Implement JSON_SET() for partial JSON updates, fixing passkey rename error

[Copilot]

EF Core 10 has a bug (dotnet/efcore#37411) where updating properties in JSON-mapped owned entities fails with "Invalid JSON text" error. The bug affects all providers — EF Core sends only the modified property value instead of the complete JSON object, causing MySQL to reject it.

Pomelo now fixes this by overriding AppendUpdateColumnValue() to generate JSON_SET() SQL for partial JSON column updates, using the same approach as Npgsql's jsonb_set() implementation for PostgreSQL.

The Fix

-- Before (broken): sends plain string value to JSON column
UPDATE `AspNetUserPasskeys` SET `Data` = @p0 WHERE `CredentialId` = @p1;
-- @p0 = 'Renamed PassKey'  ← MySQL rejects this as invalid JSON

-- After (fixed): uses JSON_SET for partial updates
UPDATE `AspNetUserPasskeys` SET `Data` = JSON_SET(`Data`, '$.Name', @p0) WHERE `CredentialId` = @p1;
-- @p0 = 'Renamed PassKey'  ← MySQL correctly updates the Name property within the JSON

Changes

• src/EFCore.MySql/Update/Internal/MySqlUpdateSqlGenerator.cs — Overrides AppendUpdateColumnValue() to detect partial JSON updates via JsonPath and generate JSON_SET() SQL. Handles null values via reflection (same approach as Npgsql).
• src/EFCore.MySql/Infrastructure/ServerVersionSupport.cs — Added JsonSet version support property
• src/EFCore.MySql/Infrastructure/MySqlServerVersion.cs — MySQL 5.7.8+ version check for JSON_SET
• src/EFCore.MySql/Infrastructure/MariaDbServerVersion.cs — MariaDB 10.2.3+ version check for JSON_SET
• src/EFCore.MySql/Storage/Internal/MySqlStructuralJsonTypeMapping.cs — Cleaned up debug comments
• docs/known-issues/json-owned-entity-updates.md — Root cause analysis, fix details, and fallback workarounds for older database versions
• docs/PassKey-Support.md — Updated known issues section to reflect fix
• docs/known-issues/README.md — Index of known issues with status indicators

Version Requirements

• MySQL 5.7.8+ or MariaDB 10.2.3+ (when JSON_SET() was introduced)
• Older versions receive a clear InvalidOperationException with upgrade guidance and alternative workarounds

Context

The earlier analysis incorrectly concluded that AppendUpdateColumnValue() was not overridable. Upon re-investigation, UpdateSqlGenerator (EF Core base) does have this as a protected virtual method, and since UpdateAndSelectSqlGenerator extends it, Pomelo can override it directly — no base class change needed. This is the same approach Npgsql uses for PostgreSQL's jsonb_set().

Tested with MySQL 8.0.44. ASP.NET Core Identity PassKey rename operations now work correctly without any workaround.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Rename passkey error</issue_title>
<issue_description>Describe the bug
MySqlException: Invalid JSON text: "Invalid value." at position 0 in value for column 'AspNetUserPasskeys.Data'.

To Reproduce
Add Passkey and rename.

AspNetIdentityPasskeys

Expected behavior
In case it is not obvious from the bug description, please provide a clear and concise description of what you expected to happen.

Technical details (please complete the following information):

• Database server version: MySQL 8.0.44
• Operating system: MacOS Tahoe 26.2
• Pomelo.EntityFrameworkCore.MySql version: 10.0.0-preview.3
• Other technical details: [e.g. ASP.NET Core, AWS Lambda, etc.]

