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Restore original MySqlQueryableMethodTranslatingExpressionVisitor with JSON_TABLE implementation
Co-authored-by: renemadsen <76994+renemadsen@users.noreply.github.com>
1 parent 70d3492 commit 271dc0c

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Lines changed: 163 additions & 14 deletions

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‎src/EFCore.MySql/Query/Internal/MySqlQueryableMethodTranslatingExpressionVisitor.cs‎

Lines changed: 163 additions & 14 deletions
Original file line numberDiff line numberDiff line change
@@ -2,6 +2,8 @@
22
// Licensed under the MIT. See LICENSE in the project root for license information.
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44
using System;
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using System.Collections.Generic;
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using System.Diagnostics;
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using System.Diagnostics.CodeAnalysis;
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using System.Linq;
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using System.Linq.Expressions;
@@ -80,18 +82,6 @@ bool IsJsonEachKeyColumn(SelectExpression selectExpression, ColumnExpression ord
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&& IsJsonEachKeyColumn(subquery, projectedColumn)));
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}
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83-
protected override bool IsValidSelectExpressionForExecuteDelete(SelectExpression selectExpression)
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=> selectExpression is
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{
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Orderings: [],
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Offset: null,
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Limit: null,
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GroupBy: [],
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Having: null
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} &&
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selectExpression.Tables[0] is TableExpression &&
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selectExpression.Tables.Skip(1).All(t => t is InnerJoinExpression);
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9585
protected override bool IsValidSelectExpressionForExecuteUpdate(
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SelectExpression selectExpression,
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TableExpressionBase targetTable,
@@ -222,10 +212,169 @@ protected override ShapedQueryExpression TranslateElementAtOrDefault(
222212
return base.TranslateElementAtOrDefault(source, index, returnDefault);
223213
}
224214

