We could help better if you showed the PHP code in question.
I assume you want to do a Boolean OR search.
One way is to split the value in the textarea to individual cities, use the newCompoundFindCommand and for each city add a newFindRequestCommand and an addFindCriterion.
It's not really the PHP code that's the question.
I have an HTML textarea with postal codes. The user enters the postal codes, but for illustration, let's say it's equivalent to this static HTML:
When I get this code the lines are separated by ASCII character 10. I believe that FileMaker uses ASCII 13 as a line separator. But even substituting 13 for 10 doesn't result in any records being retrieved (even though I'm using values that work individually, if only a single line is specified).
The first question is whether the FileMaker PHP API supports multi-key searches (as it does via a FileMaker client). And, if so, what character it expects to delimit the individual keys on separate lines.
The reason to NOT use compound finds (I am already using them for different purposes) is that if I end up with multiple fields like this the size and complexity of the find command will explode. I'd rather do it like this, but if I can't I'll bit the bullet.