Versions Compared

Key

  • This line was added.
  • This line was removed.
  • Formatting was changed.

Arrays

...

Arrays

An Array is an object that contains an ordered list of other objects. For example the following creates an Array of 7 items and assigns it into the $-Variable $weekDays:

...

  • The simplest case is shown above i.e. the Array is created explicitly using the [value1, value2,..] syntax.
  • An Array of Integers between the values n and m can be created using the expression [n..m] e.g. [51..100] creates an Array of 50 elements [51, 52, ... 100].
  • Arrays can also be created by Array Handling Functions functions e.g. split() which turns a String into an Array.
  • Finally an Array can be generated by referring to an Attribute on a Pipe when that Pipe contains several rows. In this case the Array has an entry for each row in the Pipe and the value of each entry is value of the specified Attribute. For example:

...

Note that $oddArray[5] is itself an Array! This can be useful in some very complex processing logic.

Getting / Setting the value of an Array Element

To use the nth item in the Array, use either the syntax array[n] or getElement(array,n) or array.n :

ExpressionResult
$day = $weekDays[3]Sets $day to "Wednesday"
$i = 3, $day = $weekDays[$i+2]Sets $day to "Friday"
$day = getElement($weekDays,4)Sets $day to "Thursday"
$day = $weekDays.3Sets $day to "Wednesday"
$day = $weekDays[9]Sets $day to _NULL since there is no element at position 9
$weekDays = _NULL, $day = $weekDays.3Sets $day to _NULL since there is no element at position 3 (in fact there are no elements at all)
$weekDays = [], $day = getElement($weekDays,3)Sets $day to _NULL since there is no element at position 3 (in fact there are no elements at all)

 

Similarly, to set the value of the nth item in an Array, use setElement(array,n,value):

...

However setElement($months,13,"Lunar") would cause PhixFlow to generate an error and stop processing as the expression is trying to update an item that do not exist.

Array Operations

See Array Handling Functions for a full list functions that can be used with Arrays. However the most frequently used functions are:

FunctionDescription
getElement()Get the value of a specific element within an Array
addElement()Add a new element to the end of an Array
countElements()Get the number of elements within an Array
listContains()Provides the position of a value within an Array
split()Turn a String of delimited values (e.g. a comma-separated list) into an Array

Records Sets

A Record Set is an object containing one or more rows of data (usually returned from a Pipe). Entries within Record Sets can be referred to using the name of the Attribute value. In the examples below:

  • account is a Pipe which contain a single record of account details.
  • invoices is a Pipe which contains several invoice records for that account.
ExpressionResult
$accountNum = account.accountNumaccount.accountNum returns the value of the Attribute accountNum within the Record Set account. Because the Pipe just returns a single value, $accountNum is a single value (not an Array).
$invoiceNumbers = invoices.numberinvoices.number returns an Array of the Attribute number within the Record Set invoices.
$firstInvoiceNumber = invoices.number[1]This gets the first invoice number.
$firstInvoice = invoices[1], $firstInvoiceNumber = $firstInvoice.numberThis also gets the first invoice number. Note that the Record Set invoices[1] has been assigned into a $-Variable.
$attr = "number", $invoiceNumbers = invoices.$attrThis also creates an Array of the invoice numbers. Note that the $-Variable $attr has been set to the name of the Attribute which is then used to decide which Attribute to read from invoices.

Syntax pipe.attribute1:attribute2

Sometimes it is useful to construct a new Record Set containing a subset of the Attributes on the original Pipe. This can be done using the syntax:

...

This form is useful when comparing selected Attributes on one Pipe with selected Attributes on another Pipe. For example:

ExpressionResult
eq(newAccount.accountNum:customerId:custName, oldAccount.accNumber:custId:customerName)This returns true if the Pipes newAccount and oldAccount contain matching details for the referenced Attributes.