Merge pull request #1 from enverbisevac/eb/pagination

[FEAT] add pagination support

.golangci.yaml

@@ -55,6 +55,23 @@ linters-settings:
       - name: exported
         arguments:
           - disableStutteringCheck
+  tagliatelle:
+    # Check the struck tag name case.
+    case:
+      # Use the struct field name to check the name of the struct tag.
+      # Default: false
+      use-field-name: true
+      # `camel` is used for `json` and `yaml` (can be overridden)
+      # Default: {}
+      rules:
+        # Any struct tag type can be used.
+        # Support string case: `camel`, `pascal`, `kebab`, `snake`, `goCamel`, `goPascal`, `goKebab`, `goSnake`, `upper`, `lower`
+        json: snake
+        yaml: snake
+        xml: snake
+        bson: snake
+        avro: snake
+        mapstructure: snake
 
 linters:
   enable-all: true

README.md

@@ -80,6 +80,24 @@ func createUser(w http.ResponseWriter, r *http.Request) {
 	render.Render(w, r, user)
 }
 
+func dumbLoader(limit, offset int, total *int) []User {
+	*total = 100
+	return []User{
+		{
+			"Enver",
+		},
+		{
+			"Joe",
+		},
+	}
+}
+
+func listUsers(w http.ResponseWriter, r *http.Request) {
+	pagination := render.PaginationFromRequest(r)
+	data := dumbLoader(pagination.Size(), pagination.Page(), &pagination.Total)
+	pagination.Render(w, r, data)
+}
+
 func errorHandler(w http.ResponseWriter, r *http.Request) {
 	render.Error(w, r, render.ErrNotFound)
 }
@@ -94,7 +112,7 @@ func main() {
 
 ## API Reference
 
-#### Bind request body to data type `v`
+### Bind request body to data type `v`
 
 ```go
   func Bind(r *http.Request, v interface{}) error
@@ -107,7 +125,7 @@ func main() {
 
 error will be returned if binding fails
 
-#### Render responses based on request `r` headers
+### Render responses based on request `r` headers
 
 ```go
   func Render(w http.ResponseWriter, r *http.Request, v interface{}, params ...interface{})
@@ -120,7 +138,7 @@ error will be returned if binding fails
 | `v`       | `interface{}`         | **Required**. Pointer to variable.                  |
 | `params`  | `...interface{}`      | Variadic number of params. (int/string/http.Header) |
 
-#### Render error response and status code based on request `r` headers
+### Render error response and status code based on request `r` headers
 
 ```go
   func Error(w http.ResponseWriter, r *http.Request, err error, params ...interface{})
@@ -133,7 +151,7 @@ error will be returned if binding fails
 | `err`     | `error`.              | **Required**. Error value.                          |
 | `params`  | `...interface{}`      | Variadic number of params. (int/string/http.Header) |
 
-#### Params variadic function parameter
+### Params variadic function parameter
 
 `params` can be found in almost any function. Param type can be string, http.Header or integer.
 Integer value represent status code. String or http.header are just for response headers.
@@ -150,7 +168,7 @@ render.Render(w, v, http.Header{
 }, http.StatusOK)
 ```
 
-#### Integrate 3rd party JSON/XML lib
+### Integrate 3rd party JSON/XML lib
 
 in this example we will replace standard encoder with goccy/go-json.
 
@@ -175,7 +193,47 @@ func init() {
 }
 ```
 
-#### Other functions
+### Pagination
+
+pagination API function `PaginationFromRequest` accepts single parameter of type \*http.Request
+and returns `Pagination` object.
+
+```go
+pagination := render.PaginationFromRequest(r)
+```
+
+pagination struct contains several read only fields:
+
+```go
+type Pagination struct {
+	page  int
+	size  int
+	prev  int
+	next  int
+	last  int
+	Total int
+}
+```
+
+only field you can modify is Total field. Query values are mapped to pagination object:
+
+```
+http://localhost:3000/users?page=1&per_page=10
+```
+
+then you can process your input pagination data:
+
+```go
+data := loadUsers(pagination.Size(), pagination.Page(), &pagination.Total)
+```
+
+when we have data then we can render output:
+
+```go
+pagination.Render(w, r, data)
+```
+
+### Other API functions
 
 ```go
 func Blob(w http.ResponseWriter, v []byte, params ...interface{})

error_test.go

@@ -24,6 +24,7 @@ import (
 	"errors"
 	"fmt"
 	"net/http"
+	"net/url"
 	"testing"
 
