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1. Open the flow where you wish to apply the flow parameter. 
2. From the Flow View context menu, select Parameters.
3. In the Manage Parameters dialog, click the Parameters tab. 
4. Click Add parameter.

5. Enter a Name for your parameter.
   
   

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   NOTE: Name values are case-sensitive. After saving a flow parameter, its name cannot be changed.

6. (optional) Specify a user-friendly Description value.
7. For Type, select the type of parameter. See below.

Variable type parameter

Variable type parameters are single values that can be one of the following formats:

Here is my String value.

`{letter}+`

/[a-zA-z]+/

Additional steps:

1. Enter a default value for this parameter.

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   NOTE: Input Values are evaluated as String type.

2. Click Save.

The parameter is available for use in any recipe in your flow. See "Use Parameter."

Selector type parameter

Selector type parameters are lists of one or more permitted values.

Additional steps:

1. Under Choices, enter a value.

   Tip
   Tip: The first value that you add is the default value.

2. Click Add.
3. Repeat the above steps until all permitted values have been added.
4. Click Save.

The parameter is available for use in any recipe in your flow. See "Use Parameter."

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• Upstream parameter values: Parameter values can be inherited from upstream recipes and datasets. 
  
  

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  NOTE: Override values applied in a downstream flow are applied to the upstream flow when its objects are invoked for purposes of generating data for use in the downstream flow.

•  Downstream parameter values: Downstream flows receive parameter values, default or overridden, from upstream flows. These values can be overridden at the flow level.

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This override value is applied to all references to the parameter in the flow. 

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Override Evaluation

Override values can be applied in multiple locations. Parameter values are evaluated in the following order of precedence (highest to lowest):

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Example - String parameter

In this example, data is segmented by time zone. You must create a parameter to capture the following U.S. time zones, which must be specified explicitly:

'Hawaii'
'Alaska'
'Pacific'
'Mountain'
'Central'
'Eastern'

In your flow, you create the following flow parameter:

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In the following transformation, the parameter value is inserted into a new column, paramTZ in your dataset:

You can also use the parameter as an input to a function. In the following example, the paramTimeZone parameter is merged with the values in the Store_Nbr to compute primary key storeId field:

Example - parameter with multiple values

Suppose you wish to create a flow parameter that contains multiple values. Typically, you must track these values through an array, such as the following containing a set of colors:

["red","white","blue","black"]

Flow parameters that are literals are String values only. As a workaround, you can define the above as a 

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`red|white|blue|black`

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Within your recipe, you can test for the presence of a parameter value. In the following transformation, a value of true is set in the new column isBlue if the value of $myColors is blue:

Example Variable type example - Integer parameter

Instead of segmenting the data by named time zone values, suppose your data is segmented by regions, which are numeric in number. Your flow parameter definition could look like the following:

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In the column histogram for the paramRegionId column, you can verify that the value 0 is present. Set an override outside at the flow level to insert a different value in the column. 

For more information, see PARSEINT Function.

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Variable type example - Date parameter

Suppose you need to be able to pass a date into the execution of a recipe. If no date is passed in, then the current time is used. The variable is declared as follows:

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If the inserted value is empty or null, you can insert the current timestamp:

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If there is a valid value, then it is written back to the column.See NOW Function.

You can use the following to extract the time value from the parsed date param:

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Since this value is not the parameter value specifically, the column name was listed simply as Time.

Variable type example - parameter with range of values

Suppose you need to create a parameter that can contain any two-digit value from 0 to 99. To do so, you create a flow parameter of variable type, using a 

`{digit}{digit}`

The above matches two-digit values only. It does not match single-digit values. To expand the pattern to also match single digit values, you can use this one:

`({digit}|{digit}{digit})`

• Note how the value is specified using backticks (`), which are used to indicate a

  D s lang
  item pattern

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• The vertical bars are delimiters to separate the values, when they are processed within the application.

This parameter now accepts the following values:

0-9
00-99

Selector type example - parameter with multiple values

Suppose you wish to create a flow parameter that can contain one of multiple values for color. Typically, you must track these values through an array, such as the following containing a set of colors:

["red","white","blue","black"]

Using a selector type of flow parameter, you can specify these values as choices in your permitted values list for the $myColors  flow parameter:

red
white
blue
black

In this scenario, red  is the default value.

Within your recipe, you can test for the presence of a parameter value. In the following transformation, a value of true is set in the new column isBlue if the value of $myColors is blue:

Apply Parameter Override via API

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For more information, see API Workflow Task - Run Job.