Question: Suppose I have a `foreach` inside of a pipe:

[![enter image description here](https://i.stack.imgur.com/RSwqi.png)](https://i.stack.imgur.com/RSwqi.png)

I'd like to iterate through the following:

`@split(split(item().name,'_')[4],'-')[1]`

However, I'd like to pass this formula in through a parameter.

I've defined a parameter `myExpression` with the desired value in the pipeline, and attempting to reference it like so:

[![enter image description here](https://i.stack.imgur.com/BJvMh.png)](https://i.stack.imgur.com/BJvMh.png)

Note that the full expression would be: `{@pipeline().parameters.myExpression}`

However, data factory does not execute that expression, rather it just accepts it as a verbatim string: 

> 
> {@pipeline().parameters.myExpression}
> 
> 
> 

**How do we pass in an expression from parameters from within the pipeline?**

Answer: 
When you define a parameter like this and pass the value, what you are doing is is send a string input, as the textbox doesn't accept expression. The only way to pass expression to a parameter is to pass it from another pipeline. Another issue we have is one ADF limitation - there can not be nested iterations. Calling a second pipeline solves both the issues.

Split your flow in two pipelines. 

First (parent) pipeline - Keep all steps up until generating the array over which iteration has to happen. 

```
@split(split(item().name,'_')[4],'-')[1]

```

Then, inside a for each loop, invoke an "Execute pipeline" activity. In there, pass the expression that you desire in a similar fashion- 

[![enter image description here](https://i.stack.imgur.com/z5XeK.png)](https://i.stack.imgur.com/z5XeK.png)

In the child pipeline, define a string parameter to absorb the passed value. Then, use **@pipeline().parameters.ParamName** to use it in there.

HTH
your description lacks a lot of context of what are you trying to do. I can only presume that you generate array in one pipeline and you want to iterate it in another. Looking at your print screen it looks like you typed in your value, therefore output is a plain text. you should hit dynamic context
[![enter image description here](https://i.stack.imgur.com/LPk5y.png)](https://i.stack.imgur.com/LPk5y.png)

so it would look like this:

[![enter image description here](https://i.stack.imgur.com/e3xx6.png)](https://i.stack.imgur.com/e3xx6.png)