How to pass a slice element to a function - go

Question

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?

Answer 1

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.