Some questions about the usage of 'items'

my task as below:
task3:
with:
items: <% ctx(result) %>
concurrency: 3
action: mysql.select connection=“mwc” query=“select count(1) from filesystem_tbl where hostname=<% item()[‘hostname’] %>”

item:
‘{u’‘app’’: u’‘mwc’’, u’‘hostname’’: u’‘test001’’, u’‘site’’: u’‘kwe’’, u’‘subapp’’: u’‘abc’’, u’‘instance’’: u’‘test0018:9101’’, u’‘job’’: u’‘abc’’, u’‘env’’: u’‘beta’’, u’‘name’’: u’‘node_cpu_used_percent’’}’

I want to get the value of hostname,but get some error as below:
‘YaqlEvaluationException: Unable to evaluate expression ‘’<% item()[’‘hostname’’] %>’’. NoMatchingFunctionException: No function “#indexer” matches supplied arguments’

how to fix it?

Try <% item().get(hostname) %>