How to pass a slice element to a function

I'm in the process of cleaning some code up and am trying to pass a slice value which is a struct to a function.

My struct looks like this:

type GetRecipesPaginatedResponse struct {
	Total       int         `json:"total"`
	PerPage     int         `json:"per_page"`
	CurrentPage int         `json:"current_page"`
	LastPage    int         `json:"last_page"`
	NextPageURL string      `json:"next_page_url"`
	PrevPageURL interface{} `json:"prev_page_url"`
	From        int         `json:"from"`
	To          int         `json:"to"`
	Data        []struct {
		ID               int       `json:"id"`
		ParentRecipeID   int       `json:"parent_recipe_id"`
		UserID           int       `json:"user_id"`
		Name             string    `json:"name"`
		Description      string    `json:"description"`
		IsActive         bool      `json:"is_active"`
		IsPublic         bool      `json:"is_public"`
		CreatedAt        time.Time `json:"created_at"`
		UpdatedAt        time.Time `json:"updated_at"`    		
		BjcpStyle struct {
			SubCategoryID   string `json:"sub_category_id"`
			CategoryName    string `json:"category_name"`
			SubCategoryName string `json:"sub_category_name"`
		} `json:"bjcp_style"`
		UnitType struct {
			ID   int    `json:"id"`
			Name string `json:"name"`
		} `json:"unit_type"`
	} `json:"data"`
}

In my code, I fetch some JSON data from an API and get a response back that contains about 100 items in the Data slice.

I am then looping over each item in the Data slice and processing them.

As an example, it looks something like this:

for page := 1; page < 3; page++ {
	newRecipes := getFromRecipesEndpoint(page, latestTimeStamp) //this returns an instance of GetRecipesPaginatedResponse

	for _, newRecipe := range newRecipes.Data {

		if rowExists(db, "SELECT id from community_recipes WHERE id=@id", sql.Named("id", newRecipe.ID)) {
			insertIntoRecipes(db, true, newRecipe)
		} else {
			insertIntoRecipes(db, false, newRecipe)
		}
	}
}

So I am trying to pass the instance of a recipe to the insertIntoRecipes function, which looks like this:

func insertIntoRecipes(db *sql.DB, exists bool, newRecipe GetRecipesPaginatedResponse.Data) {
	if exists {
		//update the existing record in the DB
        //perform some other updates with the information
	} else {
		//insert a new record into the DB
        //insert some other information using this information
	}
}

When I run this, I get the error:

> GetRecipesPaginatedResponse.Data undefined (type GetRecipesPaginatedResponse has no method Data)

I can tell that the issue is to do with how I am trying to pass the newRecipe to the insertIntoRecipes function, newRecipe GetRecipesPaginatedResponse.Data, however I am not quite sure how to pass it in and declare the right variable type.

To pass an item inside the Data slice to a function, when I am looping over each item of the Data slice, how do I do that?

You cannot reference the anonymous type of the Data field using a field selector. The fix is to declare a named type for the Data field:

type GetRecipesPaginatedResponse struct {
    ...
    Data        []DataItem
    ...
}

type DataItem struct {
    ID               int       `json:"id"`
    ParentRecipeID   int       `json:"parent_recipe_id"`
    UserID           int       `json:"user_id"`
    Name             string    `json:"name"`
    ...
}

Use it like this:

func insertIntoRecipes(db *sql.DB, exists bool, newRecipe DataItem) {
    ...
}

There's probably a better name for DataItem.