Introduce Exec interface and implementers (#1)

Reviewed-on: #1

schema/table.go

@@ -0,0 +1,176 @@
+package schema
+
+import (
+	"reflect"
+	"strings"
+
+	"git.gdulai.com/gdulai/simpleorm/util"
+)
+
+type Table struct {
+	Name        string
+	Type        reflect.Type
+	Columns     []Column
+	Constraints []Constraint
+}
+
+func (t Table) GetDDL() (string, error) {
+	var ddl strings.Builder
+	ddl.WriteString("CREATE TABLE IF NOT EXISTS " + t.Name + " (")
+	for i, col := range t.Columns {
+		if i != 0 {
+			ddl.WriteString(", ")
+		}
+		colDdl, err := col.GetDDL()
+		if err != nil {
+			return "", err
+		}
+		ddl.WriteString(colDdl)
+	}
+	for _, constr := range t.Constraints {
+		constrDdl, err := constr.GetDDL()
+		if err != nil {
+			return "", err
+		}
+		ddl.WriteString(", " + constrDdl)
+	}
+
+	ddl.WriteString(");")
+	return ddl.String(), nil
+}
+
+func (t Table) GetSelectDML() (string, error) {
+	var dml strings.Builder
+	dml.WriteString("SELECT ")
+
+	for i, col := range t.Columns {
+		if i != 0 {
+			dml.WriteString(", ")
+		}
+		colDml, err := col.GetSelectDML()
+		if err != nil {
+			return "", err
+		}
+		dml.WriteString(colDml)
+	}
+
+	dml.WriteString(" FROM " + t.Name)
+	return dml.String(), nil
+}
+
+func (t Table) GetInsertDML(count int) (string, error) {
+	var dml strings.Builder
+	dml.WriteString("INSERT INTO " + util.CamelToSnake(t.Type.Name()) + " (")
+
+	columnsLen := len(t.Columns)
+	effectiveColumnsLen := 0
+	for i, col := range t.Columns {
+		_, ok := col.Modifiers["pk"]
+		if ok {
+			continue
+		}
+
+		colDml, err := col.GetInsertDML()
+		if err != nil {
+			return "", err
+		}
+
+		dml.WriteString(colDml)
+		if i != columnsLen-1 {
+			dml.WriteString(", ")
+		}
+		effectiveColumnsLen++
+	}
+
+	dml.WriteString(") VALUES")
+
+	for i := range count {
+		if i != 0 {
+			dml.WriteString(", ")
+		}
+		for j := range effectiveColumnsLen {
+			if j == 0 {
+				dml.WriteString("(")
+			}
+			if j != effectiveColumnsLen-1 {
+				dml.WriteString("?, ")
+			} else {
+				dml.WriteString("?)")
+			}
+		}
+	}
+
+	return dml.String(), nil
+}
+
+func (t Table) GetUpdateDML() (string, error) {
+	var dml strings.Builder
+	dml.WriteString("UPDATE  " + util.CamelToSnake(t.Type.Name()) + " SET ")
+
+	colLen := len(t.Columns)
+	var pkColumns []string
+	// Colum names
+	for i, col := range t.Columns {
+		modifiers := col.Modifiers
+
+		_, ok := modifiers["pk"]
+		if ok {
+			pkColumns = append(pkColumns, col.Name)
+			continue
+		}
+
+		colDml, err := col.GetUpdateDML()
+		if err != nil {
+			return "", err
+		}
+
+		if i != colLen-1 {
+			dml.WriteString(colDml + ", ")
+		} else {
+			dml.WriteString(colDml + " ")
+		}
+
+	}
+
+	dml.WriteString("WHERE ")
+
+	for i, pkCol := range pkColumns {
+		if i != 0 {
+			dml.WriteString(" AND ")
+		}
+		dml.WriteString(pkCol + " = ?")
+	}
+
+	return dml.String(), nil
+}
+
+func (t Table) GetDeleteDML(count int) (string, error) {
+	var dml strings.Builder
+	dml.WriteString("DELETE FROM " + t.Name + " WHERE ")
+
+	for _, col := range t.Columns {
+		modifiers := col.Modifiers
+
+		_, ok := modifiers["pk"]
+		if ok {
+			if count > 1 {
+				dml.WriteString(col.Name + " IN (")
+			} else {
+				dml.WriteString(col.Name + " = ")
+			}
+		}
+	}
+
+	for i := range count {
+		if i != 0 {
+			dml.WriteString(", ")
+		}
+		dml.WriteString("?")
+	}
+
+	if count > 1 {
+		dml.WriteString(")")
+	}
+
+	return dml.String(), nil
+}