Initial commit: FastReport PDF rendering sidecar

Tiny .NET 6 web app that accepts a JSON dataset and a FastReport template
name, renders to PDF, and returns the bytes. Exists because System.Drawing
is unsupported on .NET 8 Linux even with libgdiplus, but works on .NET 6
with `System.Drawing.EnableUnixSupport=true`. The main pwa_api (.NET 8)
calls this over loopback HTTP.

Endpoints:
  POST /render        single template, returns one PDF
  POST /render/multi  array of sections, merges into one PDF
  GET  /health        liveness probe

Templates and Fonts are sourced at build time from the sibling pwa_api
project so there's a single source of truth for .frx files.

Deployed as pwa-pdf-service.service on api.pwabilling.com, listening on
127.0.0.1:7082, self-contained (no system .NET 6 runtime needed).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitignore

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+bin/
+obj/
+publish/
+*.user
+*.suo
+.vs/
+.vscode/
+.idea/
+*.log

Program.cs

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+using System.Collections.Generic;
+using System.Data;
+using FastReport;
+using FastReport.Export.Pdf;
+using Microsoft.AspNetCore.Mvc;
+using Newtonsoft.Json;
+using Newtonsoft.Json.Linq;
+using PdfSharpCore.Pdf;
+using PdfSharpCore.Pdf.IO;
+
+var builder = WebApplication.CreateBuilder(args);
+builder.Services.AddEndpointsApiExplorer();
+
+var app = builder.Build();
+
+var templateRoot = Path.Combine(
+    AppContext.BaseDirectory,
+    builder.Configuration["TemplateRoot"] ?? "wwwroot");
+app.Logger.LogInformation("Template root: {TemplateRoot}", templateRoot);
+
+app.MapGet("/health", () => Results.Ok(new { status = "ok", time = DateTime.UtcNow }));
+
+// Render a single template + dataset to a PDF.
+// Body shape:
+// {
+//   "template": "report_6",                        // resolves to wwwroot/reports/report_6.frx
+//   "dataSourceName": "abnormal_meter_not_send_report",
+//   "rows": [ { "field": "value", ... }, ... ],
+//   "fileName": "report.pdf"                       // optional, response Content-Disposition
+// }
+app.MapPost("/render", async (HttpRequest req) =>
+{
+    using var sr = new StreamReader(req.Body);
+    var bodyText = await sr.ReadToEndAsync();
+    var body = JsonConvert.DeserializeObject<RenderRequest>(bodyText)
+               ?? throw new ArgumentException("Empty body");
+    var pdf = RenderSingle(templateRoot, body);
+    return Results.File(pdf, "application/pdf", body.FileName ?? $"{body.Template}.pdf");
+});
+
+// Render multiple sections and merge them into a single PDF.
+// Body shape: { "fileName": "merged.pdf", "sections": [ <RenderRequest>, ... ] }
+app.MapPost("/render/multi", async (HttpRequest req) =>
+{
+    using var sr = new StreamReader(req.Body);
+    var bodyText = await sr.ReadToEndAsync();
+    var body = JsonConvert.DeserializeObject<MultiRenderRequest>(bodyText)
+               ?? throw new ArgumentException("Empty body");
+
+    if (body.Sections == null || body.Sections.Count == 0)
+        return Results.BadRequest(new { error = "sections must contain at least one entry" });
+
+    var streams = body.Sections.Select(s => new MemoryStream(RenderSingle(templateRoot, s))).ToList();
+    var merged = MergePdfs(streams);
+    foreach (var s in streams) s.Dispose();
+    return Results.File(merged, "application/pdf", body.FileName ?? "merged.pdf");
+});
+
+app.Run();
+return;
+
+// ---- helpers --------------------------------------------------------------
+
+static byte[] RenderSingle(string templateRoot, RenderRequest req)
+{
+    if (string.IsNullOrWhiteSpace(req.Template))
+        throw new ArgumentException("template is required");
+
+    var path = ResolveTemplatePath(templateRoot, req.Template);
+    if (!File.Exists(path))
+        throw new FileNotFoundException($"Template not found: {req.Template}", path);
+
+    using var report = new Report();
+    report.Load(path);
+
+    if (req.Rows != null && req.Rows.Count > 0)
+    {
+        var dt = JArrayToDataTable(req.Rows, req.DataSourceName ?? "data");
+        report.RegisterData(dt, dt.TableName);
+        report.GetDataSource(dt.TableName).Enabled = true;
+    }
+    else if (!string.IsNullOrEmpty(req.DataSourceName))
+    {
+        // No rows but a name was given — register an empty table so the template
+        // renders its bands without the "data source not found" error.
+        var dt = new DataTable(req.DataSourceName);
+        report.RegisterData(dt, dt.TableName);
+    }
+
+    report.Prepare();
+
+    using var ms = new MemoryStream();
+    var pdfExport = new PDFExport();
+    report.Export(pdfExport, ms);
+    return ms.ToArray();
+}
+
+// Resolves "report_6" → wwwroot/reports/report_6.frx, with "documents/uuid"
+// supported for the empty-report templates that live under wwwroot/documents.
+static string ResolveTemplatePath(string root, string name)
+{
+    if (name.EndsWith(".frx", StringComparison.OrdinalIgnoreCase))
+    {
+        var direct = Path.Combine(root, name);
+        if (File.Exists(direct)) return direct;
+    }
+    var withExt = name.EndsWith(".frx") ? name : name + ".frx";
+    var inReports = Path.Combine(root, "reports", withExt);
+    if (File.Exists(inReports)) return inReports;
+    var inDocuments = Path.Combine(root, "documents", withExt);
+    if (File.Exists(inDocuments)) return inDocuments;
+    return inReports; // let RenderSingle throw a clean FileNotFoundException
+}
+
+// Build a DataTable whose columns are the union of keys present across the
+// JArray rows. FastReport binds .frx columns to DataTable columns by name.
+static DataTable JArrayToDataTable(JArray rows, string tableName)
+{
+    var dt = new DataTable(tableName);
+
+    foreach (var token in rows)
+    {
+        if (token is not JObject obj) continue;
+        foreach (var prop in obj.Properties())
+        {
+            if (dt.Columns.Contains(prop.Name)) continue;
+            dt.Columns.Add(prop.Name, InferColumnType(prop.Value));
+        }
+    }
+
+    foreach (var token in rows)
+    {
+        if (token is not JObject obj) continue;
+        var row = dt.NewRow();
+        foreach (DataColumn col in dt.Columns)
+        {
+            var jt = obj[col.ColumnName];
+            row[col.ColumnName] = JTokenToCell(jt, col.DataType);
+        }
+        dt.Rows.Add(row);
+    }
+    return dt;
+}
+
+static Type InferColumnType(JToken? value) => value?.Type switch
+{
+    JTokenType.Integer => typeof(long),
+    JTokenType.Float   => typeof(decimal),
+    JTokenType.Boolean => typeof(bool),
+    JTokenType.Date    => typeof(DateTime),
+    _                  => typeof(string),
+};
+
+static object JTokenToCell(JToken? jt, Type targetType)
+{
+    if (jt == null || jt.Type == JTokenType.Null || jt.Type == JTokenType.Undefined)
+        return DBNull.Value;
+    try
+    {
+        if (targetType == typeof(string)) return jt.ToString();
+        return jt.ToObject(targetType) ?? (object)DBNull.Value;
+    }
+    catch
+    {
+        return jt.ToString();
+    }
+}
+
+static byte[] MergePdfs(IEnumerable<MemoryStream> sources)
+{
+    using var output = new PdfDocument();
+    foreach (var src in sources)
+    {
+        src.Position = 0;
+        using var input = PdfReader.Open(src, PdfDocumentOpenMode.Import);
+        for (var i = 0; i < input.PageCount; i++)
+            output.AddPage(input.Pages[i]);
+    }
+    using var ms = new MemoryStream();
+    output.Save(ms, false);
+    return ms.ToArray();
+}
+
+// ---- DTOs -----------------------------------------------------------------
+
+public class RenderRequest
+{
+    public string Template { get; set; } = "";
+    public string? DataSourceName { get; set; }
+    public JArray? Rows { get; set; }
+    public string? FileName { get; set; }
+}
+
+public class MultiRenderRequest
+{
+    public string? FileName { get; set; }
+    public List<RenderRequest>? Sections { get; set; }
+}