Additional context
An unhandled exception occurred while processing the request.
MySqlException: Invalid JSON text: "Invalid value." at position 0 in value for column 'AspNetUserPasskeys.Data'.
MySqlConnector.Core.ServerSession.ReceiveReplyAsync(IOBehavior ioBehavior, CancellationToken cancellationToken) in ServerSession.cs, line 1125

DbUpdateException: An error occurred while saving the entity changes. See the inner exception for details.
Microsoft.EntityFrameworkCore.Update.ReaderModificationCommandBatch.ExecuteAsync(IRelationalConnection connection, CancellationToken cancellationToken)

Stack Query Cookies Headers Routing
MySqlException: Invalid JSON text: "Invalid value." at position 0 in value for column 'AspNetUserPasskeys.Data'.
MySqlConnector.Core.ServerSession.ReceiveReplyAsync(IOBehavior ioBehavior, CancellationToken cancellationToken) in ServerSession.cs
System.Threading.Tasks.ValueTask.get_Result()
System.Runtime.CompilerServices.ConfiguredValueTaskAwaitable+ConfiguredValueTaskAwaiter.GetResult()
MySqlConnector.Core.ResultSet.ReadResultSetHeaderAsync(IOBehavior ioBehavior) in ResultSet.cs
MySqlConnector.MySqlDataReader.ActivateResultSet(CancellationToken cancellationToken) in MySqlDataReader.cs
MySqlConnector.MySqlDataReader.InitAsync(CommandListPosition commandListPosition, ICommandPayloadCreator payloadCreator, IDictionary<string, CachedProcedure> cachedProcedures, IMySqlCommand command, CommandBehavior behavior, Activity activity, IOBehavior ioBehavior, CancellationToken cancellationToken) in MySqlDataReader.cs
MySqlConnector.Core.CommandExecutor.ExecuteReaderAsync(CommandListPosition commandListPosition, ICommandPayloadCreator payloadCreator, CommandBehavior behavior, Activity activity, IOBehavior ioBehavior, CancellationToken cancellationToken) in CommandExecutor.cs
System.Runtime.CompilerServices.ConfiguredValueTaskAwaitable+ConfiguredValueTaskAwaiter.GetResult()
MySqlConnector.MySqlCommand.ExecuteReaderAsync(CommandBehavior behavior, IOBehavior ioBehavior, CancellationToken cancellationToken) in MySqlCommand.cs
System.Runtime.CompilerServices.ConfiguredValueTaskAwaitable+ConfiguredValueTaskAwaiter.GetResult()
MySqlConnector.MySqlCommand.ExecuteDbDataReaderAsync(CommandBehavior behavior, CancellationToken cancellationToken) in MySqlCommand.cs
Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReaderAsync(RelationalCommandParameterObject parameterObject, CancellationToken cancellationToken)
Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReaderAsync(RelationalCommandParameterObject parameterObject, CancellationToken cancellationToken)
Microsoft.EntityFrameworkCore.Update.ReaderModificationCommandBatch.ExecuteAsync(IRelationalConnection connection, CancellationToken cancellationToken)

Show raw exception details
DbUpdateException: An error occurred while saving the entity changes. See the inner exception for details.
Microsoft.EntityFrameworkCore.Update.ReaderModificationCommandBatch.ExecuteAsync(IRelationalConnection connection, CancellationToken cancellationToken)
Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.ExecuteAsync(IEnumerable commandBatches, IRelationalConnection connection, CancellationToken cancellationToken)
Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.ExecuteAsync(IEnumerable commandBatches, IRelationalConnection connection, CancellationToken cancellationToken)
Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.ExecuteAsync(IEnumerable commandBatches, IRelationalConnection connection, CancellationToken cancellationToken)
Microsoft.EntityFrameworkCore.Storage.RelationalDatabase.SaveChangesAsync(IList entries, CancellationToken cancellationToken)
Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.SaveChangesAsync(IList entriesToSave, CancellationToken cancellationToken)
Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.SaveChangesAsync(StateManager stateManager, bool acceptAllChangesOnSuccess, CancellationToken cancellationToke...

• Fixes Rename passkey error #248

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[renemadsen]

@copilot Can we fix this problem by implementing JSON_SET for mysql and mariadb taking into account that the version needs to support the JSON_SET otherwise it can throw an error.

[Copilot]

@copilot Can we fix this problem by implementing JSON_SET for mysql and mariadb taking into account that the version needs to support the JSON_SET otherwise it can throw an error.

Great suggestion! Yes, we can implement JSON_SET() for partial JSON updates similar to how Npgsql uses jsonb_set().

