Refactored service provider usage

- Remove service provider from WinForms altogether
- Moved service provider handling to processors

I18N Commander/Processor/SectionProcessor.cs

@@ -1,6 +1,7 @@
 using DataModel.Database;
 using DataModel.Database.Common;
 using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.DependencyInjection;
 
 namespace Processor;
 
@@ -9,16 +10,24 @@ public static class SectionProcessor
     /// <summary>
     /// Load one layer of the tree by using the specified depth:
     /// </summary>
-    public static IAsyncEnumerable<Section> LoadLayer(DataContext db, int depth)
+    public static async Task<List<Section>> LoadLayer(int depth)
     {
-        return db.Sections.Where(n => n.Depth == depth).OrderBy(n => n.Id).AsAsyncEnumerable();
+        await using var db = ProcessorMeta.ServiceProvider.GetRequiredService<DataContext>();
+        var sections = await db.Sections.Where(n => n.Depth == depth).OrderBy(n => n.Id).ToListAsync();
+        
+        // Ensure, that the database loaded the section's parent:
+        foreach (var section in sections)
+            await db.Entry(section).Reference(n => n.Parent).LoadAsync();
+
+        return sections;
     }
 
     /// <summary>
     /// Determine how deep the tree is.
     /// </summary>
-    public static async ValueTask<int> GetDepth(DataContext db)
+    public static async ValueTask<int> GetDepth()
     {
+        await using var db = ProcessorMeta.ServiceProvider.GetRequiredService<DataContext>();
         if(!await db.Sections.AnyAsync())
         {
             return 0;
@@ -30,8 +39,10 @@ public static class SectionProcessor
     /// <summary>
     /// Compute the new sections key and its depth, then store the section in the database.
     /// </summary>
-    public static async Task<ProcessorResult<Section>> AddSection(DataContext db, string text, string? parentKey)
+    public static async Task<ProcessorResult<Section>> AddSection(string text, string? parentKey)
     {
+        await using var db = ProcessorMeta.ServiceProvider.GetRequiredService<DataContext>();
+        
         // Remove any whitespaces from the section name, regardless of how many e.g. spaces the user typed:
         var key = string.Join('_', text.Split(' ', StringSplitOptions.TrimEntries | StringSplitOptions.RemoveEmptyEntries)).ToUpperInvariant();
         
@@ -97,24 +108,32 @@ public static class SectionProcessor
         }
     }
 
-    public static async Task RemoveSection(DataContext db, string selectedKey)
+    public static async Task RemoveSection(string selectedKey)
+    {
+        await using var db = ProcessorMeta.ServiceProvider.GetRequiredService<DataContext>();
+        await SectionProcessor.RemoveOneSectionAndItsChildren(db, selectedKey);
+        await db.SaveChangesAsync();
+    }
+
+    private static async Task RemoveOneSectionAndItsChildren(DataContext db, string selectedKey)
     {
         // Remove the section from the database:
         var section2Delete = await db.Sections.FirstOrDefaultAsync(n => n.DataKey == selectedKey);
         if (section2Delete is null)
             throw new ArgumentException($"The section with key {selectedKey} does not exist in the database.");
-        
+
         // Next, remove all children of the section, and the children's children, etc.:
         var children = await db.Sections.Where(n => n.Parent == section2Delete).ToListAsync();
         foreach (var child in children)
-            await RemoveSection(db, child.DataKey);
+            await SectionProcessor.RemoveOneSectionAndItsChildren(db, child.DataKey);
 
         db.Sections.Remove(section2Delete);
-        await db.SaveChangesAsync();
     }
-    
-    public static async Task<int> NumberChildren(DataContext db, string selectedKey)
+
+    public static async Task<int> NumberChildren(string selectedKey)
     {
+        await using var db = ProcessorMeta.ServiceProvider.GetRequiredService<DataContext>();
+        
         // Read the section from the database:
         var section = await db.Sections.FirstOrDefaultAsync(n => n.DataKey == selectedKey);
         if (section is null)
@@ -123,8 +142,10 @@ public static class SectionProcessor
         return await db.Sections.CountAsync(n => n.Parent == section);
     }
 
-    public static async Task<ProcessorResult<Section>> RenameSection(DataContext db, string selectedNodeKey, string alteredName)
+    public static async Task<ProcessorResult<Section>> RenameSection(string selectedNodeKey, string alteredName)
     {
+        await using var db = ProcessorMeta.ServiceProvider.GetRequiredService<DataContext>();
+        
         // Read the section from the database:
         var section = await db.Sections.FirstOrDefaultAsync(n => n.DataKey == selectedNodeKey);
         if (section is null)
@@ -158,10 +179,18 @@ public static class SectionProcessor
         }
     }
 
-    public static Section GetSection(DataContext db, string sectionKey) => db.Sections.First(n => n.DataKey == sectionKey);
-
-    public static async Task<string> GetSectionPath(DataContext db, string sectionKey)
+    public static async Task<Section> GetSection(string sectionKey)
     {
+        await using var db = ProcessorMeta.ServiceProvider.GetRequiredService<DataContext>();
+        var section = await db.Sections.FirstAsync(n => n.DataKey == sectionKey);
+        await db.Entry(section).Reference(n => n.Parent).LoadAsync();
+
+        return section;
+    }
+
+    public static async Task<string> GetSectionPath(string sectionKey)
+    {
+        await using var db = ProcessorMeta.ServiceProvider.GetRequiredService<DataContext>();
         var section = await db.Sections.FirstAsync(n => n.DataKey == sectionKey);
         
         // Ensure, that the database loaded the section's parent:

I18N Commander/Processor/TextElementProcessor.cs

@@ -1,18 +1,22 @@
 using DataModel.Database;
 using DataModel.Database.Common;
 using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.DependencyInjection;
 
 namespace Processor;
 
 public static class TextElementProcessor
 {
-    public static Task<IAsyncEnumerable<TextElement>> GetTextElements(DataContext db, Section section)
+    public static async Task<List<TextElement>> GetTextElements(Section section)
     {
-        return Task.FromResult(db.TextElements.Where(n => n.Section == section).AsAsyncEnumerable());
+        await using var db = ProcessorMeta.ServiceProvider.GetRequiredService<DataContext>();
+        return await db.TextElements.Where(n => n.Section == section).ToListAsync();
     }
 
-    public static async Task<ProcessorResult<TextElement>> AddTextElement(DataContext db, string? currentSectionKey, string elementName)
+    public static async Task<ProcessorResult<TextElement>> AddTextElement(string? currentSectionKey, string elementName)
     {
+        await using var db = ProcessorMeta.ServiceProvider.GetRequiredService<DataContext>();
+        
         if(string.IsNullOrWhiteSpace(currentSectionKey))
             throw new ArgumentOutOfRangeException(nameof(currentSectionKey));