var ctx = new Entities();
            var Fields = ctx.ENTITIES_FEILDS.ToList();
            var assemblyBuilder = AppDomain.CurrentDomain.DefineDynamicAssembly(
                                    name: new AssemblyName("Demo"), access: AssemblyBuilderAccess.Run);

            var moduleBuilder = assemblyBuilder.DefineDynamicModule(name: "Module");

            var typeBuilder = moduleBuilder.DefineType(name: Fields.First(c => c.FEILD_ID == 1).ENTITIES.ENTITY_NAME, attr: TypeAttributes.Public);

            foreach (var item in Fields)
            {
                switch (item.FEILD_TYPE)
                {
                    case 0://int
                        {
                            var intField = typeBuilder.DefineField(fieldName: string.Format("_{0}", item.FEILD_NAME), type: typeof(string),
                                                  attributes: FieldAttributes.Private);

                            var intProperty = typeBuilder.DefineProperty(
                                                    name: item.FEILD_NAME,
                                                    attributes: PropertyAttributes.HasDefault,
                                                    returnType: typeof(string),
                                                    parameterTypes: null); // خاصیت پارامتر ورودی ندارد

                            //تعریف گت
                            var intpropertyGetMethod = typeBuilder.DefineMethod(
                                                                name: string.Format("get_{0}", item.FEILD_NAME),
                                                                attributes: MethodAttributes.Public |
                               MethodAttributes.SpecialName |
                                                                            MethodAttributes.HideBySig,
                                                                returnType: typeof(string),
                                                                parameterTypes: Type.EmptyTypes);

                            // اتصال گت متد به خاصیت عددی 
                            intProperty.SetGetMethod(intpropertyGetMethod);


                            //تعریف ست
                            var propertySetMethod =
                                typeBuilder.DefineMethod(name: string.Format("set_{0}", item.FEILD_NAME),
                                attributes: MethodAttributes.Public |
                               MethodAttributes.SpecialName |
                                                                            MethodAttributes.HideBySig,
                                                                  returnType: typeof(void),
                                                                parameterTypes: new[] { typeof(string) });
                            //اتصال ست متد 
                            intProperty.SetSetMethod(propertySetMethod);


                            // بدنه گت متد در اینجا تعریف خواهد شد
                            var propertyGetMethodIL = intpropertyGetMethod.GetILGenerator();
                            propertyGetMethodIL.Emit(OpCodes.Ldarg_0); // بارگذاری اشاره‌گری به وهله‌ای از کلاس جاری در پشته
                            propertyGetMethodIL.Emit(OpCodes.Ldfld, intField); // بارگذاری فیلد نام
                            propertyGetMethodIL.Emit(OpCodes.Ret);

                            //بدنه ست متد در اینجا تعریف شده است
                            var propertySetIL = propertySetMethod.GetILGenerator();
                            propertySetIL.Emit(OpCodes.Ldarg_0);
                            propertySetIL.Emit(OpCodes.Ldarg_1);
                            propertySetIL.Emit(OpCodes.Stfld, intField);
                            propertySetIL.Emit(OpCodes.Ret);

                        }

                        break;
                    case 1://string
                        {

                        } break;
                }

            }
            var t = typeBuilder.CreateType();



            var instance = Activator.CreateInstance(t);
           
            var type = instance.GetType();

            //تغییر مقدار یک خاصیت
            var setNameMethod = type.GetMethod("set_CoOrder");
            setNameMethod.Invoke(obj: instance, parameters: new[] {"1"});


            // دسترسی به خاصیت نام
            var nProperty = t.GetProperty("CoOrder");
            // و دریافت مقدار آن برای نمایش
            var result = nProperty.GetValue(instance, null);

            Console.WriteLine(result);


           
           
