Simple way to paginate Gorm result. paginate is compatible with net/http and fasthttp. This library also supports many frameworks are based on net/http or fasthttp.
Table Of Contents
Installation
go get -u github.com/dikhimartin/paginate
Configuration
var db *gorm.DB = ...
var req *http.Request = ...
// or
// var req *fasthttp.Request
model := db.Where("id > ?", 1).Model(&Article{})
pg := paginate.New()
page := pg.Response(model, req, &[]Article{})
// or
page := pg.With(model).Request(req).Response(&[]Article{})
log.Println(page.Total)
log.Println(page.Items)
log.Println(page.First)
log.Println(page.Last)
you can customize config with paginate.Config
struct.
pg := paginate.New(&paginate.Config{
DefaultSize: 50,
})
see more about customize default configuration.
Note that Response
was marked as a deprecated function. Please use With
instead.
Old: pg.Response(model, req, &[]Article{})
,
New: pg.With(model).Request(req).Response(&[]Article{})
Paginate using http request
example paging, sorting and filtering:
http://localhost:3000/?size=10&page=0&sort=-name
produces:
SELECT * FROM user ORDER BY name DESC LIMIT 10 OFFSET 0
JSON
response:
{
// result items
"items": [
{
"id": 1,
"name": "john",
"age": 20
}
],
"page": 0, // current selected page
"size": 10, // current limit or size per page
"max_page": 0, // maximum page
"total_pages": 1, // total pages
"total": 1, // total matches including next page
"visible": 1, // total visible on current page
"last": true, // if response is first page
"first": true // if response is last page
}
http://localhost:3000/?size=10&page=1&sort=-name,id
produces:
SELECT * FROM user ORDER BY name DESC, id ASC LIMIT 10 OFFSET 10
http://localhost:3000/?filters=["name","john"]
produces:
SELECT * FROM user WHERE name = 'john' LIMIT 10 OFFSET 0
http://localhost:3000/?filters=["name","like","john"]
produces:
SELECT * FROM user WHERE name LIKE '%john%' LIMIT 10 OFFSET 0
http://localhost:3000/?filters=["age","between",[20, 25]]
produces:
SELECT * FROM user WHERE ( age BETWEEN 20 AND 25 ) LIMIT 10 OFFSET 0
http://localhost:3000/?filters=[["name","like","john%25"],["OR"],["age","between",[20, 25]]]
produces:
SELECT * FROM user WHERE (
(name LIKE '%john\%%' ESCAPE '\') OR (age BETWEEN (20 AND 25))
) LIMIT 10 OFFSET 0
http://localhost:3000/?filters=[[["name","like","john"],["AND"],["name","not like","doe"]],["OR"],["age","between",[20, 25]]]
produces:
SELECT * FROM user WHERE (
(
(name LIKE '%john%')
AND
(name NOT LIKE '%doe%')
)
OR
(age BETWEEN (20 AND 25))
) LIMIT 10 OFFSET 0
http://localhost:3000/?filters=["name","IS NOT",null]
produces:
SELECT * FROM user WHERE name IS NOT NULL LIMIT 10 OFFSET 0
- Using
POST
method:
curl -X POST \
-H 'Content-type: application/json' \
-d '{"page":"1","size":"20","sort":"-name","filters":["name","john"]}' \
http://localhost:3000/
Example usage
NetHTTP Example
package main
import (
"github.com/dikhimartin/paginate"
...
)
func main() {
// var db *gorm.DB
pg := paginate.New()
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
model := db.Joins("User").Model(&Article{})
paginated := pg.Response(model, r, &[]Article{})
j, _ := json.Marshal(paginated)
w.Header().Set("Content-type", "application/json")
w.Write(j)
})
log.Fatal(http.ListenAndServe(":3000", nil))
}
Fasthttp Example
package main
import (
"github.com/dikhimartin/paginate"
...
