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Fixed pagination issues. Added more tests on pagination and sorts. #42

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Sep 20, 2019
Merged

Fixed pagination issues. Added more tests on pagination and sorts. #42

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f15b4ba
Fixed pagination issues. Added more tests on pagination and sorts.
kucjac Sep 20, 2019
17b8b9f
Minor godoc fixes. Import form fixes.
kucjac Sep 20, 2019
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66 changes: 49 additions & 17 deletions query/pagination.go
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Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,7 @@ import (
"github.com/neuronlabs/neuron-core/log"
)

// Pagination constants
// Pagination defined constants used for formatting the query.
const (
// ParamPage is a JSON API query parameter used as for pagination.
ParamPage = "page"
Expand Down Expand Up @@ -39,6 +39,24 @@ const (
PageNumberPagination
)

// NewPaginationLimitOffset creates new Limit Offset pagination for given 'limit' and 'offset'.
func NewPaginationLimitOffset(limit, offset int64) (*Pagination, error) {
pagination := &Pagination{Type: LimitOffsetPagination, Size: limit, Offset: offset}
if err := pagination.IsValid(); err != nil {
return nil, err
}
return pagination, nil
}

// NewPaginationNumberSize sets the pagination of the type PageNumberSize with the page 'number' and page 'size'.
func NewPaginationNumberSize(number, size int64) (*Pagination, error) {
pagination := &Pagination{Size: size, Offset: number, Type: PageNumberPagination}
if err := pagination.IsValid(); err != nil {
return nil, err
}
return pagination, nil
}

// Pagination defines the query limits and offsets.
// It defines the maximum size (Limit) as well as an offset at which
// the query should start.
Expand Down Expand Up @@ -79,7 +97,7 @@ func (p *Pagination) First() (*Pagination, error) {
return first, nil
}

// FormatQuery formats the pagination for the url query.
// FormatQuery formats the pagination for the url query with respect to JSONAPI specification.
func (p *Pagination) FormatQuery(q ...url.Values) url.Values {
var query url.Values
if len(q) != 0 {
Expand Down Expand Up @@ -178,7 +196,7 @@ func (p *Pagination) IsValid() error {
return p.checkValues()
}

// IsZero checks if the pagination is already set.
// IsZero checks if the pagination is zero valued.
func (p *Pagination) IsZero() bool {
return p.Size == 0 && p.Offset == 0
}
Expand All @@ -199,14 +217,25 @@ func (p *Pagination) Last(total int64) (*Pagination, error) {
var last *Pagination
switch p.Type {
case LimitOffsetPagination:
offset := total - p.Size
// in case when total size is lower then the pagination size set the offset to 0
if offset < 0 {
offset = 0
var offset int64

// check if the last page is not partial
if partialSize := p.Offset % p.Size; partialSize != 0 {
lastFull := (total - partialSize) / p.Size
offset = lastFull*p.Size + partialSize
} else {
// the last should be total/p.Size - (10-3)/2 = 3
// 3 * size = 3 * 2 = 6
offset = total - p.Size
// in case when total size is lower then the pagination size set the offset to 0
if offset < 0 {
offset = 0
}
}
if offset == p.Offset {
return p, nil
}
// the offset should be total / p.Size
last = &Pagination{Size: p.Size, Offset: offset, Type: LimitOffsetPagination}
case PageNumberPagination:
// divide total number of instances by the page size.
Expand All @@ -215,9 +244,9 @@ func (p *Pagination) Last(total int64) (*Pagination, error) {
// pageSize - 10
// computedPageNumber = 52/10 = 5
pageNumber := total / p.Size
if pageNumber == 0 {
// in case when 'total' < pageSize the pageNumber = 1
pageNumber = 1
if total%p.Size != 0 || pageNumber == 0 {
// total % p.Size = 52 % 10 = 2
pageNumber++
}
last = &Pagination{Size: p.Size, Offset: pageNumber, Type: PageNumberPagination}
default:
Expand Down Expand Up @@ -246,7 +275,7 @@ func (p *Pagination) Next(total int64) (*Pagination, error) {
// in example:
// total 52; p.Offset = 50; p.Size = 10
// the next offset would be 60 which overflows possible total values.
if offset > total {
if offset >= total {
return p, nil
}
next = &Pagination{Offset: offset, Size: p.Size, Type: LimitOffsetPagination}
Expand All @@ -256,10 +285,13 @@ func (p *Pagination) Next(total int64) (*Pagination, error) {
// in example:
// total: 52; pageNumber: 6; pageSize: 10;
// nextTotal = pageNumber * pageSize = 60
if p.Size*(p.Offset) > total {
// 50 - (10 * 4+1) <= 0 ?
//
nextPageNumber := p.Offset + 1
if total-(p.Size*(nextPageNumber)) <= 0 {
return p, nil
}
next = &Pagination{Offset: p.Offset + 1, Size: p.Size, Type: PageNumberPagination}
next = &Pagination{Offset: nextPageNumber, Size: p.Size, Type: PageNumberPagination}
default:
return nil, errors.NewDet(class.QueryPaginationType, "invalid pagination type")
}
Expand All @@ -280,12 +312,12 @@ func (p *Pagination) Previous() (*Pagination, error) {
if p.Offset == 0 {
return p, nil
}
offset := p.Offset - p.Size
if offset < 0 {
return p, nil
if p.Offset < p.Size {
prev = &Pagination{Offset: 0, Size: p.Offset, Type: LimitOffsetPagination}
return prev, nil
}
// keep the same size but change the offset
prev = &Pagination{Offset: offset, Size: p.Size, Type: LimitOffsetPagination}
prev = &Pagination{Offset: p.Offset - p.Size, Size: p.Size, Type: LimitOffsetPagination}
case PageNumberPagination:
if p.Offset <= 1 {
return p, nil
Expand Down
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