            Console.ReadKey();

public class Product
    {
        public int Id { get; set; }

        public string Name { get; set; }
    }

public class ProductService
    {
        public ProductService()
        {
            ListOfProducts = new List<Product>();
        }

        public List<Product> ListOfProducts
        {
            get;
            private set;
        }

        private void InitializeList( int toExclusive )
        {
            Parallel.For( 0 , toExclusive , ( int counter ) =>
            {
                ListOfProducts.Add( new Product()
                {
                    Id = counter ,
                    Name = "DefaultName" + counter.ToString()
                } );
            } );
        }

        public IAsyncResult BeginGetAll( AsyncCallback callback , object state )
        {
            var myTask = Task.Run<IEnumerable<Product>>( () =>
            {
                InitializeList( 100 );
                return ListOfProducts;
            } );
            return myTask.ContinueWith( x => callback( x ) );
        }

        public IEnumerable<Product> EndGetAll( IAsyncResult result )
        {
            return ( ( Task<IEnumerable<Product>> )result ).Result;
        }      
    }

class Program
    {
        static void Main( string[] args )
        {
            GetAllProducts().ToList().ForEach( ( Product item ) => 
            {
                Console.WriteLine( item.Name );
            } );

            Console.ReadLine();
        }

        public static IEnumerable<Product> GetAllProducts()
        {
            ProductService service = new ProductService();

            var output = Task.Factory.FromAsync<IEnumerable<Product>>( service.BeginGetAll , service.EndGetAll , TaskCreationOptions.None );
            return output.Result;            
        }
        
    }

 public async Task<IEnumerable<Product>> GetAllAsync()
        {
            var result = Task.Run( () =>
            {
                InitializeList( 100 );
                return ListOfProducts;
            } );
            return await result;
        }

class Program
    {
        static void Main( string[] args )
        {
            GetAllProducts().Result.ToList().ForEach( ( Product item ) => 
            {
                Console.WriteLine( item.Name );
            } );

            Console.ReadLine();
        }

        public static async Task<IEnumerable<Product>> GetAllProducts()
        {
            ProductService service = new ProductService();

            return await service.GetAllAsync();
        }
        
    }

• Filter : یک پراپرتی از نوع string است که درصورت مقداردهی آن، بر روی لیست خروجی ما عملیات فیلترینگ اعمال میشود. مثال :

Filter = "Name==Ali,Age>>10";

SortBy = "Age";

همانطور که در تصویر بالا مشاهده میکنید، برای اعمال فیلترینگ‌های پیچیده میتوانیم از چهار اپراتور , | ( )  استفاده کنیم. به همین جهت اگر نیاز داشتید که در مقدار جستجوی خود از این علائم استفاده کنید، باید قبل از هرکدام از آنها، علامت \ را اضافه کنید. 

 مثال رج‌اکس escape character در JavaScript  : 

let esc = (v) => v.replace(/([(),|])/g, '\\$1')

مثال #‍C : 

var value = "(test,test2)";
var esc = Regex.Replace(value, "([(),|])", "\\$1" ); // esc = \(test\,test2\)  

در بخش بعد با امکانات Mapper توکار Gridify و شخصی سازی آن آشنا خواهیم شد.

public class ValueModel
{
    [Required]
    [Display(Name = "Decimal Value")]
    public decimal DecimalValue { get; set; }

    [Required]
    [Display(Name = "Double Value")]
    public double DoubleValue { get; set; }

    [Required]
    [Display(Name = "Integer Value")]
    public int IntegerValue { get; set; }

    [Required]
    [Display(Name = "Date Value")]
    public DateTime DateValue { get; set; }
}

[HttpPost]
public ActionResult Index(ValueModel valueModel)
{
    if (ModelState.IsValid)
    {
        return Redirect("Index");
    }

    return View(valueModel);
}

<globalization culture="fa-IR" uiCulture="fa-IR" />

@using (Html.BeginForm())
{
    <ol>
        <li>
            @Html.LabelFor(m => m.DecimalValue)
            @Html.TextBoxFor(m => m.DecimalValue)
            @Html.ValidationMessageFor(m => m.DecimalValue)
        </li>
        <li>
            @Html.LabelFor(m => m.DoubleValue)
            @Html.TextBoxFor(m => m.DoubleValue)
            @Html.ValidationMessageFor(m => m.DoubleValue)
        </li>
        <li>
            @Html.LabelFor(m => m.IntegerValue)
            @Html.TextBoxFor(m => m.IntegerValue)
            @Html.ValidationMessageFor(m => m.IntegerValue)
        </li>
        <li>
            @Html.LabelFor(m => m.DateValue)
            @Html.TextBoxFor(m => m.DateValue)
            @Html.ValidationMessageFor(m => m.DateValue)
        </li>
        <li>
            <input type="submit" value="Submit"/>
        </li>
    </ol>
}

