= S3XRC Mini-Tutorial =

== Report Function for your Resource ==

=== The Idea ===

You have a module {{{xxx}}} and within it a resource {{{yyy}}}, which has a number of components. You're providing CRUD functions for the resource and its components using {{{shn_rest_controller()}}}.

Now you want to provide a reporting function for this resource, where the user can select records using a search form and then generate a summary report that can be exported in various formats, among others XLS, PDF and SVG.

This tutorial shows you how this can be integrated in the REST interface of your resource.

=== Creating a Custom Method Handler ===

First of all, implement your reporting function as a custom method handler. Add this function to your model file and add it as a method to your resource, like:

{{{
def shn_xxx_yyy_report(r, **attr):

    # Report generating code goes here

s3xrc.model.set_method("xxx", "yyy", method="report", action=shn_xxx_yyy_report)
}}}

A custom method handler has to take two arguments:

  - {{{r}}} is the respective S3Request object, which represents the current request
  - {{{attr}}} is the same dict of named arguments that have been passed to shn_rest_controller

Once you have done this, you can invoke your method handler from the URL:

{{{
http://localhost:8000/eden/xxx/yyy/report
}}}

The advantage of this is that this even understands URLs like:

{{{
http://localhost:8000/eden/xxx/yyy/1/report
http://localhost:8000/eden/xxx/yyy/report?yyy.id=1,2,3
http://localhost:8000/eden/xxx/yyy/report?yyy.field1__like=abc
}}}

meaning, it already implements a RESTful API for your reporting function, e.g. does the parsing/validating of the URL for you, implements the full range of URL queries for your resource and so forth. Nothing you need to care about now.

=== Providing different Report Formats ===

As mentioned before, you want to provide the report in various formats. To know which format has been requested, use r.representation:

{{{
def shn_xxx_yyy_report(r, **attr):

    if r.representation == "html":
        # HTML report generating code goes here

    elif r.representation == "xls":
        # XLS report generating code goes here

    elif r.representation == "pdf":
        # PDF report generating code goes here

    elif r.representation == "svg":
        # SVG report generating code goes here

    else:
        # Unsupported format
        raise HTTP(501, body=s3xrc.ERROR.BAD_FORMAT)

s3xrc.model.set_method("xxx", "yyy", method="report", action=shn_xxx_yyy_report)
}}}

Now your method handler recognises the requested format as specified in the URL by either a filename extension or the {{{format}}} variable:

{{{
http://localhost:8000/eden/xxx/yyy/4/report.xls
http://localhost:8000/eden/xxx/yyy.pdf/6
http://localhost:8000/eden/xxx/yyy/report?format=svg
}}}

=== How to get at the data ===

Now, how can you which data have to be processed by your reporting function and how can you get at them?

{{{r}}} (the {{{S3Request}}} object) contains the interface to the resource as an {{{S3Resource}}} object. And this is what you can use to access your data. Some examples:

{{{
def shn_xxx_yyy_report(r, **attr):

    resource = r.resource

    if r.representation == "html":

        # Get all records
        rows = resource.records()

    elif r.representation == "xls":

        # Access components record-wise:
        for record in resource:
            component_set = resource(record, component="component_name")
            for component_record in component_set:
                ...

    elif r.representation == "pdf":

        # Iterate through the records:
        for record in resource:
            ...

    elif r.representation == "svg":

        # Modifying the resource query before accessing records
        filter = resource.get_query()
        filter = filter & (db.xxx_yyy.field5 == "value")
        resource.build_query(filter = filter)

        # Iterate through the records:
        for record in resource:
            ...

    else:
        # Unsupported format
        raise HTTP(501, body=s3xrc.ERROR.BAD_FORMAT)

s3xrc.model.set_method("xxx", "yyy", method="report", action=shn_xxx_yyy_report)
}}}

...to be continued...