Merge pull request #204684 from kromerm/cast

Cast

Author: v-ccolin

articles/data-factory/TOC.yml

@@ -733,6 +733,8 @@ items:
       href: data-flow-assert.md   
     - name: Conditional split
       href: data-flow-conditional-split.md
+    - name: Cast
+      href: data-flow-cast.md
       displayName: split
     - name: Derived column
       href: data-flow-derived-column.md

articles/data-factory/data-flow-cast.md

@@ -0,0 +1,53 @@
+---
+title: Cast transformation in mapping data flow 
+description: Learn how to use a mapping data flow cast transformation to easily change column data types in Azure Data Factory or Synapse Analytics pipelines.
+titleSuffix: Azure Data Factory & Azure Synapse
+author: kromerm
+ms.author: makromer
+ms.reviewer: makromer
+ms.service: data-factory
+ms.subservice: data-flows
+ms.topic: conceptual
+ms.custom: synapse
+ms.date: 07/13/2022
+---
+
+# Cast transformation in mapping data flow 
+
+[!INCLUDE[appliesto-adf-asa-md](includes/appliesto-adf-asa-md.md)]
+
+[!INCLUDE[data-flow-preamble](includes/data-flow-preamble.md)]
+
+Use the cast transformation to easily modify the data types of individual columns in a data flow. The cast transformation also enables an easy way to check for casting errors.
+
+## Configuration
+
+:::image type="content" source="media/data-flow/cast-transformation-001.png" alt-text="Cast settings":::
+
+To modify the data type for columns in your data flow, add columns to "Cast settings" using the plus (+) sign.
+
+**Column name:** Pick the column you wish to cast from your list of metadata columns.
+
+**Type:** Choose the data type to cast your column to. If you pick "complex", you can then select "Define complex type" and define structures, arrays, and maps inside the expression builder.
+
+**Format:** Some data types, like decimal and dates, will allow for additional formatting options.
+
+**Assert type check:** The cast transformation allows for type checking. If the casting fails, the row will be marked as an assertion error that you can trap later in the stream.
+
+## Data flow script
+
+### Syntax
+
+```
+<incomingStream>
+    cast(output(
+		AddressID as integer,
+		AddressLine1 as string,
+		AddressLine2 as string,
+		City as string
+	),
+	errors: true) ~> <castTransformationName<>
+```
+## Next steps
+
+Modify existing columns and new columns using the [derived column transformation](data-flow-derived-column.md).