WeChat public platform developer-WeChat development, PHP variables in XML cannot be resolved

This is a text message returned to the XML, where the
$item _str
is dynamic, so need to introduce variables, but it seems that the variables can not be resolved, how to solve this problem ah?

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This is a text message returned to the XML, where the
$item _str
is dynamic, so need to introduce variables, but it seems that the variables can not be resolved, how to solve this problem ah?

Variables can be resolved, with sprintf can also be successful, the problem is in the previous variables, I passed in the object is not an array, so error, or more debugging more check ha

To be solved in a few ways, for example:

" . $item_str . "

