142 lines
3.5 KiB
Go
142 lines
3.5 KiB
Go
package categories
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import (
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"database/sql"
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"errors"
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"fmt"
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_ "github.com/lib/pq"
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"strings"
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)
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type Category struct {
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Id int
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Name string
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Parent sql.NullInt64
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Children []*Category
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}
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var CategoriesTree []*Category = nil
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var CategoriesFlat map[int]*Category = nil
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// Cavet: slight cheat. All parents must have Category_id < their children.
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func LoadCategories(db *sql.DB) {
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if CategoriesFlat != nil {
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return //already loaded
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}
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CategoriesTree = []*Category{}
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CategoriesFlat = make(map[int]*Category)
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rows, err := db.Query("select categories.id, categories.name, categories.parent_id from categories order by coalesce(parent_id, id), parent_id is not null")
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if err != nil {
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fmt.Println("DB Error loading Categories:", err)
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return
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}
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defer rows.Close()
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for rows.Next() {
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category := &Category{Children: []*Category{}}
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err = rows.Scan(&category.Id, &category.Name, &category.Parent)
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if err != nil {
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fmt.Println("Categories DB Error: ", err)
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}
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CategoriesFlat[category.Id] = category
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if category.Parent.Valid {
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pid := int(category.Parent.Int64)
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CategoriesFlat[pid].Children = append(CategoriesFlat[pid].Children, category)
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} else {
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CategoriesTree = append(CategoriesTree, category)
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}
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}
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}
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func Add(db *sql.DB, name string, parent int) error {
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var err error
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if parent < 0 {
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_, err = db.Exec("INSERT INTO categories (name) VALUES ($1)", name)
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} else {
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_, err = db.Exec("INSERT INTO categories (name, parent_id) VALUES ($1, $2)", name, parent)
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}
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if err != nil {
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fmt.Println("Categories DB Error Add(): ", err)
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}
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return err
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}
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// Get parent id
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// Set parent of children to parent
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// set category of news to parent
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// finallly delete
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func Delete(db *sql.DB, id int) error {
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rows, err := db.Query("SELECT parent_id FROM categories WHERE id=$1", id)
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if err != nil {
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fmt.Println("Categories DB Error loading category parent id: ", err)
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return err
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}
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if !rows.Next() {
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fmt.Println("Categories DB Error loading category parent id: no category")
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return errors.New("No category")
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}
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var parent_id sql.NullInt64
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err = rows.Scan(&parent_id)
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_, err = db.Exec("UPDATE categories SET parent_id =$2 WHERE parent_id=$1", id, parent_id)
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if err != nil {
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fmt.Println("Categories DB error changing child parent: ", err)
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return err
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}
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_, err = db.Exec("UPDATE news SET category_id =$2 WHERE category_id=$1", id, parent_id)
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if err != nil {
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fmt.Println("Categories DB error changing category of news: ", err)
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return err
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}
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_, err = db.Exec("DELETE FROM categories WHERE id=$1", id)
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if err != nil {
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fmt.Println("Categories DB Error Delete(): ", err)
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}
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return err
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}
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func GetListOfChildrenIds(id int) []int {
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list := []int{id}
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for _,category := range CategoriesFlat[id].Children {
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list = append(list, GetListOfChildrenIds(category.Id)...)
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}
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return list
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}
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func (category *Category) ChangeParent(db *sql.DB, parent *Category) error {
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var err error
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if parent == nil {
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_, err = db.Exec("UPDATE categories SET parent_id = NULL WHERE id = $1", category.Id)
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} else {
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_, err = db.Exec("UPDATE categories SET parent_id = $2 WHERE id = $1", category.Id, parent.Id)
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}
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if err != nil {
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fmt.Println("Categories DB Error: ", err)
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}
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return err
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}
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// get the number of parents a category has
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func (category *Category) Depth() int {
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depth := 0
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current := category
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for current.Parent.Valid {
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current = CategoriesFlat[int(current.Parent.Int64)]
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depth++
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}
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return depth
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}
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// Helper function for templates (add form select list)
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func (category *Category) ToString() string {
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return strings.Repeat("- ", category.Depth()) + category.Name
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}
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