)
func main() {
// var db *gorm.DB
pg := paginate.New()
fasthttp.ListenAndServe(":3000", func(ctx *fasthttp.RequestCtx) {
model := db.Joins("User").Model(&Article{})
paginated := pg.Response(model, &ctx.Request, &[]Article{})
j, _ := json.Marshal(paginated)
ctx.SetContentType("application/json")
ctx.SetBody(j)
})
}
Mux Router Example
package main
import (
"github.com/dikhimartin/paginate"
...
)
func main() {
// var db *gorm.DB
pg := paginate.New()
app := mux.NewRouter()
app.HandleFunc("/", func(w http.ResponseWriter, req *http.Request) {
model := db.Joins("User").Model(&Article{})
paginated := pg.Response(model, req, &[]Article{})
j, _ := json.Marshal(paginated)
w.Header().Set("Content-type", "application/json")
w.Write(j)
}).Methods("GET")
http.Handle("/", app)
http.ListenAndServe(":3000", nil)
}
Fiber example
package main
import (
"github.com/dikhimartin/paginate"
...
)
func main() {
// var db *gorm.DB
pg := paginate.New()
app := fiber.New()
app.Get("/", func(c *fiber.Ctx) error {
model := db.Joins("User").Model(&Article{})
return c.JSON(pg.Response(model, c.Request(), &[]Article{}))
})
app.Listen(":3000")
}
Echo example
package main
import (
"github.com/dikhimartin/paginate"
...
)
func main() {
// var db *gorm.DB
pg := paginate.New()
app := echo.New()
app.GET("/", func(c echo.Context) error {
model := db.Joins("User").Model(&Article{})
return c.JSON(200, pg.Response(model, c.Request(), &[]Article{}))
})
app.Logger.Fatal(app.Start(":3000"))
}
Gin Example
package main
import (
"github.com/dikhimartin/paginate"
...
)
func main() {
// var db *gorm.DB
pg := paginate.New()
app := gin.Default()
app.GET("/", func(c *gin.Context) {
model := db.Joins("User").Model(&Article{})
c.JSON(200, pg.Response(model, c.Request, &[]Article{}))
})
app.Run(":3000")
}
Martini Example
package main
import (
"github.com/dikhimartin/paginate"
...
)
func main() {
// var db *gorm.DB
pg := paginate.New()
app := martini.Classic()
app.Use(render.Renderer())
app.Get("/", func(req *http.Request, r render.Render) {
model := db.Joins("User").Model(&Article{})
r.JSON(200, pg.Response(model, req, &[]Article{}))
})
app.Run()
}
Beego Example
package main
import (
"github.com/dikhimartin/paginate"
...
)
func main() {
// var db *gorm.DB
pg := paginate.New()
web.Get("/", func(c *context.Context) {
model := db.Joins("User").Model(&Article{})
c.Output.JSON(
pg.Response(model, c.Request, &[]Article{}), false, false)
})
web.Run(":3000")
}
jQuery DataTable Integration
var logicalOperator = "OR"
$('#myTable').DataTable({
columns: [
{
title: "Author",
data: "user.name"
}, {
title: "Title",
data: "title"
}
],
processing: true,
serverSide: true,
ajax: {
cache: true,
url: "http://localhost:3000/articles",
dataSrc: function(json) {
json.recordsTotal = json.visible
json.recordsFiltered = json.total
return json.items
},
data: function(params) {
var custom = {
page: !params.start ? 0 : Math.round(params.start / params.length),
size: params.length
}
if (params.order.length > 0) {
var sorts = []
for (var o in params.order) {
var order = params.order[o]
if (params.columns[order.column].orderable != false) {
var sort = order.dir != 'desc' ? '' : '-'
sort += params.columns[order.column].data
sorts.push(sort)
}
}
custom.sort = sorts.join()
}
if (params.search.value) {
var columns = []
for (var c in params.columns) {
var col = params.columns[c]
if (col.searchable == false) {
continue
}
columns.push(JSON.stringify([col.data, "like", encodeURIComponent(params.search.value.toLowerCase())]))
}
custom.filters = '[' + columns.join(',["' + logicalOperator + '"],') + ']'
}
return custom
}
},
})
jQuery Select2 Integration
$('#mySelect').select2({
ajax: {
url: "http://localhost:3000/users",
processResults: function(json) {
json.items.forEach(function(item) {
item.text = item.name
})
// optional
if (json.first) json.items.unshift({id: 0, text: 'All'})
return {
results: json.items,
pagination: {
more: json.last == false
}
}
},
data: function(params) {
var filters = [
["name", "like", params.term]
]
return {
filters: params.term ? JSON.stringify(filters) : "",
sort: "name",
page: params.page && params.page - 1 ? params.page - 1 : 0
}
},
}
})
The format of filter param is a json encoded of multidimensional array.
