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refactor(apphost): extract WithClearDatabaseCommand into MongoDbResourceBuilderExtensions #262

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Merged
mpaulosky merged 1 commit into from
May 8, 2026
Merged

refactor(apphost): extract WithClearDatabaseCommand into MongoDbResourceBuilderExtensions #262

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129 changes: 1 addition & 128 deletions src/AppHost/AppHost.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,11 +6,6 @@
//Solution Name : MyBlog
//Project Name : AppHost
//=======================================================
using Microsoft.Extensions.Diagnostics.HealthChecks;
using Microsoft.Extensions.Logging;

using MongoDB.Bson;
using MongoDB.Driver;

var builder = DistributedApplication.CreateBuilder(args);

Expand All @@ -19,129 +14,7 @@
var mongoDb = mongo.AddDatabase("myblog");
var redis = builder.AddRedis("redis");

// AC2 (#249): Semaphore prevents overlapping clear runs. A second concurrent invocation
// returns immediately with operator feedback instead of racing against the first.
var clearMutex = new SemaphoreSlim(1, 1);

// Expose the destructive clear-data action only during local runs (IsRunMode = false when publishing).
if (builder.ExecutionContext.IsRunMode)
{
mongo.WithCommand(
"clear-myblog-data",
"⚠️ Clear MyBlog Data",
executeCommand: async context =>
{
// AC2: Non-blocking acquire — return immediately if another clear is already in flight.
if (!await clearMutex.WaitAsync(0))
{
context.Logger.LogWarning(
"Clear MyBlog data skipped on {ResourceName} — a clear operation is already in progress.",
context.ResourceName);

return new ExecuteCommandResult
{
Success = false,
Message = "A clear operation is already in progress. Wait for the current run to finish, then try again."
};
}

try
{
context.Logger.LogWarning(
"Clear MyBlog data invoked on {ResourceName} — enumerating collections in 'myblog'.",
context.ResourceName);

var connectionString = await mongo.Resource.ConnectionStringExpression.GetValueAsync(context.CancellationToken);
if (connectionString is null)
{
context.Logger.LogError("Could not resolve MongoDB connection string for resource {ResourceName}.", context.ResourceName);
return new ExecuteCommandResult
{
Success = false,
Message = "Could not resolve MongoDB connection string. Is the MongoDB resource running?"
};
}

var client = new MongoClient(connectionString);
var database = client.GetDatabase("myblog");

var namesCursor = await database.ListCollectionNamesAsync(cancellationToken: context.CancellationToken);
var collectionNames = await namesCursor.ToListAsync(context.CancellationToken);

var results = new List<(string Name, long Deleted)>();
var warnings = new List<string>();

foreach (var name in collectionNames)
{
// Skip MongoDB internal system collections (e.g. system.views, system.users).
if (name.StartsWith("system.", StringComparison.OrdinalIgnoreCase))
continue;

try
{
// AC3 (#249): Best-effort per collection — errors are caught, logged as warnings,
// and the loop continues so remaining collections are still processed.
var collection = database.GetCollection<BsonDocument>(name);
var deleteResult = await collection.DeleteManyAsync(
FilterDefinition<BsonDocument>.Empty,
context.CancellationToken);

results.Add((name, deleteResult.DeletedCount));

context.Logger.LogInformation(
"Collection '{Collection}': {Count} document(s) deleted.",
name, deleteResult.DeletedCount);
}
catch (Exception ex) when (ex is not OperationCanceledException)
{
var warning = $"{name}: {ex.Message}";
warnings.Add(warning);
context.Logger.LogWarning(
ex,
"Collection '{Collection}' could not be cleared — skipping and continuing.",
name);
}
}

var totalDeleted = results.Sum(static r => r.Deleted);
var perCollection = results.Count == 0
? "no non-system collections found"
: string.Join("; ", results.Select(static r => $"{r.Name}: {r.Deleted}"));

context.Logger.LogWarning(
"Clear MyBlog data complete: {Total} document(s) removed across {Count} collection(s). Warnings: {WarnCount}.",
totalDeleted, results.Count, warnings.Count);

var message = $"{results.Count} collection(s) cleared — {totalDeleted} total document(s) deleted. ({perCollection})";
if (warnings.Count > 0)
message += $" ⚠️ {warnings.Count} collection(s) had errors: {string.Join("; ", warnings)}";

return new ExecuteCommandResult
{
Success = true,
Message = message
};
}
finally
{
clearMutex.Release();
}
},
new CommandOptions
{
Description = "Permanently deletes all data from the myblog database. Local development only.",
ConfirmationMessage = "This will permanently delete ALL data from the myblog database and cannot be undone. Confirm?",
IsHighlighted = true,
IconName = "DatabaseWarning",
// AC1 (#249): Gates only on the MongoDB resource's own health — intentionally does NOT
// check dependent resources (Web, etc.). Clearing is valid while the app is live against
// local Mongo; the Web app running is not a reason to disable the command.
UpdateState = ctx =>
ctx.ResourceSnapshot.HealthStatus == HealthStatus.Healthy
? ResourceCommandState.Enabled
: ResourceCommandState.Disabled
});
}
mongo.WithMongoDbDevCommands("myblog");

