You can only do this using a macro. You would attach the macro to the
Execute action event of the button. The routine needs to be modified for the internal name of your form & the specific name of the report to be generated. Here is the macro:
oDrawPage = ThisComponent.getDrawPage()
oForm = oDrawPage.Forms.getByName("YOUR_INTERNAL_FORM_NAME_HERE")
If oForm.IsNew then
ocontroller = Thisdatabasedocument.currentController
if not ocontroller.isconnected then ocontroller.connect
oreportdoc = Thisdatabasedocument.reportdocuments.getbyname("REPORT_NAME_HERE").open
This routine first updates or inserts the current record then executes the report.
If you are not familiar with macros you should refer to the LO documentation - found here.
To further help, attached is the sample I used for testing prior to posting the answer. This contains one table, query, form and report. The form contains the button which updates/inserts the table record and then executes the report.
Sample - ButtonToStartReport.odb
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