CODEWITHSUNDEEP
gostruct
Amanda Ferrari
Amanda Ferrari

Reputation: 946

Is it possible to delete a field of a struct value at runtime?

I have the following struct:

type Record struct {
  Id     string   `json:"id"`
  ApiKey string   `json:"apiKey"`
  Body   []string `json:"body"`
  Type   string   `json:"type"`
}

Which is a Blueprint of a dynamoDB table. And I need somehow, delete the ApiKey, after using to check if the user has access to the giving record. Explaining:

I have and endpoint in my API where the user can send a id to get a item, but he needs to have access to the ID and the ApiKey (I'm using Id (uuid) + ApiKey) to create unique items.

How I'm doing:

 func getExtraction(id string, apiKey string) (Record, error) {
    svc := dynamodb.New(cfg)

    req := svc.GetItemRequest(&dynamodb.GetItemInput{
      TableName: aws.String(awsEnv.Dynamo_Table),
      Key: map[string]dynamodb.AttributeValue{
        "id": {
          S: aws.String(id),
        },
      },
    })

    result, err := req.Send()
    if err != nil {
      return Record{}, err
    }

    record := Record{}
    err = dynamodbattribute.UnmarshalMap(result.Item, &record)
    if err != nil {
      return Record{}, err
    }

    if record.ApiKey != apiKey {
      return Record{}, fmt.Errorf("item %d not found", id)
    }
    // Delete ApiKey from record
    return record, nil
  }

After checking if the ApiKey is equal to the provided apiKey, I want to delete the ApiKey from record, but unfortunately that's not possible using delete.

Thank you.

Upvotes: 7

Views: 29239

Answers (2)

Arthur Savage
Arthur Savage

Reputation: 31

  1. Created RecordShort structure without "ApiKey"
  2. Marshalin Record
  3. Unmarsaling Record to ShortRecord
type RecordShot struct {
  Id     string   `json:"id"`
  Body   []string `json:"body"`
  Type   string   `json:"type"`
}
    
record,_:=json.Marshal(Record)
json.Unmarshal([]byte(record), &RecordShot)

Upvotes: 2

SwiftD
SwiftD

Reputation: 6069

There is no way to actually edit a golang type (such as a struct) at runtime. Unfortunately you haven't really explained what you are hoping to achieve by "deleting" the APIKey field.

General approaches would be:

  1. set the APIKey field to an empty string after inspection, if you dont want to display this field when empty set the json struct tag to omitempty (e.g `json:"apiKey,omitempty"`)

  2. set the APIKey field to never Marshal into JSON ( e.g ApiKey string `json:"-"`) and you will still be able to inspect it just wont display in JSON, you could take this further by adding a custom marshal / unmarshal function to handle this in one direction or in a context dependent way

  3. copy the data to a new struct, e.g type RecordNoAPI struct without the APIKey field and return that after you have inspected the original Record

Upvotes: 28

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