Return empty list instead of null

Question

I want to change my current function to return empty JSON list, currently it returns nil.

This is my current code:

func (s *Service) pro         


        

Answer 1

Another way to handle this is to check if the slice is nil and initialize it:

projects = ps
if projects == nil {
    projects = make([]*models.Project, 0)
}

This can be tedious if you have several structs and structs with arrays. To handle those, you can create custom marshalers or dynamically inspect fields.

Source: Arrays and JSON in Go

Answer 2

A nil slice encodes to a null JSON object. This is documented at json.Marshal():

Array and slice values encode as JSON arrays, except that []byte encodes as a base64-encoded string, and a nil slice encodes as the null JSON value.

If you want a non-null empty JSON array, use a non-nil empty Go slice.

See this example:

type Project struct {
    Name string `json:"name"`
}

enc := json.NewEncoder(os.Stdout)

var ps []*Project
enc.Encode(ps)

ps = []*Project{}
enc.Encode(ps)

Output (try it on the Go Playground):

null
[]

So in your case make sure projects is not nil, for example:

projects = ps
if projects == nil {
    projects = []*models.Project{}
}