eb033c4922
Builder is not in a position to validate the statement and the effort is duplicated when the query is build. The checked errors are simple and do not occur most of the time.
144 lines
2.9 KiB
Go
144 lines
2.9 KiB
Go
package qb
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// SELECT reference:
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// http://docs.datastax.com/en/dse/5.1/cql/cql/cql_reference/cql_commands/cqlSelect.html
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import (
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"bytes"
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"fmt"
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)
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type Order bool
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const (
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ASC Order = true
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DESC = false
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)
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type SelectBuilder struct {
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table string
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columns columns
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distinct columns
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where where
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groupBy columns
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orderBy string
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order Order
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limit uint
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limitPerPartition uint
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allowFiltering bool
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}
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// Select returns a new SelectBuilder with the given table name.
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func Select(table string) *SelectBuilder {
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return &SelectBuilder{
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table: table,
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}
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}
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func (b *SelectBuilder) ToCql() (stmt string, names []string) {
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cql := bytes.Buffer{}
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cql.WriteString("SELECT ")
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switch {
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case len(b.distinct) > 0:
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cql.WriteString("DISTINCT ")
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b.distinct.writeCql(&cql)
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case len(b.groupBy) > 0:
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b.groupBy.writeCql(&cql)
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cql.WriteByte(',')
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b.columns.writeCql(&cql)
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case len(b.columns) == 0:
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cql.WriteByte('*')
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default:
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b.columns.writeCql(&cql)
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}
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cql.WriteString(" FROM ")
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cql.WriteString(b.table)
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cql.WriteByte(' ')
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names = b.where.writeCql(&cql)
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if len(b.groupBy) > 0 {
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cql.WriteString("GROUP BY ")
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b.groupBy.writeCql(&cql)
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cql.WriteByte(' ')
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}
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if b.orderBy != "" {
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cql.WriteString("ORDER BY ")
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cql.WriteString(b.orderBy)
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if b.order {
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cql.WriteString(" ASC ")
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} else {
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cql.WriteString(" DESC ")
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}
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}
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if b.limit != 0 {
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cql.WriteString("LIMIT ")
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cql.WriteString(fmt.Sprint(b.limit))
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cql.WriteByte(' ')
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}
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if b.limitPerPartition != 0 {
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cql.WriteString("PER PARTITION LIMIT ")
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cql.WriteString(fmt.Sprint(b.limitPerPartition))
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cql.WriteByte(' ')
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}
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if b.allowFiltering {
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cql.WriteString("ALLOW FILTERING ")
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}
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stmt = cql.String()
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return
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}
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// From sets the table to be selected from.
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func (b *SelectBuilder) From(table string) *SelectBuilder {
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b.table = table
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return b
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}
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func (b *SelectBuilder) Columns(columns ...string) *SelectBuilder {
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b.columns = append(b.columns, columns...)
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return b
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}
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func (b *SelectBuilder) Distinct(columns... string) *SelectBuilder {
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b.distinct = append(b.distinct, columns...)
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return b
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}
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func (b *SelectBuilder) Where(w ...Cmp) *SelectBuilder {
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b.where = append(b.where, w...)
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return b
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}
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// GroupBy sets GROUP BY clause on the query. Columns must be a primary key,
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// this will automatically add the the columns as first selectors.
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func (b *SelectBuilder) GroupBy(columns... string) *SelectBuilder {
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b.groupBy = append(b.groupBy, columns...)
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return b
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}
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func (b *SelectBuilder) OrderBy(column string, o Order) *SelectBuilder {
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b.orderBy, b.order = column, o
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return b
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}
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func (b *SelectBuilder) Limit(limit uint) *SelectBuilder {
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b.limit = limit
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return b
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}
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func (b *SelectBuilder) LimitPerPartition(limit uint) *SelectBuilder {
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b.limitPerPartition = limit
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return b
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}
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func (b *SelectBuilder) AllowFiltering() *SelectBuilder {
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b.allowFiltering = true
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return b
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}
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