing all the lists a security tester might need. List types include usernames, passwords, URLs, fuzzing payloads, sensitive data patterns, web shells, and more. The tester can simply pull this repository onto a new test machine and he will have access to every type of list he needs.

SAP NetWeaver Server Adapter for Eclipse

SAP NetWeaver Server Adapter for Eclipse

Integrate Eclipse with SAP NetWeaver application server.

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

SublimeText3 Linux new version

SublimeText3 Linux new version

SublimeText3 Linux latest version

Dreamweaver Mac version

Dreamweaver Mac version

Visual web development tools