PM> Install-Package jquery-globalize

<script src="~/Scripts/jquery.validate.js"> </script>
<script src="~/Scripts/jquery.validate.unobtrusive.js"> </script>
<script src="~/Scripts/jquery.globalize/globalize.js"> </script>
<script src="~/Scripts/jquery.globalize/cultures/globalize.culture.fa-IR.js"> </script>

numberFormat: {
    pattern: ["n-"],
    ".": "/",
    currency: {
        pattern: ["$n-", "$ n"],
        ".": "/",
        symbol: "ریال"
    }
},

Globalize.culture('fa-IR');
$.validator.methods.number = function(value, element) {
    if (value.indexOf('.') > 0) {
        return false;
    }
    var splitedValue = value.split('/');
    if (splitedValue.length === 1) {
        return !isNaN(Globalize.parseInt(value));
    } else if (splitedValue.length === 2 && $.trim(splitedValue[1]).length === 0) {
        return false;
    }
    return !isNaN(Globalize.parseFloat(value));
};
};

Gregorian_Localized: {
    firstDay: 6,
    days: {
        names: ["یکشنبه", "دوشنبه", "سه شنبه", "چهارشنبه", "پنجشنبه", "جمعه", "شنبه"],
        namesAbbr: ["یکشنبه", "دوشنبه", "سه شنبه", "چهارشنبه", "پنجشنبه", "جمعه", "شنبه"],
        namesShort: ["ی", "د", "س", "چ", "پ", "ج", "ش"]
    },
    months: {
        names: ["ژانویه", "فوریه", "مارس", "آوریل", "می", "ژوئن", "ژوئیه", "اوت", "سپتامبر", "اُکتبر", "نوامبر", "دسامبر", ""],
        namesAbbr: ["ژانویه", "فوریه", "مارس", "آوریل", "می", "ژوئن", "ژوئیه", "اوت", "سپتامبر", "اُکتبر", "نوامبر", "دسامبر", ""]
    },
    AM: ["ق.ظ", "ق.ظ", "ق.ظ"],
    PM: ["ب.ظ", "ب.ظ", "ب.ظ"],
    patterns: {
        d: "yyyy/MM/dd",
        D: "yyyy/MM/dd",
        t: "hh:mm tt",
        T: "hh:mm:ss tt",
        f: "yyyy/MM/dd hh:mm tt",
        F: "yyyy/MM/dd hh:mm:ss tt",
        M: "dd MMMM"
    },
    JalaliDate: {
        g_days_in_month: [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31],
        j_days_in_month: [31, 31, 31, 31, 31, 31, 30, 30, 30, 30, 30, 29]
    },
    gregorianToJalali: function (gY, gM, gD) {
        gY = parseInt(gY);
        gM = parseInt(gM);
        gD = parseInt(gD);
        var gy = gY - 1600;
        var gm = gM - 1;
        var gd = gD - 1;

        var gDayNo = 365 * gy + parseInt((gy + 3) / 4) - parseInt((gy + 99) / 100) + parseInt((gy + 399) / 400);

        for (var i = 0; i < gm; ++i)
            gDayNo += Globalize.culture().calendars.Gregorian_Localized.JalaliDate.g_days_in_month[i];
        if (gm > 1 && ((gy % 4 == 0 && gy % 100 != 0) || (gy % 400 == 0)))
            /* leap and after Feb */
            ++gDayNo;
        gDayNo += gd;

        var jDayNo = gDayNo - 79;

        var jNp = parseInt(jDayNo / 12053);
        jDayNo %= 12053;

        var jy = 979 + 33 * jNp + 4 * parseInt(jDayNo / 1461);

        jDayNo %= 1461;

        if (jDayNo >= 366) {
            jy += parseInt((jDayNo - 1) / 365);
            jDayNo = (jDayNo - 1) % 365;
        }

