Deserialize into the shared C# model so master/detail bands render

Templates like report_3.frx use FastReport BusinessObjectDataSource with
nested datasources (e.g. abnormally_high_water_levels_report contains
abnormally_high). FastReport discovers the nested list by reflecting on
the C# type — register a flat DataTable and the inner band stays empty,
which is why customers saw 26-page PDFs with the master headers but no
detail rows.

Pull the report DTOs into the sidecar via cross-project Compile Include
from pwa_api/Modules/Report/Models, take a typeName field in the request,
deserialize JSON into the same concrete type, and call RegisterData with
the typed list — so reflection sees the same shape it always did.

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

Program.cs

@@ -1,16 +1,12 @@
-using System.Collections.Generic;
-using System.Data;
+using System.Collections;
+using System.Reflection;
 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(
@@ -18,15 +14,22 @@ var templateRoot = Path.Combine(
     builder.Configuration["TemplateRoot"] ?? "wwwroot");
 app.Logger.LogInformation("Template root: {TemplateRoot}", templateRoot);
 
+// Index every public type in this assembly by its short name so the JSON
+// payload can refer to a model class by name (e.g. "abnormal_meter_not_send_report").
+var typeIndex = Assembly.GetExecutingAssembly().GetTypes()
+    .Where(t => t.IsClass && t.IsPublic)
+    .ToDictionary(t => t.Name, t => t, StringComparer.Ordinal);
+
 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
+//   "template": "report_6",
 //   "dataSourceName": "abnormal_meter_not_send_report",
-//   "rows": [ { "field": "value", ... }, ... ],
-//   "fileName": "report.pdf"                       // optional, response Content-Disposition
+//   "typeName": "abnormal_meter_not_send_report",   // class in shared report models
+//   "rows": [ { ...same JSON as the C# object would serialize... } ],
+//   "fileName": "report.pdf"
 // }
 app.MapPost("/render", async (HttpRequest req) =>
 {
@@ -34,12 +37,11 @@ app.MapPost("/render", async (HttpRequest req) =>
     var bodyText = await sr.ReadToEndAsync();
     var body = JsonConvert.DeserializeObject<RenderRequest>(bodyText)
                ?? throw new ArgumentException("Empty body");
-    var pdf = RenderSingle(templateRoot, body);
+    var pdf = RenderSingle(templateRoot, body, typeIndex);
     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);
@@ -50,7 +52,7 @@ app.MapPost("/render/multi", async (HttpRequest req) =>
     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 streams = body.Sections.Select(s => new MemoryStream(RenderSingle(templateRoot, s, typeIndex))).ToList();
     var merged = MergePdfs(streams);
     foreach (var s in streams) s.Dispose();
     return Results.File(merged, "application/pdf", body.FileName ?? "merged.pdf");
@@ -61,7 +63,7 @@ return;
 
 // ---- helpers --------------------------------------------------------------
 
-static byte[] RenderSingle(string templateRoot, RenderRequest req)
+static byte[] RenderSingle(string templateRoot, RenderRequest req, Dictionary<string, Type> typeIndex)
 {
     if (string.IsNullOrWhiteSpace(req.Template))
         throw new ArgumentException("template is required");
@@ -73,18 +75,20 @@ static byte[] RenderSingle(string templateRoot, RenderRequest req)
     using var report = new Report();
     report.Load(path);
 
-    if (req.Rows != null && req.Rows.Count > 0)
+    if (req.Rows != null && !string.IsNullOrEmpty(req.TypeName))
     {
-        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);
+        if (!typeIndex.TryGetValue(req.TypeName, out var elementType))
+            throw new ArgumentException($"Unknown typeName: {req.TypeName}. Add the class to pwa_api/Modules/Report/Models/ so the sidecar can compile it in.");
+
+        var listType = typeof(List<>).MakeGenericType(elementType);
+        var typedList = (IList?)JsonConvert.DeserializeObject(req.Rows.ToString(), listType);
+        if (typedList == null)
+            throw new ArgumentException("Failed to deserialize rows.");
+
+        var dsName = req.DataSourceName ?? elementType.Name;
+        report.RegisterData((IEnumerable)typedList, dsName);
+        var ds = report.GetDataSource(dsName);
+        if (ds != null) ds.Enabled = true;
     }
 
     report.Prepare();
@@ -95,8 +99,6 @@ static byte[] RenderSingle(string templateRoot, RenderRequest req)
     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))
@@ -109,61 +111,7 @@ static string ResolveTemplatePath(string root, string name)
     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();
-    }
+    return inReports;
 }
 
 static byte[] MergePdfs(IEnumerable<MemoryStream> sources)
@@ -187,7 +135,8 @@ public class RenderRequest
 {
     public string Template { get; set; } = "";
     public string? DataSourceName { get; set; }
-    public JArray? Rows { get; set; }
+    public string? TypeName { get; set; }
+    public Newtonsoft.Json.Linq.JArray? Rows { get; set; }
     public string? FileName { get; set; }
 }
 

pwa_pdf_service.csproj

@@ -15,6 +15,13 @@
     <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
   </ItemGroup>
 
+  <!-- Share the report DTO classes with pwa_api so the sidecar deserializes
+       JSON into the same concrete types. FastReport reflects on those types
+       to find nested List<T> properties (master/detail bands). -->
+  <ItemGroup>
+    <Compile Include="..\pwa_api\Modules\Report\Models\report_*.cs" />
+  </ItemGroup>
+
   <ItemGroup>
     <!-- FastReport templates and fonts shared from main API -->
     <None Include="..\pwa_api\wwwroot\reports\**\*" Link="wwwroot\reports\%(RecursiveDir)%(Filename)%(Extension)">