Function Find

cmd/cql-proxy/resolver/query_builder.go:26–82

Find process find query with filter/project/order by/limits like a mongodb.

(table string, availFields FieldMap, query map[string]interface{}, projection map[string]interface{},
	orderBy map[string]interface{}, skip *int64, limit *int64)

// Find process find query with filter/project/order by/limits like a mongodb.
func Find(table string, availFields FieldMap, query map[string]interface{}, projection map[string]interface{},
	orderBy map[string]interface{}, skip *int64, limit *int64) (
	statement string, args []interface{}, fields FieldMap, err error) {
	fields = FieldMap{}
	statement = `SELECT `

	// project segment
	projectionFields, projectionStatement, err := ResolveProjection(projection, availFields)
	if err != nil {
		err = errors.Wrapf(err, "resolve query result projection failed")
		return
	}
	fields.Merge(projectionFields)
	statement += projectionStatement

	// table segment
	statement += fmt.Sprintf(` FROM "%s" `, table)

	// where segment
	filterFields, filterStatement, filterArgs, err := ResolveFilter(query, availFields)
	if err != nil {
		err = errors.Wrapf(err, "resolve query filter failed")
		return
	}
	fields.Merge(filterFields)
	args = append(args, filterArgs...)

	if filterStatement != "" {
		statement += " WHERE "
		statement += filterStatement
	}

	// order by segment
	orderByFields, orderByStatement, err := ResolveOrderBy(orderBy, availFields)
	if err != nil {
		err = errors.Wrapf(err, "resolve order by failed")
		return
	}
	fields.Merge(orderByFields)

	if orderByStatement != "" {
		statement += " ORDER BY "
		statement += orderByStatement
	}

	if skip != nil || limit != nil {
		if skip == nil {
			statement += fmt.Sprintf(" LIMIT %d", *limit)
		} else if limit == nil {
			statement += fmt.Sprintf(" LIMIT %d, -1", *skip)
		} else {
			statement += fmt.Sprintf(" LIMIT %d, %d", *skip, *limit)
		}
	}

	return
}