        for (var i = 0; i < 11 && jDayNo >= Globalize.culture().calendars.Gregorian_Localized.JalaliDate.j_days_in_month[i]; ++i) {
            jDayNo -= Globalize.culture().calendars.Gregorian_Localized.JalaliDate.j_days_in_month[i];
        }
        var jm = i + 1;
        var jd = jDayNo + 1;

        return [jy, jm, jd];
    },
    jalaliToGregorian: function (jY, jM, jD) {
        jY = parseInt(jY);
        jM = parseInt(jM);
        jD = parseInt(jD);
        var jy = jY - 979;
        var jm = jM - 1;
        var jd = jD - 1;

        var jDayNo = 365 * jy + parseInt(jy / 33) * 8 + parseInt((jy % 33 + 3) / 4);
        for (var i = 0; i < jm; ++i) jDayNo += Globalize.culture().calendars.Gregorian_Localized.JalaliDate.j_days_in_month[i];

        jDayNo += jd;

        var gDayNo = jDayNo + 79;

        var gy = 1600 + 400 * parseInt(gDayNo / 146097); /* 146097 = 365*400 + 400/4 - 400/100 + 400/400 */
        gDayNo = gDayNo % 146097;

        var leap = true;
        if (gDayNo >= 36525) /* 36525 = 365*100 + 100/4 */ {
            gDayNo--;
            gy += 100 * parseInt(gDayNo / 36524); /* 36524 = 365*100 + 100/4 - 100/100 */
            gDayNo = gDayNo % 36524;

            if (gDayNo >= 365)
                gDayNo++;
            else
                leap = false;
        }

        gy += 4 * parseInt(gDayNo / 1461); /* 1461 = 365*4 + 4/4 */
        gDayNo %= 1461;

        if (gDayNo >= 366) {
            leap = false;

            gDayNo--;
            gy += parseInt(gDayNo / 365);
            gDayNo = gDayNo % 365;
        }

        for (var i = 0; gDayNo >= Globalize.culture().calendars.Gregorian_Localized.JalaliDate.g_days_in_month[i] + (i == 1 && leap) ; i++)
            gDayNo -= Globalize.culture().calendars.Gregorian_Localized.JalaliDate.g_days_in_month[i] + (i == 1 && leap);
        var gm = i + 1;
        var gd = gDayNo + 1;

        return [gy, gm, gd];
    },
    checkDate: function (jY, jM, jD) {
        return !(jY < 0 || jY > 32767 || jM < 1 || jM > 12 || jD < 1 || jD >
            (Globalize.culture().calendars.Gregorian_Localized.JalaliDate.j_days_in_month[jM - 1] + (jM == 12 && !((jY - 979) % 33 % 4))));
    },
    convert: function (value, format) {
        var day, month, year;

        var formatParts = format.split('/');
        var dateParts = value.split('/');
        if (formatParts.length !== 3 || dateParts.length !== 3) {
            return false;
        }

        for (var j = 0; j < formatParts.length; j++) {
            var currentFormat = formatParts[j];
            var currentDate = dateParts[j];
            switch (currentFormat) {
                case 'dd':
                    if (currentDate.length === 2 || currentDate.length === 1) {
                        day = currentDate;
                    } else {
                        year = currentDate;
                    }
                    break;
                case 'MM':
                    month = currentDate;
                    break;
                case 'yyyy':
                    if (currentDate.length === 4) {
                        year = currentDate;
                    } else {
                        day = currentDate;
                    }
                    break;
                default:
                    return false;
            }
        }

        year = parseInt(year);
        month = parseInt(month);
        day = parseInt(day);
        var isValidDate = Globalize.culture().calendars.Gregorian_Localized.checkDate(year, month, day);
        if (!isValidDate) {
            return false;
        }

        var grDate = Globalize.culture().calendars.Gregorian_Localized.jalaliToGregorian(year, month, day);
        var shDate = Globalize.culture().calendars.Gregorian_Localized.gregorianToJalali(grDate[0], grDate[1], grDate[2]);

        if (year === shDate[0] && month === shDate[1] && day === shDate[2]) {
            return true;
        }

        return false;
    }
},

$.validator.methods.date = function (value, element) {
    return Globalize.culture().calendars.Gregorian_Localized.convert(value, 'yyyy/MM/dd');
};

