default.go

package pipeline

import "fmt"

// Defaults fields and tags on data points.
//
// Example:
//    stream
//        |default()
//            .field('value', 0.0)
//            .tag('host', '')
//
// The above example will set the field `value` to float64(0) if it does not already exist
// It will also set the tag `host` to string("") if it does not already exist.
//
// Available Statistics:
//
//    * fields_defaulted -- number of fields that were missing
//    * tags_defaulted -- number of tags that were missing
//
type DefaultNode struct {
	chainnode

	// Set of fields to default
	// tick:ignore
	Fields map[string]interface{} `tick:"Field"`

	// Set of tags to default
	Tags map[string]string `tick:"Tag"`
}

func newDefaultNode(e EdgeType) *DefaultNode {
	n := &DefaultNode{
		chainnode: newBasicChainNode("default", e, e),
		Fields:    make(map[string]interface{}),
		Tags:      make(map[string]string),
	}
	return n
}

// Define a field default.
// tick:property
func (n *DefaultNode) Field(name string, value interface{}) *DefaultNode {
	n.Fields[name] = value
	return n
}

// Define a tag default.
// tick:property
func (n *DefaultNode) Tag(name string, value string) *DefaultNode {
	n.Tags[name] = value
	return n
}

func (n *DefaultNode) validate() error {
	for field, value := range n.Fields {
		switch value.(type) {
		case float64:
		case int64:
		case bool:
		case string:
		default:
			return fmt.Errorf("unsupported type %T for field %q, field default values must be float,int,string or bool", value, field)
		}
	}
	return nil
}