Maximum array members is three, first index is column_name
, second index is operator
and third index is values
, you can also pass array to values.
// Format:
["column_name", "operator", "values"]
// Example:
["age", "=", 20]
// Shortcut:
["age", 20]
// Produces:
// WHERE age = 20
Single array member is known as Logical Operator.
// Example
[["age", "=", 20],["or"],["age", "=", 25]]
// Produces:
// WHERE age = 20 OR age = 25
You are allowed to send array inside a value.
["age", "between", [20, 30] ]
// Produces:
// WHERE age BETWEEN 20 AND 30
["age", "not in", [20, 21, 22, 23, 24, 25, 26, 26] ]
// Produces:
// WHERE age NOT IN(20, 21, 22, 23, 24, 25, 26, 26)
You can filter nested condition with deep array.
[
[
["age", ">", 20],
["and"]
["age", "<", 30]
],
["and"],
["name", "like", "john"],
["and"],
["name", "like", "doe"]
]
// Produces:
// WHERE ( (age > 20 AND age < 20) and name like '%john%' and name like '%doe%' )
For null
value, you can send string "null"
or null
value, (lower)
// Wrong request
[ "age", "is", NULL ]
[ "age", "is", Null ]
[ "age", "is not", NULL ]
[ "age", "is not", Null ]
// Right request
[ "age", "is", "NULL" ]
[ "age", "is", "Null" ]
[ "age", "is", "null" ]
[ "age", "is", null ]
[ "age", null ]
[ "age", "is not", "NULL" ]
[ "age", "is not", "Null" ]
[ "age", "is not", "null" ]
[ "age", "is not", null ]
Customize default configuration
You can customize the default configuration with paginate.Config
struct.
pg := paginate.New(&paginate.Config{
DefaultSize: 50,
})
Config |
Type |
Default |
Description |
Operator |
string |
OR |
Default conditional operator if no operator specified. For example
GET /user?filters=[["name","like","jo"],["age",">",20]] , produces
SELECT * FROM user where name like '%jo' OR age > 20 |
FieldWrapper |
string |
LOWER(%s) |
FieldWrapper for LIKE operator (for postgres default is: LOWER((%s)::text) ) |
DefaultSize |
int64 |
10 |
Default size or limit per page |
SmartSearch |
bool |
false |
Enable smart search (Experimental feature) |
CustomParamEnabled |
bool |
false |
Enable custom request parameter |
FieldSelectorEnabled |
bool |
false |
Enable partial response with specific fields. Comma separated per field. eg: ?fields=title,user.name |
SortParams |
[]string |
[]string{"sort"} |
if CustomParamEnabled is true , you can set the SortParams with custom parameter names. For example: []string{"sorting", "ordering", "other_alternative_param"} . The following requests will capture same result
?sorting=-name or ?ordering=-name or ?other_alternative_param=-name or ?sort=-name |
PageParams |
[]string |
[]string{"page"} |
if CustomParamEnabled is true , you can set the PageParams with custom parameter names. For example:
[]string{"number", "num", "other_alternative_param"} . The following requests will capture same result ?number=0 or ?num=0 or ?other_alternative_param=0 or ?page=0 |
SizeParams |
[]string |
[]string{"size"} |
if CustomParamEnabled is true , you can set the SizeParams with custom parameter names. For example:
[]string{"limit", "max", "other_alternative_param"} . The following requests will capture same result ?limit=50 or ?limit=50 or ?other_alternative_param=50 or ?max=50 |
OrderParams |
[]string |
[]string{"order"} |
if CustomParamEnabled is true , you can set the OrderParams with custom parameter names. For example:
[]string{"order", "direction", "other_alternative_param"} . The following requests will capture same result ?order=desc or ?direction=desc or ?other_alternative_param=desc |
FilterParams |
[]string |
[]string{"filters"} |
if CustomParamEnabled is true , you can set the FilterParams with custom parameter names. For example:
[]string{"search", "find", "other_alternative_param"} . The following requests will capture same result
?search=["name","john"] or ?find=["name","john"] or ?other_alternative_param=["name","john"] or ?filters=["name","john"] |
FieldsParams |
[]string |
[]string{"fields"} |
if FieldSelectorEnabled and CustomParamEnabled is true , you can set the FieldsParams with custom parameter names. For example:
[]string{"fields", "columns", "other_alternative_param"} . The following requests will capture same result ?fields=title,user.name or ?columns=title,user.name or ?other_alternative_param=title,user.name |
CacheAdapter |
*gocache.AdapterInterface |
nil |
the cache adapter, see more about cache config. |
Override results
You can override result with custom function.
// var db = *gorm.DB
// var httpRequest ... net/http or fasthttp instance
// Example override function
override := func(article *Article) {
if article.UserID > 0 {
article.Title = fmt.Sprintf(
"%s written by %s", article.Title, article.User.Name)
}
}
var articles []Article
model := db.Joins("User").Model(&Article{})
pg := paginate.New()
result := pg.Response(model, httpRequest, &articles)
for index := range articles {
override(&articles[index])
}
log.Println(result.Items)
Field selector
To implement a custom field selector, struct properties must have a json tag with omitempty.
// real gorm model
type User {
gorm.Model
Name string `json:"name"`
Age int64 `json:"age"`
}
// fake gorm model
type UserNullable {
ID *string `json:"id,omitempty"`
CreatedAt *time.Time `json:"created_at,omitempty"`
UpdatedAt *time.Time `json:"updated_at,omitempty"`
Name *string `json:"name,omitempty"`
Age *int64 `json:"age,omitempty"`
}
// usage
nameAndIDOnly := []string{"name","id"}
model := db.Model(&User{})
page := pg.With(model).
Request(req).
Fields(nameAndIDOnly).
Response([]&UserNullable{})
// response
{
"items": [
{
"id": 1,
"name": "John"
}
],
...
}
Dynamic field selector
If the request contains query parameter fields
(eg: ?fieilds=name,id
), then the response will show only name
and id
. To activate this feature, please set FieldSelectorEnabled
to true
.
config := paginate.Config{
FieldSelectorEnabled: true,
}
pg := paginate.New(config)
Speed up response with cache
You can speed up results without looking database directly with cache adapter. See more about cache adapter.
In memory cache
in memory cache is not recommended for production environment:
import (
"github.com/dikhimartin/gocache"
...
)
func main() {
...
adapterConfig := gocache.InMemoryCacheConfig{
ExpiresIn: 1 * time.Hour,
}
pg := paginate.New(&paginate.Config{
CacheAdapter: gocache.NewInMemoryCache(adapterConfig),
})
page := pg.With(model).
Request(req).
Cache("article"). // set cache name
Response(&[]Article{})
...
}
Disk cache
Disk cache will create a file for every single request. You can use disk cache if you don't care about inode.
import (
"github.com/dikhimartin/gocache"
...