CREATE FUNCTION dbo.checkPerson(@data XML)
RETURNS BIT WITH SCHEMABINDING AS
BEGIN
   RETURN @data.exist('/people/person')
END
GO

CREATE TABLE tblXML
(
id INT PRIMARY KEY,
doc XML CHECK(dbo.checkPerson(doc)=1)  
)
GO

 INSERT INTO tblXML (id,  doc) VALUES
(
 1, '<people><person name="Vahid"/></people>'
)

INSERT INTO tblXML (id,  doc) VALUES
(
 2, '<people><emp name="Vahid"/></people>'
)

 The INSERT statement conflicted with the CHECK constraint "CK__tblXML__doc__060DEAE8".
The conflict occurred in database "testdb", table "dbo.tblXML", column 'doc'.
The statement has been terminated.

 CREATE TABLE xml_tab
(
 id INT IDENTITY PRIMARY KEY,
 xml_col  XML
)

 INSERT INTO xml_tab
VALUES ('<people><person name="Vahid"/></people>')
INSERT INTO xml_tab
VALUES ('<people><person name="Farid"/></people>')

 CREATE FUNCTION getIdValue(@doc XML)
RETURNS int WITH SCHEMABINDING AS
BEGIN
  RETURN @doc.value('/*[1]/@Id', 'int')
END

 CREATE TABLE docs_tab
(
id INT PRIMARY KEY,
doc XML,
CONSTRAINT id_chk CHECK(dbo.getIdValue(doc)=id)  
)

 INSERT INTO docs_tab (id,  doc) VALUES
(
 1, '<Invoice Id="1"/>'
)

INSERT INTO docs_tab (id,  doc) VALUES
(
 2, '<Invoice Id="1"/>'
)

 The INSERT statement conflicted with the CHECK constraint "id_chk".
The conflict occurred in database "testdb", table "dbo.docs_tab".
The statement has been terminated.

 CREATE TABLE Invoices
(
 doc XML,
 id AS dbo.getIdValue(doc) PERSISTED PRIMARY KEY
)

 INSERT INTO Invoices VALUES
(
 '<Invoice Id="1"/>'
)
INSERT INTO Invoices VALUES
(
 '<Invoice Id="1"/>'
)

 Violation of PRIMARY KEY constraint 'PK__Invoices__3213E83F145C0A3F'.
Cannot insert duplicate key in object 'dbo.Invoices'. The duplicate key value is (1).
The statement has been terminated.

 DECLARE @doc XML
SET @doc = '<foo bar="baz" />'
SELECT @doc.query('/foo/@bar')

 XQuery [query()]: Attribute may not appear outside of an element

 DECLARE @doc XML
SET @doc = '<foo bar="baz" />'
SELECT @doc.query('data(/foo/@bar)')

 DECLARE @x XML
SET @x = '<x>hello<y>world</y></x><x>again</x>'
SELECT @x.query('data(/*)')

 DECLARE @x XML
SET @x = '<x>hello<y>world</y></x><x>again</x>'
SELECT @x.query('string(/*)')

 XQuery [query()]: 'string()' requires a singleton (or empty sequence), found operand of type 'element(*,xdt:untyped) *'

 SELECT @x.query('string(/*[1])')

 SELECT @x.query('string(/)')

 DECLARE @x XML = '<age>12</age>'
SELECT @x.query('string(/age[1])')

 CREATE XML SCHEMA COLLECTION root_el AS
'<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
                  targetNamespace="urn:geo">
      <xs:element name="Root" type="xs:string" />    
</xs:schema>
'
GO

 DECLARE @xmlDoc XML
SET @xmlDoc = '<g:Root xmlns:g="urn:geo">datadata...</g:Root>'
SELECT @xmlDoc.query('
declare namespace g="urn:geo";
/g:Root/text()
')

 DECLARE @xmlDoc XML(root_el)
SET @xmlDoc = '<g:Root xmlns:g="urn:geo">datadata...</g:Root>'
SELECT @xmlDoc.query('
declare namespace g="urn:geo";
/g:Root[1]/text()
')

 XQuery [query()]: 'text()' is not supported on simple typed or 'http://www.w3.org/2001/XMLSchema#anyType'
elements, found 'element(g{urn:geo}:Root,xs:string) *'.

