fastreports/fastreport

1. This repository is a multi-project .NET reporting platform, not a single app. The center of the architecture is the FastReport engine plus a set of optional integrations, demos, and packaging tooling around it.

2. The core runtime is split into layered libraries:

- FastReport.Base holds the main report object model, bands, pages, data abstractions, engine, exports, preview, utilities, barcode/matrix/table/gauge objects, and script support.

- FastReport.OpenSource provides the open-source-specific surface area and platform adjustments.

- FastReport.Compat supplies compatibility shims for APIs that differ across .NET targets.

These layers separate the reusable report engine from target-specific concerns.

3. The main data flow in the library is: report template or report code -> report object model -> engine processes bands/data -> prepared pages -> preview/export. That pipeline is reflected in the Report, ReportEngine, PreparedPages, Preview, and Export areas.

4. Reports can be defined in several ways, and the repo supports all of them:

- template files such as .frx and .fpx

- XML-based report definitions

- report creation from code

The Demos/Reports folder and the code-based demos show how the same engine consumes different report inputs.

5. Data access is a major subsystem. FastReport.Base/Data contains core data-source abstractions for tables, views, parameters, relations, XML, CSV, JSON, and business objects. The Extras/Core/FastReport.Data/* projects extend that model with concrete connectors for databases and external stores such as SQL Server, MySQL, PostgreSQL, Oracle, SQLite, MongoDB, RavenDB, Couchbase, Elasticsearch, Cassandra, Firebird, ODBC, Excel, Google Sheets, and others.

6. The report engine itself is template-agnostic and datasource-agnostic. It receives registered data sources, resolves parameters and relations, executes scripting, and builds a prepared document. That separation is what allows the same engine to be reused in console apps, MVC/SPA apps, and desktop viewers.

7. Exporting is modular. FastReport.Base/Export contains shared export infrastructure and HTML/image export. Optional export plugins live under Extras/OpenSource/FastReport.OpenSource.Export.PdfSimple, which adds simple PDF generation without changing the core engine. The architecture is clearly plugin-oriented: the core prepares pages, then a selected exporter renders them into a target format.

8. The web stack is its own subsystem in FastReport.Core.Web. It provides:

- ASP.NET Core controllers for preview, export, print, dialogs, resources, and designer operations

- application services for report handling, exports, connections, text editing, and designer utilities

- web UI templates and static scripts/styles under FastReport.Web.Base

This layer adapts the core reporting engine to browser-based preview/designer workflows.

9. Several demo applications illustrate the supported deployment shapes:

- console apps for data binding, code-generated reports, user functions, and PDF export

- ASP.NET MVC samples for server-side rendering and database-backed reporting

- SPA samples with React, Vue, and Angular frontends talking to ASP.NET Core backends

- an Avalonia viewer sample in Demos/OpenSource/Extra

These demos are important because they show the integration boundary between host app, report engine, and data source.

10. There is a strong separation between reusable shared code and sample code. Demos/OpenSource/_Shared contains helper services used across demos, while the rest of Demos is mostly scenario-specific sample hosting. This keeps the demo apps thin and emphasizes the core library APIs.

11. The repository also includes testing and documentation infrastructure:

- Tools/FastReport.Tests.OpenSource for library tests

- Tools/FastReport.OpenSource.Documentation for DocFX-based docs

- Pack for build/package scripts and NuGet packaging metadata

These are supporting systems rather than runtime dependencies, but they define how the library is validated and distributed.

12. Resource and localization content is part of the product surface. FastReport/Resources contains built-in report samples, icons, styles, and report assets, while Localization stores translated UI strings. These resources feed the designer/runtime experience and are packaged with the library.

13. Architecturally, the repo is organized around extensibility points: new data connectors, exports, report objects, and web integrations can be added without rewriting the engine. The core engine stays small and reusable, while the extras/projects extend it through assemblies and plugins.