How Can I Detect Duplicate Attributes in JSON Strings Using Go?

Detect Duplicate Attributes in JSON Strings with Go

How do we identify duplicate attributes within JSON strings in Go? Let's delve into a solution using JSON decoding and key value analysis.

Decoding the JSON String

We utilize the json.Decoder to traverse the JSON string. As we encounter objects, we iterate through their keys and values in search of duplicates.

Checking for Duplicates

Within the check function, we distinguish between different delimeters and handle each case separately:

• Objects ({}): We create a map to track unique keys. If a duplicate key is found, we call a user-defined dup function that can log the duplicate or return an error to terminate the traversal.
• Arrays ([]): We treat each element as an item in a slice and recursively check for duplicates within that item.

Usage Example

To demonstrate its functionality, let's define a printDup function that prints the duplicate key path and call check on a sample JSON string:

func printDup(path []string) error {
    fmt.Printf("Duplicate %s\n", strings.Join(path, "/"))
    return nil
}

...

data := `{"a": "b", "a":true,"c":["field_3 string 1","field3 string2"], "d": {"e": 1, "e": 2}}`
if err := check(json.NewDecoder(strings.NewReader(data)), nil, printDup); err != nil {
    log.Fatal(err)
}

This will output:

Duplicate a
Duplicate d/e

Handling Duplicates with Errors

Alternatively, we can generate an error on the first duplicate key encountered:

var ErrDuplicate = errors.New("duplicate")

func dupErr(path []string) error {
    return ErrDuplicate
}

...

data := `{"a": "b", "a":true,"c":["field_3 string 1","field3 string2"], "d": {"e": 1, "e": 2}}`
err := check(json.NewDecoder(strings.NewReader(data)), nil, dupErr)
if err == ErrDuplicate {
    fmt.Println("found a duplicate")
} else if err != nil {
    // some other error
    log.Fatal(err)
}

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