 DECLARE @xmlDoc XML(root_el)
SET @xmlDoc = '<g:Root xmlns:g="urn:geo">datadata...</g:Root>'
SELECT @xmlDoc.query('
declare namespace g="urn:geo";
data(/g:Root[1])
')

data(/age/text())

سپس یک کلاس جدید ساخته و با ارث بری از ActionFilterAttribute، کار ساخت فیلتر را آغاز میکنیم:

1. به صورت لیست
2. به صورت لیست sort شده براساس Name
3. فیلتر بر روی لیستی از فیلدهای موجود
4. این  لیست باید شامل تمامی داده‌های موجود (چه در رم و چه در دیتابیس) باشد.

    private static void GetLocalDestinationCount()
    {
        using (var context = new BreakAwayContext())
        {
            var count = context.Destinations.Local.Count;
            Console.WriteLine("Destinations in memory: {0}", count);
        }
    }

    private static void GetLocalDestinationCount()
    {
        using (var context = new BreakAwayContext())
        {
            foreach (var destination in context.Destinations)
            {
                Console.WriteLine(destination.Name);
            }
            var count = context.Destinations.Local.Count;
            Console.WriteLine("Destinations in memory: {0}", count);
        }
    }

    private static void GetLocalDestinationCountWithLoad()
    {
        using (var context = new BreakAwayContext())
        {
            context.Destinations.Load();
            var count = context.Destinations.Local.Count;
            Console.WriteLine("Destinations in memory: {0}", count);
        }
    }

    private static void LoadAustralianDestinations()
    {
        using (var context = new BreakAwayContext())
        {
            var query = from d in context.Destinations
                        where d.Country == "Australia"
                        select d;
            query.Load();
            var count = context.Destinations.Local.Count;
            Console.WriteLine("Aussie destinations in memory: {0}", count);
        }
    }

    private static void LocalLinqQueries()
    {
        using (var context = new BreakAwayContext())
        {
            context.Destinations.Load();
            var sortedDestinations = from d in context.Destinations.Local
                                     orderby d.Name
                                     select d;
            Console.WriteLine("All Destinations:");
            foreach (var destination in sortedDestinations)
            {
                Console.WriteLine(destination.Name);

            }
        }
        var aussieDestinations = from d in context.Destinations.Local
                                 where d.Country == "Australia"
                                 select d;
        Console.WriteLine();
        Console.WriteLine("Australian Destinations:");
        foreach (var destination in aussieDestinations)
        {
            Console.WriteLine(destination.Name);
        }
    }

تفاوت بین Linq provider‌های مختلف:

SELECT
    [Id], 
    (SELECT top 1  * FROM  [AppUsers] FOR XML auto),
    HASHBYTES ('SHA2_256', (SELECT top 1  * FROM  [AppUsers] FOR XML auto)) AS [hash] -- varbinary(n), since 2012
FROM
    [AppUsers]

using System.Collections.Generic;

namespace EFCoreRowIntegrity
{
    public interface IAuditableEntity
    {
        string Hash { set; get; }
    }

    public static class AuditableShadowProperties
    {
        public static readonly string CreatedDateTime = nameof(CreatedDateTime);
        public static readonly string ModifiedDateTime = nameof(ModifiedDateTime);
    }

    public class Blog : IAuditableEntity
    {
        public int BlogId { get; set; }
        public string Url { get; set; }

        public List<Post> Posts { get; set; }

        public string Hash { get; set; }
    }

    public class Post : IAuditableEntity
    {
        public int PostId { get; set; }
        public string Title { get; set; }
        public string Content { get; set; }

        public int BlogId { get; set; }
        public Blog Blog { get; set; }

        public string Hash { get; set; }
    }
}

using System.Collections.Generic;
using Microsoft.EntityFrameworkCore.ChangeTracking;

