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Transform Functions
Transform functions are used to extract and/or reformat data returned by a hydrate function into the desired type/format for a column. You can call your own transform function with From, but you probably don't need to write one -- The SDK provides many that cover the most common cases. You can chain transforms together, but the transform chain must be started with a From function:
| Name | Description |
|---|---|
| FromConstant | Return a constant value (specified by 'param'). |
| FromField | Generate a value by retrieving a field from the source item. |
| FromValue | Generate a value by returning the raw hydrate item. |
| FromCamel | Generate a value by converting the given field name to camel case and retrieving from the source item. |
| FromGo | Generate a value by converting the given field name to camel case and retrieving from the source item. |
| From | Generate a value by calling a 'transformFunc'. |
| FromJSONTag | Generate a value by finding a struct property with the json tag matching the column name. |
| FromTag | Generate a value by finding a struct property with the tag 'tagName' matching the column name. |
| FromP | Generate a value by calling 'transformFunc' passing param. |
Additional functions can be chained after a From function to transform the data:
| Name | Description |
|---|---|
| Transform | Apply an arbitrary transform to the data (specified by 'transformFunc'). |
| TransformP | Apply an arbitrary transform to the data, passing a parameter. |
| NullIfEqual | If the input value equals the transform param, return nil. |
| NullIfZero | If the input value equals the zero value of its type, return nil. |