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url_values.go
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url_values.go
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package orm
import (
"fmt"
"net/url"
"strconv"
"strings"
"github.com/go-pg/pg/types"
)
// URLFilters is used with Query.Apply to add WHERE clauses from the URL values:
// - ?foo=bar - Where(`"foo" = 'bar'`)
// - ?foo=hello&foo=world - Where(`"foo" IN ('hello','world')`)
// - ?foo__exclude=bar - Where(`"foo" != 'bar'`)
// - ?foo__ieq=bar - Where(`"foo" ILIKE 'bar'`)
// - ?foo__match=bar - Where(`"foo" SIMILAR TO 'bar'`)
// - ?foo__gt=42 - Where(`"foo" > 42`)
// - ?foo__gte=42 - Where(`"foo" >= 42`)
// - ?foo__lt=42 - Where(`"foo" < 42`)
// - ?foo__lte=42 - Where(`"foo" <= 42`)
func URLFilters(urlValues url.Values) func(*Query) (*Query, error) {
return func(q *Query) (*Query, error) {
for fieldName, values := range urlValues {
var operation string
if i := strings.Index(fieldName, "__"); i != -1 {
fieldName, operation = fieldName[:i], fieldName[i+2:]
}
if q.model.Table().HasField(fieldName) {
q = addOperator(q, fieldName, operation, values)
}
}
return q, nil
}
}
func addOperator(q *Query, fieldName, operator string, values []string) *Query {
switch operator {
case "gt":
q = forEachValue(q, fieldName, values, "? > ?")
case "gte":
q = forEachValue(q, fieldName, values, "? >= ?")
case "lt":
q = forEachValue(q, fieldName, values, "? < ?")
case "lte":
q = forEachValue(q, fieldName, values, "? <= ?")
case "ieq":
q = forEachValue(q, fieldName, values, "? ILIKE ?")
case "match":
q = forEachValue(q, fieldName, values, "? SIMILAR TO ?")
case "exclude":
q = forAllValues(q, fieldName, values, "? != ?", "? NOT IN (?)")
case "", "include":
q = forAllValues(q, fieldName, values, "? = ?", "? IN (?)")
}
return q
}
func forEachValue(q *Query, fieldName string, values []string, queryTemplate string) *Query {
for _, value := range values {
q = q.Where(queryTemplate, types.F(fieldName), value)
}
return q
}
func forAllValues(q *Query, fieldName string, values []string, queryTemplate, queryArrayTemplate string) *Query {
if len(values) > 1 {
q = q.Where(queryArrayTemplate, types.F(fieldName), types.InSlice(values))
} else {
q = q.Where(queryTemplate, types.F(fieldName), values[0])
}
return q
}
type Pager struct {
Limit int
Offset int
// Default max limit is 1000.
MaxLimit int
// Default max offset is 1000000.
MaxOffset int
stickyErr error
}
func NewPager(values url.Values) *Pager {
p := new(Pager)
p.SetURLValues(values)
return p
}
func (p *Pager) SetURLValues(values url.Values) {
limit, err := intParam(values, "limit")
if err != nil {
p.stickyErr = err
return
}
p.Limit = limit
page, err := intParam(values, "page")
if err != nil {
p.stickyErr = err
return
}
if page > 0 {
p.SetPage(page)
}
}
func (p *Pager) maxLimit() int {
if p.MaxLimit > 0 {
return p.MaxLimit
}
return 1000
}
func (p *Pager) maxOffset() int {
if p.MaxOffset > 0 {
return p.MaxOffset
}
return 1000000
}
func (p *Pager) GetLimit() int {
const defaultLimit = 100
if p.Limit <= 0 {
return defaultLimit
}
if p.Limit > p.maxLimit() {
return p.maxLimit()
}
return p.Limit
}
func (p *Pager) GetOffset() int {
if p.Offset > p.maxOffset() {
return p.maxOffset()
}
if p.Offset > 0 {
return p.Offset
}
return 0
}
func (p *Pager) SetPage(page int) {
p.Offset = (page - 1) * p.GetLimit()
}
func (p *Pager) GetPage() int {
return (p.GetOffset() / p.GetLimit()) + 1
}
func (p *Pager) Paginate(q *Query) (*Query, error) {
if p.stickyErr != nil {
return nil, p.stickyErr
}
q = q.Limit(p.GetLimit()).
Offset(p.GetOffset())
return q, nil
}
// Pagination is used with Query.Apply to set LIMIT and OFFSET from the URL values:
// - ?limit=10 - sets q.Limit(10), max limit is 1000.
// - ?page=5 - sets q.Offset((page - 1) * limit), max offset is 1000000.
func Pagination(values url.Values) func(*Query) (*Query, error) {
return NewPager(values).Paginate
}
func intParam(urlValues url.Values, paramName string) (int, error) {
values, ok := urlValues[paramName]
if !ok {
return 0, nil
}
value, err := strconv.Atoi(values[0])
if err != nil {
return 0, fmt.Errorf("param=%s value=%s is invalid: %s", paramName, values[0], err)
}
return value, nil
}