Rest Partial Response (aka Field Selection) Pattern middleware for Gin. This gin middleware allows you to select a subset of fields to be returned from your endpoints.

e.g. Imagine that you have the following rest endpoint that returns an user with the fields, id, name, surname, age, address:

/users/1

{
 "id": 1,
 "name": "John",
 "surname": "Doe",
 "age": 18,
 "address": {
   "street": "mystreet",
   "city": "mycity",
   "country": "mycountry",
   "zipcode": "1111"
 }
}

We can call the endpoint and, with the query parameter fields, filter out the fields that we are interested:

/users/1?fields=name,surname

{
 "name": "John",
 "surname": "Doe"
}

• Run the command:

go get -u -d github.com/manuelarte/milogo

• Add milogo middleware

r := gin.Default()
r.Use(Milogo())

• Call your endpoints adding the query parameter fields with the fields you want to filter:

/users/1?fields=name,surname

• Support for multiple fields filtering.

/users/1?fields=name,surname

{
 "name": "John",
 "surname": "Doe"
}

• Support for arrays

/users?fields=name

[
  {
    "name": "John"
  }
]

• Support for nested jsons.

/users/1?fields=name,surname,address(street,zipcode)

{
 "name": "John",
 "surname": "Doe",
 "address": {
   "street": "mystreet",
   "zipcode": "myzipcode"
 }
}

• Support for wrapped json.

/users/1?fields=name

{
 "data": {
    "name": "John"
 }
}

• Middleware applied to route groups with different configuration

Milogo middleware, as any other gin middleware, can be applied to different route groups with different configurations.

Feel free to create a PR or suggest improvements or ideas.