namespace EFCoreRowIntegrity
{
    public class AuditEntry
    {
        public EntityEntry EntityEntry { set; get; }
        public IList<AuditProperty> AuditProperties { set; get; } = new List<AuditProperty>();

        public AuditEntry() { }

        public AuditEntry(EntityEntry entry)
        {
            EntityEntry = entry;
        }
    }

    public class AuditProperty
    {
        public string Name { set; get; }
        public object Value { set; get; }

        public bool IsTemporary { set; get; }
        public PropertyEntry PropertyEntry { set; get; }

        public AuditProperty() { }

        public AuditProperty(string name, object value, bool isTemporary, PropertyEntry property)
        {
            Name = name;
            Value = value;
            IsTemporary = isTemporary;
            PropertyEntry = property;
        }
    }
}

using System;
using System.Collections.Generic;
using System.Security.Cryptography;
using System.Text;
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.ChangeTracking;
using Newtonsoft.Json;

namespace EFCoreRowIntegrity
{
    public static class HashingExtensions
    {
        public static string GenerateObjectHash(this object @object)
        {
            if (@object == null)
            {
                return string.Empty;
            }

            var jsonData = JsonConvert.SerializeObject(@object, Formatting.Indented);
            using (var hashAlgorithm = new SHA256CryptoServiceProvider())
            {
                var byteValue = Encoding.UTF8.GetBytes(jsonData);
                var byteHash = hashAlgorithm.ComputeHash(byteValue);
                return Convert.ToBase64String(byteHash);
            }
        }

        public static string GenerateEntityEntryHash(this EntityEntry entry, string propertyToIgnore)
        {
            var auditEntry = new Dictionary<string, object>();
            foreach (var property in entry.Properties)
            {
                var propertyName = property.Metadata.Name;
                if (propertyName == propertyToIgnore)
                {
                    continue;
                }
                auditEntry[propertyName] = property.CurrentValue;
            }
            return auditEntry.GenerateObjectHash();
        }

        public static string GenerateEntityHash<TEntity>(this DbContext context, TEntity entity, string propertyToIgnore)
        {
            return context.Entry(entity).GenerateEntityEntryHash(propertyToIgnore);
        }
    }
}

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.ChangeTracking;
using Microsoft.Extensions.Logging;

namespace EFCoreRowIntegrity
{
    public class BloggingContext : DbContext
    {
        public BloggingContext()
        { }

        public BloggingContext(DbContextOptions options)
            : base(options)
        { }

        public DbSet<Blog> Blogs { get; set; }
        public DbSet<Post> Posts { get; set; }

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            if (!optionsBuilder.IsConfigured)
            {
                optionsBuilder.EnableSensitiveDataLogging();
                var path = Path.Combine(Directory.GetCurrentDirectory(), "app_data", "EFCore.RowIntegrity.mdf");
                optionsBuilder.UseSqlServer($"Server=(localdb)\\mssqllocaldb;Database=EFCore.RowIntegrity;AttachDbFilename={path};Trusted_Connection=True;");
                optionsBuilder.UseLoggerFactory(new LoggerFactory().AddConsole((message, logLevel) =>
                logLevel == LogLevel.Debug &&
                           message.StartsWith("Microsoft.EntityFrameworkCore.Database.Command")));
            }
        }

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            base.OnModelCreating(modelBuilder);

            foreach (var entityType in modelBuilder.Model
                                                   .GetEntityTypes()
                                                   .Where(e => typeof(IAuditableEntity)
                                                   .IsAssignableFrom(e.ClrType)))
            {
                modelBuilder.Entity(entityType.ClrType)
                            .Property<DateTimeOffset?>(AuditableShadowProperties.CreatedDateTime);
                modelBuilder.Entity(entityType.ClrType)
                            .Property<DateTimeOffset?>(AuditableShadowProperties.ModifiedDateTime);
            }
        }

        public override int SaveChanges()
        {
            var auditEntries = OnBeforeSaveChanges();
            var result = base.SaveChanges();
            OnAfterSaveChanges(auditEntries);
            return result;
        }

        private IList<AuditEntry> OnBeforeSaveChanges()
        {
            var auditEntries = new List<AuditEntry>();