builder.AddProject<Projects.Web>("web")
.WithReference(mongoDb)
Expand Down
154 changes: 154 additions & 0 deletions src/AppHost/MongoDbResourceBuilderExtensions.cs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,154 @@
//=======================================================
//Copyright (c) 2026. All rights reserved.
//File Name : MongoDbResourceBuilderExtensions.cs
//Company : mpaulosky
//Author : Matthew Paulosky
//Solution Name : MyBlog
//Project Name : AppHost
//=======================================================

using Microsoft.Extensions.Diagnostics.HealthChecks;
using Microsoft.Extensions.Logging;

using MongoDB.Bson;
using MongoDB.Driver;

namespace Aspire.Hosting;

internal static class MongoDbResourceBuilderExtensions
{
// Shared semaphore — one per process; all commands share the same mutex.
private static readonly SemaphoreSlim _clearMutex = new(1, 1);

public static IResourceBuilder<MongoDBServerResource> WithMongoDbDevCommands(
this IResourceBuilder<MongoDBServerResource> builder,
string databaseName)
{
if (!builder.ApplicationBuilder.ExecutionContext.IsRunMode)
return builder;

builder.WithClearDatabaseCommand(databaseName);
return builder;
Comment on lines +20 to +31
}

private static void WithClearDatabaseCommand(
this IResourceBuilder<MongoDBServerResource> builder,
string databaseName)
{
builder.WithCommand(
"clear-myblog-data",
"⚠️ Clear MyBlog Data",
executeCommand: async context =>
{
// AC2: Non-blocking acquire — return immediately if another clear is already in flight.
Comment on lines +39 to +43
if (!await _clearMutex.WaitAsync(0))
{
context.Logger.LogWarning(
"Clear MyBlog data skipped on {ResourceName} — a clear operation is already in progress.",
context.ResourceName);

return new ExecuteCommandResult
{
Success = false,
Message = "A clear operation is already in progress. Wait for the current run to finish, then try again."
};
}

try
{
context.Logger.LogWarning(
"Clear MyBlog data invoked on {ResourceName} — enumerating collections in '{Database}'.",
context.ResourceName, databaseName);

var connectionString = await builder.Resource.ConnectionStringExpression.GetValueAsync(context.CancellationToken);
if (connectionString is null)
{
context.Logger.LogError("Could not resolve MongoDB connection string for resource {ResourceName}.", context.ResourceName);
return new ExecuteCommandResult
{
Success = false,
Message = "Could not resolve MongoDB connection string. Is the MongoDB resource running?"
};
}

var client = new MongoClient(connectionString);
var database = client.GetDatabase(databaseName);

var namesCursor = await database.ListCollectionNamesAsync(cancellationToken: context.CancellationToken);
var collectionNames = await namesCursor.ToListAsync(context.CancellationToken);

var results = new List<(string Name, long Deleted)>();
var warnings = new List<string>();

foreach (var name in collectionNames)
{
// Skip MongoDB internal system collections (e.g. system.views, system.users).
if (name.StartsWith("system.", StringComparison.OrdinalIgnoreCase))
continue;

try
{
// AC3 (#249): Best-effort per collection — errors are caught, logged as warnings,
// and the loop continues so remaining collections are still processed.
var collection = database.GetCollection<BsonDocument>(name);
var deleteResult = await collection.DeleteManyAsync(
FilterDefinition<BsonDocument>.Empty,
context.CancellationToken);

results.Add((name, deleteResult.DeletedCount));

context.Logger.LogInformation(
"Collection '{Collection}': {Count} document(s) deleted.",
name, deleteResult.DeletedCount);
}
catch (Exception ex) when (ex is not OperationCanceledException)
{
var warning = $"{name}: {ex.Message}";
warnings.Add(warning);
context.Logger.LogWarning(
ex,
"Collection '{Collection}' could not be cleared — skipping and continuing.",
name);
}
}

var totalDeleted = results.Sum(static r => r.Deleted);
var perCollection = results.Count == 0
? "no non-system collections found"
: string.Join("; ", results.Select(static r => $"{r.Name}: {r.Deleted}"));

context.Logger.LogWarning(
"Clear MyBlog data complete: {Total} document(s) removed across {Count} collection(s). Warnings: {WarnCount}.",
totalDeleted, results.Count, warnings.Count);

var message = $"{results.Count} collection(s) cleared — {totalDeleted} total document(s) deleted. ({perCollection})";
if (warnings.Count > 0)
message += $" ⚠️ {warnings.Count} collection(s) had errors: {string.Join("; ", warnings)}";

return new ExecuteCommandResult
{
Success = true,
Message = message
};
}
finally
{
_clearMutex.Release();
}
},
new CommandOptions
{
Description = "Permanently deletes all data from the myblog database. Local development only.",
ConfirmationMessage = "This will permanently delete ALL data from the myblog database and cannot be undone. Confirm?",
IsHighlighted = true,
IconName = "DatabaseWarning",
// AC1 (#249): Gates only on the MongoDB resource's own health — intentionally does NOT
// check dependent resources (Web, etc.). Clearing is valid while the app is live against
// local Mongo; the Web app running is not a reason to disable the command.
UpdateState = ctx =>
ctx.ResourceSnapshot.HealthStatus == HealthStatus.Healthy
? ResourceCommandState.Enabled
: ResourceCommandState.Disabled
});
}
}
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