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rdbpagination.go
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rdbpagination.go
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package rdb
import (
"fmt"
sq "github.com/Masterminds/squirrel"
pagination_interface "github.com/crypto-com/chain-indexing/appinterface/pagination"
)
// RDbPaginationBuilder builds pagination query based on the pagination data. It supports both SQL and StmtBuilder
type RDbPaginationBuilder struct {
*pagination_interface.Pagination
customTotalQueryFn CustomTotalQueryFn
rdbHandle *Handle
}
func NewRDbPaginationBuilder(pagination *pagination_interface.Pagination, rdbHandle *Handle) *RDbPaginationBuilder {
return &RDbPaginationBuilder{
pagination,
nil,
rdbHandle,
}
}
func (pagination *RDbPaginationBuilder) WithCustomTotalQueryFn(fn CustomTotalQueryFn) *RDbPaginationBuilder {
pagination.customTotalQueryFn = fn
return pagination
}
func (pagination *RDbPaginationBuilder) BuildStmt(stmtBuilder sq.SelectBuilder) *RDbPaginationStmtBuilder {
return &RDbPaginationStmtBuilder{
Pagination: pagination.Pagination,
rdbHandle: pagination.rdbHandle,
stmtBuilder: stmtBuilder,
customTotalQueryFn: pagination.customTotalQueryFn,
}
}
func (pagination *RDbPaginationBuilder) BuildSQL(sql string, args ...interface{}) *RDbPaginationSQLBuilder {
return &RDbPaginationSQLBuilder{
Pagination: pagination.Pagination,
rdbHandle: pagination.rdbHandle,
sql: sql,
args: args,
}
}
// RDbPaginationBuilder is the concrete implementation to builds the pagination for StmtBuilder
type RDbPaginationStmtBuilder struct {
*pagination_interface.Pagination
rdbHandle *Handle
stmtBuilder sq.SelectBuilder
customTotalQueryFn CustomTotalQueryFn
}
func (pagination *RDbPaginationStmtBuilder) ToStmtBuilder() sq.SelectBuilder {
switch pagination.Type() {
case pagination_interface.PAGINATION_OFFSET:
params := pagination.OffsetParams()
return pagination.stmtBuilder.Suffix("LIMIT ? OFFSET ?", params.Limit, params.Offset())
}
return pagination.stmtBuilder
}
func (pagination *RDbPaginationStmtBuilder) Result() (*pagination_interface.PaginationResult, error) {
switch pagination.Type() {
case pagination_interface.PAGINATION_OFFSET:
return pagination.offsetResult()
}
return nil, nil
}
func (pagination *RDbPaginationStmtBuilder) offsetResult() (*pagination_interface.PaginationResult, error) {
var err error
sql, sqlArgs, err := pagination.stmtBuilder.ToSql()
if err != nil {
return nil, fmt.Errorf("error building total count select SQL: %v", err)
}
var total int64
if pagination.customTotalQueryFn != nil {
total, err = pagination.customTotalQueryFn(pagination.rdbHandle, pagination.stmtBuilder)
if err != nil {
return nil, fmt.Errorf("error executing custom total query function: %v", err)
}
} else {
// No new parameter is introduced in the prepared statement. Should not
// violate security
// nolint:gosec
sql = fmt.Sprintf("SELECT COUNT(*) FROM (%s) counting_table", sql)
if err = pagination.rdbHandle.QueryRow(sql, sqlArgs...).Scan(&total); err != nil {
return nil, fmt.Errorf("error executing total count select SQL: %v", err)
}
}
return pagination.OffsetResult(total), nil
}
// RDbPaginationBuilder is the concrete implementation to builds the pagination for SQL query
type RDbPaginationSQLBuilder struct {
*pagination_interface.Pagination
rdbHandle Runner
sql string
args []interface{}
}
func (pagination *RDbPaginationSQLBuilder) ToSQL() (string, []interface{}) {
switch pagination.Type() {
case pagination_interface.PAGINATION_OFFSET:
lastPlacerHolder := len(pagination.args)
params := pagination.OffsetParams()
args := make([]interface{}, 0, len(pagination.args))
copy(args, pagination.args)
return fmt.Sprintf("%s LIMIT $%d OFFSET $%d",
pagination.sql, lastPlacerHolder+1, lastPlacerHolder+2,
), append(pagination.args, params.Limit, params.Offset())
}
return pagination.sql, pagination.args
}
func (pagination *RDbPaginationSQLBuilder) Result() (*pagination_interface.PaginationResult, error) {
switch pagination.Type() {
case pagination_interface.PAGINATION_OFFSET:
return pagination.offsetResult()
}
return nil, nil
}
func (pagination *RDbPaginationSQLBuilder) offsetResult() (*pagination_interface.PaginationResult, error) {
var err error
// No new parameter is introduced in the prepare statement. Hence not
// violating security
// nolint:gosec
sql := fmt.Sprintf("SELECT COUNT(*) FROM (%s) counting_table", pagination.sql)
var total int64
if err = pagination.rdbHandle.QueryRow(sql, pagination.args...).Scan(&total); err != nil {
return nil, fmt.Errorf("error executing total count select SQL: %v", err)
}
return pagination.OffsetResult(total), nil
}
type CustomTotalQueryFn = func(conn *Handle, originalSelectBuilder sq.SelectBuilder) (int64, error)
//"SELECT reltuples::bigint FROM pg_class where relname='$1';