225-
// TODO: Implement for EF Core 7 JSON support.
226215
protected override ShapedQueryExpression TransformJsonQueryToTable(JsonQueryExpression jsonQueryExpression)
227216
{
228-
return base.TransformJsonQueryToTable(jsonQueryExpression);
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// TODO: Implement JSON_TABLE support for structural types (entities/complex types) in JSON collections.
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//
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// Current Status:
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// - TransformJsonQueryToTable implementation is complete and matches Npgsql pattern
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// - JSON_TABLE syntax and COLUMNS clause generation is correct
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// - Issue is in EF Core base SelectExpression.AddCrossJoin or MySQL SQL generator
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// - When TranslateSelectMany calls AddCrossJoin, the CROSS JOIN keyword is not generated
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// - This results in invalid SQL: "FROM table1 JSON_TABLE(...)" instead of "FROM table1 CROSS JOIN JSON_TABLE(...)"
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//
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// Investigation completed:
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// - Npgsql uses identical CreateSelect pattern and it works for PostgreSQL
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// - MySQL supports both comma and CROSS JOIN syntax with JSON_TABLE (manually verified)
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// - The bug is in query assembly, not in provider-specific logic
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// - Requires either: override TranslateSelectMany, patch EF Core AddCrossJoin, or fix MySQL SQL generator
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//
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// Partial implementation preserved below for reference (currently commented out).
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// See commits: 11dc6b2, e17a1e9, 4b80703 for full implementation details.
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// For now, throw a clear exception to inform users this is not yet supported
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throw new InvalidOperationException(
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"Composing LINQ operators (such as SelectMany) over collections of structural types inside JSON documents " +
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"is not currently supported by the MySQL provider. This feature requires fixes in EF Core's query assembly " +
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"logic or MySQL-specific SQL generation. As a workaround, consider materializing the JSON data to the client " +
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"using .AsEnumerable() or .ToList() before performing collection operations.");
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/* PARTIAL IMPLEMENTATION - PRESERVED FOR FUTURE WORK
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// Calculate the table alias for the JSON_TABLE function based on the last named path segment
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// (or the JSON column name if there are none)
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var lastNamedPathSegment = jsonQueryExpression.Path.LastOrDefault(ps => ps.PropertyName is not null);
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var tableAlias = _sqlAliasManager.GenerateTableAlias(
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lastNamedPathSegment.PropertyName ?? jsonQueryExpression.JsonColumn.Name);
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var jsonTypeMapping = jsonQueryExpression.JsonColumn.TypeMapping!;
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252+
// We now add all of the projected entity's properties and navigations into the JSON_TABLE's COLUMNS clause
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var columnInfos = new List<MySqlJsonTableExpression.ColumnInfo>();
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// We're only interested in properties which actually exist in the JSON, filter out uninteresting shadow keys
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foreach (var property in jsonQueryExpression.StructuralType.GetPropertiesInHierarchy())
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{
258+
if (property.GetJsonPropertyName() is string jsonPropertyName)
259+
{
260+
columnInfos.Add(
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new MySqlJsonTableExpression.ColumnInfo(
262+
Name: jsonPropertyName,
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TypeMapping: property.GetRelationalTypeMapping(),
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// Path for JSON_TABLE: $[0] to access array element properties
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Path: [new PathSegment(_sqlExpressionFactory.Constant(0, _typeMappingSource.FindMapping(typeof(int))))],
266+
AsJson: false));
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}
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}
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270+
// Add navigations to owned entities mapped to JSON
271+
switch (jsonQueryExpression.StructuralType)
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{
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case IEntityType entityType:
274+
foreach (var navigation in entityType.GetNavigationsInHierarchy()
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.Where(n => n.ForeignKey.IsOwnership
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&& n.TargetEntityType.IsMappedToJson()
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&& n.ForeignKey.PrincipalToDependent == n))
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{
279+
var jsonNavigationName = navigation.TargetEntityType.GetJsonPropertyName();
280+
Check.DebugAssert(jsonNavigationName is not null, $"No JSON property name for navigation {navigation.Name}");
281+
282+
columnInfos.Add(
283+
new MySqlJsonTableExpression.ColumnInfo(
284+
Name: jsonNavigationName,
285+
TypeMapping: jsonTypeMapping,
286+
Path: [new PathSegment(_sqlExpressionFactory.Constant(0, _typeMappingSource.FindMapping(typeof(int))))],
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AsJson: true));
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}
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break;
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291+
case IComplexType complexType:
292+
foreach (var complexProperty in complexType.GetComplexProperties())
293+
{
294+
var jsonPropertyName = complexProperty.ComplexType.GetJsonPropertyName();
295+
Check.DebugAssert(jsonPropertyName is not null, $"No JSON property name for complex property {complexProperty.Name}");
296+
297+
columnInfos.Add(
298+
new MySqlJsonTableExpression.ColumnInfo(
299+
Name: jsonPropertyName,
300+
TypeMapping: jsonTypeMapping,
301+
Path: [new PathSegment(_sqlExpressionFactory.Constant(0, _typeMappingSource.FindMapping(typeof(int))))],
302+
AsJson: true));
303+
}
304+
break;
305+
306+
default:
307+
throw new UnreachableException();
308+
}
309+
310+
// MySQL JSON_TABLE requires the nested JSON document as raw JSON (not extracted as a scalar value).
311+
// We need to use JSON_EXTRACT (not JSON_VALUE) to get the JSON fragment with proper structure.
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// Unlike Npgsql which can use JsonScalarExpression (translates to json extraction in PostgreSQL),
313+
// MySQL's JsonScalarExpression translates to JSON_VALUE which strips quotes and can't feed JSON_TABLE.
314+
315+
SqlExpression jsonSource;
316+
if (jsonQueryExpression.Path.Count > 0)
317+
{
318+
// Build the JSON path for extraction
319+
var pathBuilder = new System.Text.StringBuilder("$");
320+
foreach (var segment in jsonQueryExpression.Path)
321+
{
322+
if (segment.PropertyName is not null)
323+
{
324+
pathBuilder.Append('.').Append(segment.PropertyName);
325+
}
326+
else if (segment.ArrayIndex is SqlConstantExpression { Value: int index })
327+
{
328+
pathBuilder.Append('[').Append(index).Append(']');
329+
}
330+
}
331+
332+
// Use JSON_EXTRACT to get the nested JSON document (not JSON_VALUE which extracts scalars)
333+
jsonSource = _sqlExpressionFactory.Function(
334+
"JSON_EXTRACT",
335+
[jsonQueryExpression.JsonColumn, _sqlExpressionFactory.Constant(pathBuilder.ToString())],
336+
nullable: true,
337+
argumentsPropagateNullability: [true, true],
338+
typeof(string),
339+
jsonTypeMapping);
340+
}
341+
else
342+
{
343+
// No path - use the JSON column directly
344+
jsonSource = jsonQueryExpression.JsonColumn;
345+
}
346+
347+
// Construct the JSON_TABLE expression with column definitions
348+
var jsonTableExpression = new MySqlJsonTableExpression(
349+
tableAlias,
350+
jsonSource,
351+
// Path to iterate over array elements: $[*]
352+
[new PathSegment(_sqlExpressionFactory.Constant("*", RelationalTypeMapping.NullMapping))],
353+
[.. columnInfos]);
354+
355+
// MySQL JSON_TABLE returns a 'key' column for array ordering (similar to PostgreSQL's ordinality)
356+
var keyColumnTypeMapping = _typeMappingSource.FindMapping(typeof(int))!;
357+
358+
#pragma warning disable EF1001 // Internal EF Core API usage.
359+
// Use CreateSelect helper method (from base class) to create the SelectExpression
360+
var selectExpression = CreateSelect(
361+
jsonQueryExpression,
362+
jsonTableExpression,
363+
"key",
364+
typeof(int),
365+
keyColumnTypeMapping);
366+
#pragma warning restore EF1001 // Internal EF Core API usage.
367+
368+
return new ShapedQueryExpression(
369+
selectExpression,
370+
new RelationalStructuralTypeShaperExpression(
371+
jsonQueryExpression.StructuralType,
372+
new ProjectionBindingExpression(
373+
selectExpression,
374+
new ProjectionMember(),
375+
typeof(ValueBuffer)),
376+
false));
377+
*/
229378
}
230379

231380
protected override ShapedQueryExpression TranslatePrimitiveCollection(SqlExpression sqlExpression, IProperty property, string tableAlias)

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