            foreach (var entry in ChangeTracker.Entries<IAuditableEntity>())
            {
                if (entry.State == EntityState.Detached || entry.State == EntityState.Unchanged)
                {
                    continue;
                }

                var auditEntry = new AuditEntry(entry);
                auditEntries.Add(auditEntry);

                var now = DateTimeOffset.UtcNow;

                foreach (var property in entry.Properties)
                {
                    var propertyName = property.Metadata.Name;
                    if (propertyName == nameof(IAuditableEntity.Hash))
                    {
                        continue;
                    }

                    if (property.IsTemporary)
                    {
                        // It's an auto-generated value and should be retrieved from the DB after calling the base.SaveChanges().
                        auditEntry.AuditProperties.Add(new AuditProperty(propertyName, null, true, property));
                        continue;
                    }

                    switch (entry.State)
                    {
                        case EntityState.Added:
                            entry.Property(AuditableShadowProperties.CreatedDateTime).CurrentValue = now;
                            auditEntry.AuditProperties.Add(new AuditProperty(propertyName, property.CurrentValue, false, property));
                            break;
                        case EntityState.Modified:
                            auditEntry.AuditProperties.Add(new AuditProperty(propertyName, property.CurrentValue, false, property));
                            entry.Property(AuditableShadowProperties.ModifiedDateTime).CurrentValue = now;
                            break;
                    }
                }
            }

            return auditEntries;
        }

        private void OnAfterSaveChanges(IList<AuditEntry> auditEntries)
        {
            foreach (var auditEntry in auditEntries)
            {
                foreach (var auditProperty in auditEntry.AuditProperties.Where(x => x.IsTemporary))
                {
                    // Now we have the auto-generated value from the DB.
                    auditProperty.Value = auditProperty.PropertyEntry.CurrentValue;
                    auditProperty.IsTemporary = false;
                }
                auditEntry.EntityEntry.Property(nameof(IAuditableEntity.Hash)).CurrentValue =
                    auditEntry.AuditProperties.ToDictionary(x => x.Name, x => x.Value).GenerateObjectHash();
            }
            base.SaveChanges();
        }
    }
}

public override int SaveChanges()
{
    var auditEntries = OnBeforeSaveChanges();
    var result = base.SaveChanges();
    OnAfterSaveChanges(auditEntries);
    return result;
}

if (property.IsTemporary)
{
   // It's an auto-generated value and should be retrieved from the DB after calling the base.SaveChanges().
   auditEntry.AuditProperties.Add(new AuditProperty(propertyName, null, true, property));
   continue;
}

private static void CheckRow1IsAuthentic()
{
    using (var context = new BloggingContext())
    {
        var blog1 = context.Blogs.Single(x => x.BlogId == 1);
        var entityHash = context.GenerateEntityHash(blog1, propertyToIgnore: nameof(IAuditableEntity.Hash));
        var dbRowHash = blog1.Hash;
        Console.WriteLine($"entityHash: {entityHash}\ndbRowHash:  {dbRowHash}");
        if (entityHash == dbRowHash)
        {
            Console.WriteLine("This row is authentic!");
        }
        else
        {
            Console.WriteLine("This row is tampered outside of the application!");
        }
    }
}

entityHash: P110cYquWpoaZuTpCWaqBn6HPSGdoQdmaAN05s1zYqo=
dbRowHash: P110cYquWpoaZuTpCWaqBn6HPSGdoQdmaAN05s1zYqo=
This row is authentic!

entityHash: tdiZhKMJRnROGLLam1WpldA0fy/CbjJaR2Y2jNU9izk=
dbRowHash: P110cYquWpoaZuTpCWaqBn6HPSGdoQdmaAN05s1zYqo=
This row is tampered outside of the application!

var blogs = (from blog in context.Blogs.ToList() // Note: this `ToList()` is necessary here for having Shadow properties values, otherwise they will considered `null`.
             let computedHash = context.GenerateEntityHash(blog, nameof(IAuditableEntity.Hash))
             select new
             {
               blog.BlogId,
               blog.Url,
               RowHash = blog.Hash,
               ComputedHash = computedHash,
               IsAuthentic = blog.Hash == computedHash
             }).ToList();