查看ef core 3.1/3.0/2.1.2生成的sql语句

• 对于EFCore 3.1

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

public static string ToSql(this IQueryable query) where TEntity : class
{
    var enumerator = query.Provider.Execute>(query.Expression).GetEnumerator();
    var relationalCommandCache = enumerator.Private("_relationalCommandCache");
    var selectExpression = relationalCommandCache.Private("_selectExpression");
    var factory = relationalCommandCache.Private("_querySqlGeneratorFactory");

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

　　

• 对于EFCore 3.0

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

　　

• 对于EFCore 2.1.2

static class IQueryableToSql
        {
            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 = QueryCompilerTypeInfo.DeclaredFields.First(x => x.Name == "_queryModelGenerator");
            private static readonly FieldInfo queryContextFactoryField = QueryCompilerTypeInfo.DeclaredFields.First(x => x.Name == "_queryContextFactory");
            private static readonly FieldInfo loggerField = QueryCompilerTypeInfo.DeclaredFields.First(x => x.Name == "_logger");
            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 sql, IReadOnlyDictionary parameters) ToSql(IQueryable query) where TEntity : class
            {
                var queryCompiler = (QueryCompiler)QueryCompilerField.GetValue(query.Provider);
                var queryContextFactory = (IQueryContextFactory)queryContextFactoryField.GetValue(queryCompiler);
                var logger = (Microsoft.EntityFrameworkCore.Diagnostics.IDiagnosticsLogger)loggerField.GetValue(queryCompiler);
                var queryContext = queryContextFactory.Create();
                var modelGenerator = (QueryModelGenerator)QueryModelGeneratorField.GetValue(queryCompiler);
                var newQueryExpression = modelGenerator.ExtractParameters(logger, query.Expression, queryContext);
                var queryModel = modelGenerator.ParseQuery(newQueryExpression);
                var database = (IDatabase)DataBaseField.GetValue(queryCompiler);
                var databaseDependencies = (DatabaseDependencies)DatabaseDependenciesField.GetValue(database);
                var queryCompilationContext = databaseDependencies.QueryCompilationContextFactory.Create(false);
                var modelVisitor = (RelationalQueryModelVisitor)queryCompilationContext.CreateQueryModelVisitor();

                modelVisitor.CreateQueryExecutor(queryModel);
                var command = modelVisitor.Queries.First().CreateDefaultQuerySqlGenerator()
                    .GenerateSql(queryContext.ParameterValues);

                return (command.CommandText, queryContext.ParameterValues);
            }
        }