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miniflux/storage/entry_pagination_builder.go
2018-08-24 21:56:39 -07:00

166 lines
4.3 KiB
Go

// Copyright 2018 Frédéric Guillot. All rights reserved.
// Use of this source code is governed by the Apache 2.0
// license that can be found in the LICENSE file.
package storage // import "miniflux.app/storage"
import (
"database/sql"
"fmt"
"strings"
"time"
"miniflux.app/model"
"miniflux.app/timer"
)
// EntryPaginationBuilder is a builder for entry prev/next queries.
type EntryPaginationBuilder struct {
store *Storage
conditions []string
args []interface{}
entryID int64
direction string
}
// WithSearchQuery adds full-text search query to the condition.
func (e *EntryPaginationBuilder) WithSearchQuery(query string) {
if query != "" {
e.conditions = append(e.conditions, fmt.Sprintf("e.document_vectors @@ plainto_tsquery($%d)", len(e.args)+1))
e.args = append(e.args, query)
}
}
// WithStarred adds starred to the condition.
func (e *EntryPaginationBuilder) WithStarred() {
e.conditions = append(e.conditions, "e.starred is true")
}
// WithFeedID adds feed_id to the condition.
func (e *EntryPaginationBuilder) WithFeedID(feedID int64) {
if feedID != 0 {
e.conditions = append(e.conditions, fmt.Sprintf("e.feed_id = $%d", len(e.args)+1))
e.args = append(e.args, feedID)
}
}
// WithCategoryID adds category_id to the condition.
func (e *EntryPaginationBuilder) WithCategoryID(categoryID int64) {
if categoryID != 0 {
e.conditions = append(e.conditions, fmt.Sprintf("f.category_id = $%d", len(e.args)+1))
e.args = append(e.args, categoryID)
}
}
// WithStatus adds status to the condition.
func (e *EntryPaginationBuilder) WithStatus(status string) {
if status != "" {
e.conditions = append(e.conditions, fmt.Sprintf("e.status = $%d", len(e.args)+1))
e.args = append(e.args, status)
}
}
// Entries returns previous and next entries.
func (e *EntryPaginationBuilder) Entries() (*model.Entry, *model.Entry, error) {
tx, err := e.store.db.Begin()
if err != nil {
return nil, nil, fmt.Errorf("begin transaction for entry pagination: %v", err)
}
prevID, nextID, err := e.getPrevNextID(tx)
if err != nil {
tx.Rollback()
return nil, nil, err
}
prevEntry, err := e.getEntry(tx, prevID)
if err != nil {
tx.Rollback()
return nil, nil, err
}
nextEntry, err := e.getEntry(tx, nextID)
if err != nil {
tx.Rollback()
return nil, nil, err
}
tx.Commit()
if e.direction == "desc" {
return nextEntry, prevEntry, nil
}
return prevEntry, nextEntry, nil
}
func (e *EntryPaginationBuilder) getPrevNextID(tx *sql.Tx) (prevID int64, nextID int64, err error) {
defer timer.ExecutionTime(time.Now(), fmt.Sprintf("[EntryPaginationBuilder] %v, %v", e.conditions, e.args))
cte := `
WITH entry_pagination AS (
SELECT
e.id,
lag(e.id) over (order by e.published_at asc, e.id desc) as prev_id,
lead(e.id) over (order by e.published_at asc, e.id desc) as next_id
FROM entries AS e
LEFT JOIN feeds AS f ON f.id=e.feed_id
WHERE %s
ORDER BY e.published_at asc, e.id desc
)
SELECT prev_id, next_id FROM entry_pagination AS ep WHERE %s;
`
subCondition := strings.Join(e.conditions, " AND ")
finalCondition := fmt.Sprintf("ep.id = $%d", len(e.args)+1)
query := fmt.Sprintf(cte, subCondition, finalCondition)
e.args = append(e.args, e.entryID)
var pID, nID sql.NullInt64
err = tx.QueryRow(query, e.args...).Scan(&pID, &nID)
switch {
case err == sql.ErrNoRows:
return 0, 0, nil
case err != nil:
return 0, 0, fmt.Errorf("entry pagination: %v", err)
}
if pID.Valid {
prevID = pID.Int64
}
if nID.Valid {
nextID = nID.Int64
}
return prevID, nextID, nil
}
func (e *EntryPaginationBuilder) getEntry(tx *sql.Tx, entryID int64) (*model.Entry, error) {
var entry model.Entry
err := tx.QueryRow(`SELECT id, title FROM entries WHERE id = $1`, entryID).Scan(
&entry.ID,
&entry.Title,
)
switch {
case err == sql.ErrNoRows:
return nil, nil
case err != nil:
return nil, fmt.Errorf("fetching sibling entry: %v", err)
}
return &entry, nil
}
// NewEntryPaginationBuilder returns a new EntryPaginationBuilder.
func NewEntryPaginationBuilder(store *Storage, userID, entryID int64, direction string) *EntryPaginationBuilder {
return &EntryPaginationBuilder{
store: store,
args: []interface{}{userID, "removed"},
conditions: []string{"e.user_id = $1", "e.status <> $2"},
entryID: entryID,
direction: direction,
}
}