Bagaimana untuk Mendapatkan Kod SQL daripada Rangka Kerja Entiti Teras IQueryable?

Mendapatkan Kod SQL daripada Entiti Framework Core IQueryable

Kaedah ToTraceString Entiti Framework Core, yang menyediakan pembangun dengan kod SQL yang dijana oleh objek IQueryable, tidak tersedia dalam versi yang lebih baharu. Artikel ini meneroka kaedah alternatif untuk mendapatkan semula kod SQL dalam Teras Rangka Kerja Entiti, bergantung pada versi yang digunakan.

EF Core 5/6 (Net 5/6)

Dalam EF Core 5 dan 6 (Bersih 5 dan 6), kaedah ToQueryString tersedia untuk mendapatkan kod SQL untuk a pertanyaan:

var query = _context.Widgets.Where(w => w.IsReal && w.Id == 42);  
var sql = query.ToQueryString();

Teras 2.1.2

Untuk versi Net Core yang lebih lama, kaedah sambungan tersuai boleh digunakan:

using System.Linq;
using System.Reflection;
using Microsoft.EntityFrameworkCore.Query;
using Microsoft.EntityFrameworkCore.Query.Internal;
using Microsoft.EntityFrameworkCore.Query.Expressions;
using Microsoft.EntityFrameworkCore.Query.Sql;
using static Microsoft.EntityFrameworkCore.DbLoggerCategory;

public static class QueryableExtensions
{
        private static readonly TypeInfo QueryCompilerTypeInfo = typeof(QueryCompiler).GetTypeInfo();
    
        private static readonly FieldInfo QueryCompilerField = typeof(EntityQueryProvider).GetTypeInfo().DeclaredFields.First(x => x.Name == "_queryCompiler");
        private static readonly FieldInfo QueryModelGeneratorField = typeof(QueryCompiler).GetTypeInfo().DeclaredFields.First(x => x.Name == "_queryModelGenerator");
        private static readonly FieldInfo DataBaseField = QueryCompilerTypeInfo.DeclaredFields.Single(x => x.Name == "_database");
        private static readonly PropertyInfo DatabaseDependenciesField = typeof(Database).GetTypeInfo().DeclaredProperties.Single(x => x.Name == "Dependencies");
    
        public static string ToSql<TEntity>(this IQueryable<TEntity> query)
        {
            var queryCompiler = (QueryCompiler) QueryCompilerField.GetValue(query.Provider);
            var queryModelGenerator = (QueryModelGenerator)QueryModelGeneratorField.GetValue(queryCompiler);
            var queryModel = queryModelGenerator.ParseQuery(query.Expression);
            var database = DataBaseField.GetValue(queryCompiler);
            var databaseDependencies = (DatabaseDependencies) DatabaseDependenciesField.GetValue(database);
            var queryCompilationContext = databaseDependencies.QueryCompilationContextFactory.Create(false);
            var modelVisitor = (RelationalQueryModelVisitor) queryCompilationContext.CreateQueryModelVisitor();
            modelVisitor.CreateQueryExecutor<TEntity>(queryModel);
            var sql = modelVisitor.Queries.First().ToString();
    
            return sql;
        }
    }

EF Core 3.0

Dalam EF Core 3.0, kaedah sambungan berikut boleh digunakan:

        public static string ToSql<TEntity>(this IQueryable<TEntity> query)
        {
            using var enumerator = query.Provider.Execute<IEnumerable<TEntity>>(query.Expression).GetEnumerator();
            var enumeratorType = enumerator.GetType();
            var selectFieldInfo = enumeratorType.GetField(&quot;_selectExpression&quot;, BindingFlags.NonPublic | BindingFlags.Instance) ?? throw new InvalidOperationException($&quot;cannot find field _selectExpression on type {enumeratorType.Name}&quot;);
            var sqlGeneratorFieldInfo = enumeratorType.GetField(&quot;_querySqlGeneratorFactory&quot;, BindingFlags.NonPublic | BindingFlags.Instance) ?? throw new InvalidOperationException($&quot;cannot find field _querySqlGeneratorFactory on type {enumeratorType.Name}&quot;);
            var selectExpression = selectFieldInfo.GetValue(enumerator) as SelectExpression ?? throw new InvalidOperationException($&quot;could not get SelectExpression&quot;);
            var factory = sqlGeneratorFieldInfo.GetValue(enumerator) as IQuerySqlGeneratorFactory ?? throw new InvalidOperationException($&quot;could not get IQuerySqlGeneratorFactory&quot;);
            var sqlGenerator = factory.Create();
            var command = sqlGenerator.GetCommand(selectExpression);
            var sql = command.CommandText;
            return sql;
        }

EF Core 3.1

Akhir sekali, dalam EF Core 3.1, kod SQL boleh diperoleh menggunakan kaedah sambungan berikut:

using System.Linq;
using System.Reflection;
using System.Collections.Generic;
using Microsoft.EntityFrameworkCore.Query.SqlExpressions;
using Microsoft.EntityFrameworkCore.Query;

public static string ToSql<TEntity>(this IQueryable<TEntity> query) where TEntity : class
{
    using var enumerator = query.Provider.Execute<IEnumerable<TEntity>>(query.Expression).GetEnumerator();
    var relationalCommandCache = enumerator.Private(&quot;_relationalCommandCache&quot;);
    var selectExpression = relationalCommandCache.Private<SelectExpression>(&quot;_selectExpression&quot;);
    var factory = relationalCommandCache.Private<IQuerySqlGeneratorFactory>(&quot;_querySqlGeneratorFactory&quot;);

    var sqlGenerator = factory.Create();
    var command = sqlGenerator.GetCommand(selectExpression);

    string sql = command.CommandText;
    return sql;
}

private static object Private(this object obj, string privateField) => obj?.GetType().GetField(privateField, BindingFlags.Instance | BindingFlags.NonPublic)?.GetValue(obj);
private static T Private<T>(this object obj, string privateField) => (T)obj?.GetType().GetField(privateField, BindingFlags.Instance | BindingFlags.NonPublic)?.GetValue(obj);

Isu asas berkaitan dengan mendedahkan ToTraceString dalam Teras Rangka Kerja Entiti telah ditangani oleh pasukan EF dan dijangka akan diselesaikan pada masa hadapan lepaskan.

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