Parameter Types 

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When writing expressions, it is important to consider the type of the result. For example, if you have written a Stream Attribute you can write an expression to return the integer 3 but have defined the type of the Stream Attribute stream attribute to be a String then PhixFlow will stop and report the error a string. If there is a mis-match between data types, when the expression is evaluated, PhixFlow stops evaluating the expression and reports an error.

The full list of types handled by PhixFlow is shown below. It's not necessary to understand the meaning of the individual types at this stage, however just be aware that the different types exist.in the following table. 

Using $-variables in Calculations

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In stream attribute expressions that have complex calculations, you may need a variable to hold the result of a calculation. You can then reference the variable later in the expression, or in other attribute expressions for the same stream. In PhixFlow you can use a $-variable for this, by prefixing the variable name with the $ symbol.

do(
   $A = 5,
   $B = 2,

   $A*$B
)

do(
   $c = 10,


   $A*$B*$C
)

$-variables are not really needed in simple calculations. They are useful:

• in forEach loops
• when using look-up pipesCalculating attibute names from pipes; see Assigning Values From a Pipe, below.
• to store a value from a look-up pipe, when you need the value in multiple attributes.
  1. In the first attribute, look-up the value.
  2. Use a $-variable to store the value that is returned by the look-up.
  3. When you need the value in another attribute, reference the $-variable instead of repeating the look-up.
• in complex expressions, to break up multiple consecutive functions into separate lines. In this case, use a $-variable to store the intermediate values; see Multiline Statements and $-variables, below.

Assigning Values From a

Pipe 

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Stream attribute expressions are commonly used to fetch the value returned by a Pipe. This is simply done by suffixing the Pipe pipe name with the name of the attribute to be returned. For example: 

  in.accountRef

This expression causes PhixFlow to look at the pipe named "in" and return the value in the field called "accountRef".

Calculating an Attribute Name

If the name of the attribute whose value you want has to be calculated based on other factors

, you can assign the attribute name

to a

$-variable. You then use the variable instead of the attribute name itself

.

For example:

  in.$attrName

Handling Invalid Characters

There are two options for handling an attribute name that contains invalid characters.

• Either assign that name to a variable

• and use the variable instead of the actual attribute

• .
• Or enclose the name in quotes

• , for example:  in.'account-ref'.

Mathematical Operators (+, -, *, /)

Several values can be combined using the usual basic mathematical operators. For example when in.numProducts has the value 9:

The usual calculation precedences apply i.e. , so * and / operations are carried out before + and -. When the mathematical statements involve multiple calculations, use brackets ( ) can be used to force the correct processing order:.

String Concatenation (+)

The + operator also serves as the string concatenation operator i.e. joins . This means you can use + to  join strings together. For example if in.customerName returns "Smith" and in.title returns "Mr":

Multiline Statements and $-variables

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Often there is a need to work out the result of a When you are working with more complex expression which , you may require have several different statements to be evaluated evaluate first. To group several statements together in this way, you should make use of the do() function. In nearly all multiline statements, it is also very convenient

In multi-line statements, you usually need to assign the value of an expression to a $-variable which may then be used , to use later in the expression. For example:

The value of an expression , that is the value that will be assigned into the stream attributeused, is the value of the last statement to be evaluated. In simple expressions, such as the example above example, the last statement to be evaluated is the last line. However, in Conditional Statements, the last statement evaluated is not always the last statement in the expression. For example:

Adding Comments

It is always a good idea to add comments to your scripts to explain its steps. These Comments help anyone who needs to modify the script in future.

There are two ways to tell PhixFlow that a line is a comment, and can be ignored.

For example:

/* Get the discount rate that should apply to 
the calls that match the filter conditions */
$discountRate = discount.rate,

// Now apply the discount
$value = $value * ( 1 - $discountRate)

See Also

•  Expressions and Scripts topic page for links to more information.