Report merge (#9532)

* Report merge

* Remove auto-generated file

* Remove pre-commit file

* Revert "Remove pre-commit file"

This reverts commit 00d80bae2a.

* Update API version

* Reduced duplicated logic

* reset pre-commit config

* Added migration files

* Added unit test

* Removed redundant migration

* Updated migration file

* Added a default report template with merge enabled

* Unit test to ensure a single page is generated

* Added docs to support merge feature

* Clean up

* Clean up

* Fixed unresolved link

* Updated API version

* Fixed test report path issue

* Add plugin context for each instance

* merge in master

* Fixed formating

* Added more detailed user guide

* Updated docs

* Added assert to ensure test html output exists

* Updated docs

* Fixed report test path

---------

Co-authored-by: Matthias Mair <code@mjmair.com>

docs/docs/api/schema.md

@@ -7,7 +7,7 @@ The API schema as documented below is generated using the [drf-spectactular](htt
 
 ## API Version
 
-This documentation is for API version: `339`
+This documentation is for API version: `352`
 
 !!! tip "API Schema History"
     We track API schema changes, and provide a snapshot of each API schema version in the [API schema repository](https://github.com/inventree/schema/).

docs/docs/report/context_variables.md

@@ -23,6 +23,28 @@ In addition to the [global context](#global-context), all *report* templates hav
 
 {{ report_context("base", "report") }}
 
+When using the `merge` context variable, the selected items are available in the `instances` list. {{ templatefile("report/inventree_stock_report_merge.html") }} shows a complete example. To access individual item attributes, you can either loop through the `instances` or access them by index like `instance.0.name`.
+
+Below is an example template that generates a single report for some selected parts. Each part occupies a row in the table
+
+```html
+{% raw %}
+<h2>Merged Report for Selected Parts</h2>
+<table>
+  <tr>
+    <th>Name</th>
+    <th>Description</th>
+  </tr>
+  {% for part in instances %}
+    <tr>
+      <td>{{ part.name }}</td>
+      <td>{{ part.description }}</td>
+    </tr>
+  {% endfor %}
+</table>
+{% endraw %}
+```
+
 Note that custom plugins may also add additional context variables to the report context.
 
 ::: report.models.ReportTemplate.get_context

docs/docs/report/report.md

@@ -44,3 +44,5 @@ For example, rendering the name of a part (which is available in the particular
 </p></i>
 {% endraw %}
 ```
+#### Rendering a single report vs. multiple report from selection
+Users can select multiple items such as `part`, `stockItem`,...etc to render from a report template. By default, the `merge` attribute of report template is disabled, which means an independent report will be generated for each item in the list of selected items. If `merge` is enabled, all selected items will be available in the `instances` context variable of the report template. Users are free to access them by indexing or in a loop. For more details, visit [context variable](./context_variables.md)

docs/docs/report/samples.md

@@ -22,6 +22,8 @@ The following report templates are provided "out of the box" and can be used as
 | [Sales Order Shipment](#sales-order-shipment) | [SalesOrderShipment](../sales/sales_order.md) | Sales Order Shipment report |
 | [Stock Location](#stock-location) | [StockLocation](../stock/index.md#stock-location) | Stock Location report |
 | [Test Report](#test-report) | [StockItem](../stock/index.md#stock-item) | Test Report |
+| [Selected Stock Items Report](#selected-stock-items-report) | [StockItem](../stock/index.md#stock-item) | Selected Stock Items report |
+
 
 ### Bill of Materials Report
 
@@ -55,6 +57,10 @@ The following report templates are provided "out of the box" and can be used as
 
 {{ templatefile("report/inventree_test_report.html") }}
 
+### Selected Stock Items Report
+
+{{ templatefile("report/inventree_stock_report_merge.html") }}
+
 ## Label Templates
 
 The following label templates are provided "out of the box" and can be used as a starting point, or as a reference for creating custom label templates: