{"id":9462,"date":"2016-02-18T09:24:19","date_gmt":"2016-02-18T01:24:19","guid":{"rendered":"http:\/\/localhost\/help\/?page_id=9462"},"modified":"2024-07-04T16:09:42","modified_gmt":"2024-07-04T08:09:42","slug":"eval","status":"publish","type":"page","link":"https:\/\/oihelp.corporate.ifs.com\/help\/p2-server\/calculations\/eval\/","title":{"rendered":"Eval()"},"content":{"rendered":"\n

Format<\/h2>\n

Eval(String[, ParamsArray])<\/strong><\/p>\n

Returns<\/h2>\n

Evaluates the specified expression.\u00a0Optionally it can also override the value of context parameters<\/a> for the duration of the evaluation.<\/p>\n

Behaves in exactly the same way as the EvalExp() function, except that the first parameter\u2019s type is a single value string\u00a0<\/i>and not an expression.\u00a0<\/p>\n

Use caution when nesting the Eval() functions, as they can quickly become complicated and difficult to troubleshoot.<\/strong><\/p>\n

Inputs<\/h2>\n

String<\/strong>: The string to be evaluated.
\nBehaviour: Required
\nDimension: SingleValue
\nNote: Also supports a single string that contains an expression which returns a multi-collection variable, but a multi-collection of string is not supported.<\/em>
\nValid\u00a0data types: String<\/p>\n

Note: This string will be treated as an expression and sent to IFS OI Server to be resolved. The function will return the result of the expression.<\/p>\n

ParamsArray<\/strong>:\u00a0The context parameters to be used to override the default context parameters of the expression.
\nBehaviour: Optional [0..n]
\nDimension: Collection, SingleValue, Matrix
\nValid data types: Null, Boolean, DateTime, Decimal, Integer, String, Duration, Error<\/p>\n

Note:\u00a0These parameters must be specified in pairs. The first parameter must be the name of a single value context parameter and the second parameter must be the value of it.
\nE.g. Eval(\"{myTag}\", \"sampleMethod\", \"Raw\")<\/span>. This will evaluate the \"{myTag}\" string\u00a0with the sample method set to \"Raw\" in the string\u00a0context. Note the use of {} around the tag name.<\/p>\n

How to format data types<\/a><\/p>\n

When to use<\/h2>\n

Both Eval() and EvalExp() can be used for evaluating expressions with overridden context parameters.\u00a0The difference is that the first parameter of Eval() is a string while the first parameter of EvalExp() is an expression.<\/p>\n

Here is an example showing the difference (without using context parameters, for simplicity):<\/p>\n

Eval(\"1 + 2\")<\/span> -> returns 3
\nEvalExp(1 + 2)<\/span> -> returns 3<\/p>\n

The most obvious difference is that Eval() expects a string and therefore the first parameter must be wrapped in quotation marks.\u00a0As EvalExp() expects an expression parameter, it doesn\u2019t require quotes.<\/p>\n

This means that you can use Eval() to evaluate a string which is generated and not hard-coded (as if it was an expression).<\/p>\n

You should use Eval() if you have a string (which is often generated as the result of a sub-expression) and you want to treat that as an expression and evaluate it with or without overridden context parameters. Otherwise, use EvalExp().<\/p>\n

Examples<\/h2>\n

Expression:\u00a0Eval(\"1+2\")<\/span>
\nExpected result:\u00a03<\/p>\n

Expression: Eval(\"{\" + entity + \":attribute}\")<\/span>
\nExpected result: Fetches the entity:attribute<\/em> attribute value and return its value as a collection variable<\/p>\n

Release History<\/span><\/h2>\n