Remap

The Remap transform component uses an expr-based engine to transform incoming messages by applying custom remapping logic.

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Class Definition

class Remap extends Transform {
  fixed sourceName = "remap"
  code: String
}

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Attributes

Attribute	Type	Description	Default Value
code	String	The remapping rule written in the expr engine syntax.	Required

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I/O Types

• Input Type: map[string]any, map[string][]any,string, []byte(value), []byte
• Output Type: map[string]any

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Pkl Configuration Example

Basic Remap Transform

new Transforms.Remap {
  name = "example-remap"
  code = "{ "value_name": Data.name, "value_price": Data.price }"
}

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Description

The Remap transform component allows you to transform or modify incoming messages based on custom rules defined in the expr language. This is particularly useful for altering the structure or content of messages before they are passed downstream.

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Unit Test Example in Go

The following test demonstrates remapping a message by extracting specific fields and creating a new structure:

{
	name: "test expr maps return nil",
	args: args{
		val: map[string]any{
			"id":       1,
			"name":     "iPhone 12",
			"price":    999,
			"quantity": 1,
		},
		code: "{ "value_name": Data.name, "value_price": Data.price }",
	},
	want: map[string]any{
		"value_name":  "iPhone 12",
		"value_price": 999,
	},
},

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Pkl Configuration Matching Unit Test

The equivalent Pkl configuration for the test case above:

new Transforms.Remap {
  name = "remap-extract-fields"
  code = "{ "value_name": Data.name, "value_price": Data.price }"
}

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Use Cases

1. Data Transformation
   • Modify fields in incoming messages, such as scaling values or changing formats.
2. Data Enrichment
   • Add new fields or compute derived values based on existing fields.

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Notes

• The code attribute must be a valid expr rule.
• Ensure the rule logic aligns with the structure of incoming messages for accurate transformations.

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