Mendapatkan Kod SQL daripada Entity Framework Core IQueryable

Tugas menjana kod SQL daripada IQueryable Entity Framework Core; objek memerlukan pendekatan yang sedikit berbeza dalam EF Core berbanding versi sebelumnya bagi Rangka Kerja Entiti.

EF Core 5/6 (Net 5/6)

Dalam EF Core 5 dan lebih baru, anda boleh menggunakan kaedah ToQueryString() untuk mendapatkan semula kod SQL:

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

Teras 2.1.2 dan Terdahulu

Untuk versi terdahulu EF Core (2.1.2 dan ke bawah), anda boleh menggunakan kaedah sambungan untuk tujuan ini:

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

In EF Core 3.0, kaedah sambungan berbeza diperlukan:

        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

Dalam EF Core 3.1, kaedah lanjutan lain diperlukan:

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);

Perlu diambil perhatian bahawa pasukan pembangunan menyedari pengehadan ini dan mempunyai rancangan untuk menanganinya dalam keluaran akan datang.

Atas ialah kandungan terperinci Bagaimanakah saya boleh mendapatkan kod SQL daripada IQueryable Teras Rangka Kerja Entiti?. Untuk maklumat lanjut, sila ikut artikel berkaitan lain di laman web China PHP!