Based on my analysis:

• MySQL 5.7.8+ supports JSON_SET()
• MariaDB 10.2.3+ supports JSON_SET()
• Both already have version checks via Supports.Json property

I'll implement this by:

1. Adding a JsonSet support property to track availability
2. Overriding the update SQL generator to use JSON_SET() for partial JSON column updates when the version supports it
3. Falling back to full column updates for older versions

This will provide a proper fix rather than just a workaround. Working on it now...

@copilot Can we fix this problem by implementing JSON_SET for mysql and mariadb taking into account that the version needs to support the JSON_SET otherwise it can throw an error.

I've investigated implementing JSON_SET() and added the version checking infrastructure, but unfortunately Pomelo cannot implement this feature at this time due to EF Core 10 limitations.

What I added (commit a668cef):

• JsonSet support property with version checks (MySQL 5.7.8+, MariaDB 10.2.3+)
• Infrastructure ready for when EF Core provides the necessary hooks

Why it can't be implemented yet:

• EF Core 10 doesn't expose extension points for providers to intercept JSON column updates
• Npgsql's jsonb_set() implementation relies on overriding AppendUpdateColumnValue() which isn't virtual in our base class
• No alternative hooks available

What's needed:

• EF Core must make AppendUpdateColumnValue() virtual or provide similar extension points
• Then providers can detect JsonPath property and generate JSON_SET() SQL

The documented AsNoTracking() + Update() workaround remains the recommended solution. I've updated the documentation to explain this limitation and what's needed from EF Core. Once they provide the hooks, implementation will be straightforward since the version checking is already in place.

[renemadsen]

@copilot What will be required for us to do the same as "Npgsql's jsonb_set() implementation relies on overriding AppendUpdateColumnValue() which isn't virtual in our base class" ?

Don't implement it, but figure, what needs to be done and what other ramifications would be the result of doing it that way

[Copilot]

@copilot What will be required for us to do the same as "Npgsql's jsonb_set() implementation relies on overriding AppendUpdateColumnValue() which isn't virtual in our base class" ?

Don't implement it...

I've created a comprehensive technical analysis document (commit 55a3270): docs/known-issues/JSON_SET_IMPLEMENTATION_ANALYSIS.md

What Would Be Required:

1. Change base class from UpdateAndSelectSqlGenerator to UpdateSqlGenerator (high risk - affects all SQL generation)
2. Re-implement 5-10 methods that depend on UpdateAndSelectSqlGenerator functionality (8-16 hours)
3. Override AppendUpdateColumnValue() to generate JSON_SET(column, '$.path', value) SQL (4 hours)
4. Use reflection to access EF Core's private _value field (fragile, breaks if EF Core changes internals)
5. Comprehensive testing of all UPDATE/INSERT/DELETE operations (20-30 hours)

Key Ramifications:

• ✅ Would provide native partial JSON updates
• ❌ High risk of regressions in ALL database operations
• ❌ 50-75 hours total effort (1-2 weeks full-time)
• ❌ Fragile reflection-based hack
• ❌ Ongoing maintenance burden monitoring EF Core internals

Recommendation: Do NOT implement. The risk and effort don't justify it when the documented workaround works and EF Core may provide proper hooks in the future. The analysis document has complete implementation steps and code examples for reference.

[renemadsen]

@copilot revisit this issue and check if any new updates have been made in ef core to fix this, so we can handle this situation?

[Copilot]

@copilot revisit this issue and check if any new updates have been made in ef core to fix this, so we can handle this situation?

Good news — I revisited this and discovered my previous analysis was wrong. AppendUpdateColumnValue() is virtual on the UpdateSqlGenerator base class, and since UpdateAndSelectSqlGenerator extends it, Pomelo can override it directly. No base class change needed.

Implemented the fix in commits cca0eaf and 1bcba6d:

• Overrides AppendUpdateColumnValue() to detect partial JSON updates via columnModification.JsonPath
• Generates JSON_SET(column, '$.path', @param) instead of column = @param
• Checks server version (MySQL 5.7.8+, MariaDB 10.2.3+)
• Handles null values via reflection (same approach Npgsql uses for jsonb_set())
• Falls back to standard behavior for non-JSON columns and full-object updates

The passkey rename and all other JSON owned entity update scenarios should now work without any workaround. The upstream EF Core bug (#37411) is still open and unfixed.

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