Properties/launchSettings.json

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+{
+  "profiles": {
+    "pwa_pdf_service": {
+      "commandName": "Project",
+      "applicationUrl": "http://127.0.0.1:7082",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development"
+      }
+    }
+  }
+}

appsettings.json

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+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  },
+  "AllowedHosts": "*",
+  "TemplateRoot": "wwwroot"
+}

global.json

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+{
+  "sdk": {
+    "version": "6.0.428",
+    "rollForward": "latestFeature"
+  }
+}

nuget.config

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+<?xml version="1.0" encoding="utf-8"?>
+<configuration>
+    <packageSources>
+        <add key="nuget.org" value="https://api.nuget.org/v3/index.json" protocolVersion="3" />
+        <add key="71dev" value="https://nuget.71dev.com/v3/index.json" />
+    </packageSources>
+</configuration>

pwa_pdf_service.csproj

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+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <PropertyGroup>
+    <TargetFramework>net6.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <RootNamespace>pwa_pdf_service</RootNamespace>
+    <AssemblyName>pwa_pdf_service</AssemblyName>
+    <InvariantGlobalization>false</InvariantGlobalization>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="FastReport.Core" Version="2021.3.0" />
+    <PackageReference Include="PdfSharpCore" Version="1.3.65" />
+    <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <!-- FastReport templates and fonts shared from main API -->
+    <None Include="..\pwa_api\wwwroot\reports\**\*" Link="wwwroot\reports\%(RecursiveDir)%(Filename)%(Extension)">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
+    <None Include="..\pwa_api\wwwroot\documents\**\*" Link="wwwroot\documents\%(RecursiveDir)%(Filename)%(Extension)">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
+    <None Include="..\pwa_api\Fonts\**\*" Link="Fonts\%(RecursiveDir)%(Filename)%(Extension)">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
+  </ItemGroup>
+
+</Project>

runtimeconfig.template.json

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+{
+  "configProperties": {
+    "System.Drawing.EnableUnixSupport": true,
+    "System.GC.Server": true
+  }
+}