I am developing an angular app using the 8th version. Inside the `ngIf` expression, I want to check something existanse inside array. So I have written the expression below:

```
*ngIf="questionniare.factors.some(item => item.intensities.length > 0)"

```

But now I get this error inside the console window:

> 
> Parser Error: Bindings cannot contain assignments at column 34 in
>  [questionniare.factors.some(item => item.intensities.length > 0)]
> 
> 
> 

But as see, I don't have any assignment in my condition. So what's the problem and how can I fix it?

(I know that I can define a method and do this job inside that method, but I want to know if this is a limitation on ngIf that I should consider next times?)