table: introduced table package

It adds support for super simple CRUD operations based on table schema model.

table/table.go

@@ -0,0 +1,108 @@
+// Copyright (C) 2017 ScyllaDB
+// Use of this source code is governed by a ALv2-style
+// license that can be found in the LICENSE file.
+
+package table
+
+import "github.com/scylladb/gocqlx/qb"
+
+// Metadata represents table schema.
+type Metadata struct {
+	Name    string
+	Columns []string
+	PartKey []string
+	SortKey []string
+}
+
+type cql struct {
+	stmt  string
+	names []string
+}
+
+// Table allows for simple CRUD operations, it's backed by query builders from
+// gocqlx/qb package.
+type Table struct {
+	metadata      Metadata
+	primaryKeyCmp []qb.Cmp
+	partKeyCmp    []qb.Cmp
+
+	get    cql
+	sel    cql
+	insert cql
+}
+
+// New creates new Table based on table schema read from Metadata.
+func New(m Metadata) *Table {
+	t := &Table{
+		metadata: m,
+	}
+
+	// prepare primary and partition key comparators
+	t.primaryKeyCmp = make([]qb.Cmp, 0, len(m.PartKey)+len(m.SortKey))
+	for _, k := range m.PartKey {
+		t.primaryKeyCmp = append(t.primaryKeyCmp, qb.Eq(k))
+	}
+	for _, k := range m.SortKey {
+		t.primaryKeyCmp = append(t.primaryKeyCmp, qb.Eq(k))
+	}
+	t.partKeyCmp = t.primaryKeyCmp[:len(t.metadata.PartKey)]
+
+	// prepare get stmt
+	t.get.stmt, t.get.names = qb.Select(m.Name).Where(t.primaryKeyCmp...).ToCql()
+	// prepare select stmt
+	t.sel.stmt, t.sel.names = qb.Select(m.Name).Where(t.partKeyCmp...).ToCql()
+	// prepare insert stmt
+	t.insert.stmt, t.insert.names = qb.Insert(m.Name).Columns(m.Columns...).ToCql()
+
+	return t
+}
+
+// Name returns table name.
+func (t *Table) Name() string {
+	return t.metadata.Name
+}
+
+// Get returns select by primary key statement.
+func (t *Table) Get(columns ...string) (stmt string, names []string) {
+	if len(columns) == 0 {
+		return t.get.stmt, t.get.names
+	}
+
+	return qb.Select(t.metadata.Name).
+		Columns(columns...).
+		Where(t.primaryKeyCmp...).
+		ToCql()
+}
+
+// Select returns select by partition key statement.
+func (t *Table) Select(columns ...string) (stmt string, names []string) {
+	if len(columns) == 0 {
+		return t.sel.stmt, t.sel.names
+	}
+
+	return qb.Select(t.metadata.Name).
+		Columns(columns...).
+		Where(t.primaryKeyCmp[0:len(t.metadata.PartKey)]...).
+		ToCql()
+}
+
+// SelectBuilder returns a builder initialised to select by partition key
+// statement.
+func (t *Table) SelectBuilder(columns ...string) *qb.SelectBuilder {
+	return qb.Select(t.metadata.Name).Columns(columns...).Where(t.partKeyCmp...)
+}
+
+// Insert returns insert all columns statement.
+func (t *Table) Insert() (stmt string, names []string) {
+	return t.insert.stmt, t.insert.names
+}
+
+// Update returns update by primary key statement.
+func (t *Table) Update(columns ...string) (stmt string, names []string) {
+	return qb.Update(t.metadata.Name).Set(columns...).Where(t.primaryKeyCmp...).ToCql()
+}
+
+// Delete returns delete by primary key statement.
+func (t *Table) Delete(columns ...string) (stmt string, names []string) {
+	return qb.Delete(t.metadata.Name).Columns(columns...).Where(t.primaryKeyCmp...).ToCql()
+}