)
func main() {
adapterConfig := gocache.DiskCacheConfig{
Directory: "/writable/path/to/my-cache-dir",
ExpiresIn: 1 * time.Hour,
}
pg := paginate.New(&paginate.Config{
CacheAdapter: gocache.NewDiskCache(adapterConfig),
})
page := pg.With(model).
Request(req).
Cache("article"). // set cache name
Response(&[]Article{})
...
}
Redis cache
Redis cache require redis client for golang.
import (
cache "github.com/dikhimartin/gocache-redis/v8"
"github.com/go-redis/redis/v8"
...
)
func main() {
client := redis.NewClient(&redis.Options{
Addr: "localhost:6379",
Password: "",
DB: 0,
})
adapterConfig := cache.RedisCacheConfig{
Client: client,
ExpiresIn: 1 * time.Hour,
}
pg := paginate.New(&paginate.Config{
CacheAdapter: cache.NewRedisCache(adapterConfig),
})
page := pg.With(model).
Request(req).
Cache("article").
Response(&[]Article{})
...
}
if your code already adopts another redis client, you can implement the redis adapter according to its version. See more about redis adapter.
Elasticsearch cache
Elasticsearch cache require official elasticsearch client for golang.
import (
cache "github.com/dikhimartin/gocache-elasticsearch/v7"
"github.com/elastic/go-elasticsearch/v7"
...
)
func main() {
config := elasticsearch.Config{
Addresses: []string{
"http://localhost:9200",
},
}
es, err := elasticsearch.NewClient(config)
if nil != err {
panic(err)
}
adapterConfig := cache.ElasticCacheConfig{
Client: es,
Index: "exampleproject",
ExpiresIn: 1 * time.Hour,
}
pg := paginate.New(&paginate.Config{
CacheAdapter: cache.NewElasticCache(adapterConfig),
})
page := pg.With(model).
Request(req).
Cache("article").
Response(&[]Article{})
...
}
if your code already adopts another elasticsearch client, you can implement the elasticsearch adapter according to its version. See more about elasticsearch adapter.
Custom cache
Create your own cache adapter by implementing gocache AdapterInterface. See more about cache adapter.
// AdapterInterface interface
type AdapterInterface interface {
// Set cache with key
Set(key string, value string) error
// Get cache by key
Get(key string) (string, error)
// IsValid check if cache is valid
IsValid(key string) bool
// Clear clear cache by key
Clear(key string) error
// ClearPrefix clear cache by key prefix
ClearPrefix(keyPrefix string) error
// Clear all cache
ClearAll() error
}
Clean up cache
Clear cache by cache name
pg.ClearCache("article")
Clear multiple cache
pg.ClearCache("cache1", "cache2", "cache3")
Clear all cache
pg.ClearAllCache()
Limitations
Paginate doesn't support has many relationship. You can make API with separated endpoints for parent and child:
GET /users
{
"items": [
{
"id": 1,
"name": "john",
"age": 20,
"addresses": [...] // doesn't support
}
],
...
}
Best practice:
GET /users
{
"items": [
{
"id": 1,
"name": "john",
"age": 20
}
],
...
}
GET /users/1/addresses
{
"items": [
{
"id": 1,
"name": "home",
"street": "home street"
"user": {
"id": 1,
"name": "john",
"age": 20
}
}
],
...
}
Paginate doesn't support for customized json or table field name.
Make sure your struct properties have same name with gorm column and json property before you expose them.
Example bad configuration:
type User struct {
gorm.Model
UserName string `gorm:"column:nickname" json:"name"`
UserAddress string `gorm:"column:user_address" json:"address"`
}
// request: GET /path/to/endpoint?sort=-name,address
// response: "items": [] with sql error (column name not found)
Best practice:
type User struct {
gorm.Model
Name string `gorm:"column:name" json:"name"`
Address string `gorm:"column:address" json:"address"`
}
License
Published under the MIT License.