Multiple subreports with beans

[maelan.desPrezdelamorlais_]

Hello reader,

I'm a bit new to jasper and was trying to do something, maybe not allowed.

I'm trying to print a report containing a List of ReportData, each ReportData containing some values and a collection of Beans printed in a subreport.

So what i wanted to do was putting my ReportData values in Detail Band, then (in detail band) a subreport to print my bean collection (and have it's own page number).

Here is a json exemple : 

[

{"FieldA":"Value","FieldB":[{"FieldB1":"Value","FieldB2":"Value","FieldB3":"Value",

"FieldB4":[{"FieldB4A":"value","FieldB4B":"value","FieldB4C":"value"},{"FieldB4A":"value","FieldB4B":"value","FieldB4C":"value"},{"FieldB4A":"value","FieldB4B":"value","FieldB4C":"value"}]},

{"FieldA":"Value","FieldB":[{"FieldB1":"Value","FieldB2":"Value","FieldB3":"Value",

"FieldB4":[{"FieldB4A":"value","FieldB4B":"value","FieldB4C":"value"},{"FieldB4A":"value","FieldB4B":"value","FieldB4C":"value"},{"FieldB4A":"value","FieldB4B":"value","FieldB4C":"value"}]},

{"FieldA":"Value","FieldB":[{"FieldB1":"Value","FieldB2":"Value","FieldB3":"Value",

"FieldB4":[{"FieldB4A":"value","FieldB4B":"value","FieldB4C":"value"},{"FieldB4A":"value","FieldB4B":"value","FieldB4C":"value"},{"FieldB4A":"value","FieldB4B":"value","FieldB4C":"value"}]}

]

I tried using "$P{REPORT_DATA_SOURCE}.subDataSource("FieldB4")" with and without cast (net.sf...JSonDataSource) as datasource expression.
It did'nt worked.
I tried to set my type as collection, list, and so on, to use "new net.sf...JRBeanCollectionDataSource($F{FieldB4})", but i got error saying it failed to read the field and convert it.
 

So, my question is, how should i declare/use my "FieldB" to get a dataSource from it for my subreport, with one occurence of the subReport by occurence of Detail Band?

Like That : 

FieldA : It's Value (the first one)

SubReport with first FieldB as dataSource (this subReport has a table wich explain why FieldB4 is a list)

Field A : It's Value (the second one)

SubReport with second FieldB as dataSource

And so on.

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Up ? - 21/10/2016