 	"github.com/enverbisevac/render"
@@ -36,6 +37,15 @@ func TestError(t *testing.T) {
 		header http.Header
 	)
 
+	req := func() *http.Request {
+		return &http.Request{
+			URL: &url.URL{},
+			Header: http.Header{
+				render.AcceptHeader: []string{render.ApplicationJSON},
+			},
+		}
+	}
+
 	jsonEncoder := func(msg string) []byte {
 		resErr := render.ErrorResponse{
 			Message: msg,
@@ -78,12 +88,8 @@ func TestError(t *testing.T) {
 		{
 			name: "default error 500 - Internal Server Error",
 			args: args{
-				w: writer,
-				r: &http.Request{
-					Header: http.Header{
-						render.AcceptHeader: []string{render.ApplicationJSON},
-					},
-				},
+				w:   writer,
+				r:   req(),
 				err: errors.New("some error"),
 			},
 			body:   jsonEncoder("some error"),
@@ -92,12 +98,8 @@ func TestError(t *testing.T) {
 		{
 			name: "default mapped error 404 - file not found",
 			args: args{
-				w: writer,
-				r: &http.Request{
-					Header: http.Header{
-						render.AcceptHeader: []string{render.ApplicationJSON},
-					},
-				},
+				w:   writer,
+				r:   req(),
 				err: fmt.Errorf("file %s %w", "demo.txt", render.ErrNotFound),
 			},
 			body:   jsonEncoder(fmt.Sprintf("file %s %v", "demo.txt", render.ErrNotFound)),
@@ -106,12 +108,8 @@ func TestError(t *testing.T) {
 		{
 			name: "set optional param to BadRequest status",
 			args: args{
-				w: writer,
-				r: &http.Request{
-					Header: http.Header{
-						render.AcceptHeader: []string{render.ApplicationJSON},
-					},
-				},
+				w:      writer,
+				r:      req(),
 				err:    errors.New("bad input data"),
 				params: []interface{}{http.StatusBadRequest},
 			},
@@ -122,11 +120,7 @@ func TestError(t *testing.T) {
 			name: "provide http error",
 			args: args{
 				w: writer,
-				r: &http.Request{
-					Header: http.Header{
-						render.AcceptHeader: []string{render.ApplicationJSON},
-					},
-				},
+				r: req(),
 				err: &render.HTTPError{
 					Err:    errors.New("conflict data"),
 					Status: http.StatusConflict,
@@ -139,11 +133,7 @@ func TestError(t *testing.T) {
 			name: "provide map error, http error and param status should return param status",
 			args: args{
 				w: writer,
-				r: &http.Request{
-					Header: http.Header{
-						render.AcceptHeader: []string{render.ApplicationJSON},
-					},
-				},
+				r: req(),
 				err: &render.HTTPError{
 					Err:    render.ErrForbidden,
 					Status: http.StatusBadGateway,

examples/getting_started/main.go

@@ -31,6 +31,10 @@ type User struct {
 	Name string `json:"name"`
 }
 
+func init() {
+	render.PaginationInHeader = false
+}
+
 func helloHandler(w http.ResponseWriter, r *http.Request) {
 	paths := strings.Split(r.URL.Path, "/")
 	name := paths[len(paths)-1]
@@ -49,6 +53,24 @@ func createUser(w http.ResponseWriter, r *http.Request) {
 	render.Render(w, r, user)
 }
 
+func dumbLoader(limit, offset int, total *int) []User {
+	*total = 100
+	return []User{
+		{
+			"Enver",
+		},
+		{
+			"Joe",
+		},
+	}
+}
+
+func listUsers(w http.ResponseWriter, r *http.Request) {
+	pagination := render.PaginationFromRequest(r)
+	data := dumbLoader(pagination.Size(), pagination.Page(), &pagination.Total)
+	pagination.Render(w, r, data)
+}
+
 func errorHandler(w http.ResponseWriter, r *http.Request) {
 	render.Error(w, r, render.ErrNotFound)
 }
@@ -78,6 +100,7 @@ func errorHandler4(w http.ResponseWriter, r *http.Request) {
 func main() {
 	http.HandleFunc("/hello/", helloHandler)
 	http.HandleFunc("/create", createUser)
+	http.HandleFunc("/users", listUsers)
 	http.HandleFunc("/error", errorHandler)
 	http.HandleFunc("/error1", errorHandler1)
 	http.HandleFunc("/error2", errorHandler2)