apigogo-structtag

How do I get a specific api by it's name and then get it's ID from this "Apis" list of structs?


type Apis struct {
    Items []struct {
        ID                    string `json:"id"`
        Name                  string `json:"name"`
        Description           string `json:"description"`
        CreatedDate           int    `json:"createdDate"`
        APIKeySource          string `json:"apiKeySource"`
        EndpointConfiguration struct {
            Types []string `json:"types"`
        } `json:"endpointConfiguration"`
    } `json:"items"`
}

This the struct I have defined to store the APIs i get in json format. How do I get a specific API by its name and then get it's ID. For example lets say, apiname == Shopping and i want Shopping API's ID assigned to id variable.

ps : I'm new to golang and a well explained answer will be very much appreciated. Thanks guys


Solution

  • In your case Items is slice of custom structs, so you have to perform search over loop, like this:

    package main
    
    import (
        "encoding/json"
        "fmt"
    )
    
    type Apis struct {
        Items []struct {
            ID                    string `json:"id"`
            Name                  string `json:"name"`
            Description           string `json:"description"`
            CreatedDate           int    `json:"createdDate"`
            APIKeySource          string `json:"apiKeySource"`
            EndpointConfiguration struct {
                Types []string `json:"types"`
            } `json:"endpointConfiguration"`
        } `json:"items"`
    }
    
    func main() {
        // Some JSON example:
        jsonStr := `{"items": [{"id":"1","name":"foo"},{"id":"2","name":"bar"}]}`
    
        // Unmarshal from JSON into Apis struct.
        apis := Apis{}
        err := json.Unmarshal([]byte(jsonStr), &apis)
        if err != nil {
            // error handling
        }
    
        // Actual search:
        nameToFind := "bar"
        for _, item := range apis.Items {
            if item.Name == nameToFind {
                fmt.Printf("found: %+v", item.ID)
                break
            }
        }
    }
    

    It would be better to have map of custom structs instead of slice, so you could to do something like this:

    package main
    
    import (
        "encoding/json"
        "fmt"
    )
    
    type Apis struct {
        Items map[string]struct {
            ID                    string `json:"id"`
            Name                  string `json:"name"`
            Description           string `json:"description"`
            CreatedDate           int    `json:"createdDate"`
            APIKeySource          string `json:"apiKeySource"`
            EndpointConfiguration struct {
                Types []string `json:"types"`
            } `json:"endpointConfiguration"`
        } `json:"items"`
    }
    
    func main() {
        // Some JSON example:
        jsonStr := `{"items": {"foo":{"id":"1","name":"foo"},"bar":{"id":"2","name":"bar"}}}`
    
        // Unmarshal from JSON into Apis struct.
        apis := Apis{}
        err := json.Unmarshal([]byte(jsonStr), &apis)
        if err != nil {
            // error handling
        }
    
        // Actual search:
        nameToFind := "bar"
        item, found := apis.Items[nameToFind]
        if !found {
            fmt.Printf("item not found")
        }
        fmt.Printf("found: %+v", item)
    }
    

    IMPORTANT: with slice you complexity of algorithm will be O(n) with map - O(1) which is way better (it's best what possible).