Wie kann ich eine Linq-Abfrage in die Datenbank serialisieren?

Question

Ich brauche die Fähigkeit, eine Linq-Abfrage als String in der Datenbank speichern und dann laden und zu einem späteren Zeitpunkt ausführen.

Ich habe extreme Schwierigkeiten, meinen Kopf darum zu wickeln, wie man das macht.

fand ich diese Bibliothek, die sagt, es kann es tun: https://github.com/esskar/Serialize.Linq

Aber das Blog, dass die Dokumentation nach unten gehalten ist, und ich kann es nicht verstehen aus den Beispielen aus, zu viel passiert.

Kann mir jemand zeigen oder mich mit einem einfachen Beispiel für eine linq-Anweisung verbinden, die serialisiert und dann deserialisiert und ausgeführt wird?

Answer 1

Ich weiß nicht, ob dies die leistungsfähigste Option ist (ich bin mir nicht sicher, ob es gut oder schlecht ist), aber dies ist eine Option, um die gewünschte Funktionalität zu erreichen.

Die IQueryable ToString() Methode ermöglicht es Ihnen, die SQL, die das IQueryable-Objekt generieren und als die Datenbankabfrage ausführen wird, programmgesteuert abzurufen.

Dann können Sie diese SQL-Zeichenfolge in Entity Framework Raw SQL Abfragen verwenden.

In den folgenden Beispielen wird der standardmäßige Microsoft ASP.NET Identity DbContext verwendet.

IQueryable ToString() Beispiele:

ApplicationDbContext db = new ApplicationDbContext(); 
IQueryable query = db.Users.Where(w => w.Email != null); 
string generatedSql = query.ToString(); 

Der String generatedSql wird diese enthalten:

SELECT 
[Extent1].[Id] AS [Id], 
[Extent1].[Email] AS [Email], 
[Extent1].[EmailConfirmed] AS [EmailConfirmed], 
[Extent1].[PasswordHash] AS [PasswordHash], 
[Extent1].[SecurityStamp] AS [SecurityStamp], 
[Extent1].[PhoneNumber] AS [PhoneNumber], 
[Extent1].[PhoneNumberConfirmed] AS [PhoneNumberConfirmed], 
[Extent1].[TwoFactorEnabled] AS [TwoFactorEnabled], 
[Extent1].[LockoutEndDateUtc] AS [LockoutEndDateUtc], 
[Extent1].[LockoutEnabled] AS [LockoutEnabled], 
[Extent1].[AccessFailedCount] AS [AccessFailedCount], 
[Extent1].[UserName] AS [UserName] 
FROM [dbo].[AspNetUsers] AS [Extent1] 
WHERE [Extent1].[Email] IS NOT NULL 

Hier ist ein Beispiel der() Methode auf dem IQueryable Objekt umfassen die Verwendung zu zeigen, welche Art von SQL das wird generieren:

ApplicationDbContext db = new ApplicationDbContext(); 

IQueryable query = db.Users 
    .Include(i => i.Claims) 
    .Include(i => i.Roles) 
    .Where(w => w.Email != null); 

string generatedSql = query.ToString(); 

Nach dem Hinzufügen der Include-Methoden th e String generatedSql wird diese enthalten:

SELECT 
[UnionAll1].[AccessFailedCount] AS [C1], 
[UnionAll1].[Id] AS [C2], 
[UnionAll1].[Email] AS [C3], 
[UnionAll1].[EmailConfirmed] AS [C4], 
[UnionAll1].[PasswordHash] AS [C5], 
[UnionAll1].[SecurityStamp] AS [C6], 
[UnionAll1].[PhoneNumber] AS [C7], 
[UnionAll1].[PhoneNumberConfirmed] AS [C8], 
[UnionAll1].[TwoFactorEnabled] AS [C9], 
[UnionAll1].[LockoutEndDateUtc] AS [C10], 
[UnionAll1].[LockoutEnabled] AS [C11], 
[UnionAll1].[AccessFailedCount1] AS [C12], 
[UnionAll1].[UserName] AS [C13], 
[UnionAll1].[C1] AS [C14], 
[UnionAll1].[Id1] AS [C15], 
[UnionAll1].[UserId] AS [C16], 
[UnionAll1].[ClaimType] AS [C17], 
[UnionAll1].[ClaimValue] AS [C18], 
[UnionAll1].[C2] AS [C19], 
[UnionAll1].[C3] AS [C20], 
[UnionAll1].[C4] AS [C21] 
FROM (SELECT 
    CASE WHEN ([Extent2].[Id] IS NULL) THEN CAST(NULL AS int) ELSE 1 END AS [C1], 
    [Extent1].[AccessFailedCount] AS [AccessFailedCount], 
    [Extent1].[Id] AS [Id], 
    [Extent1].[Email] AS [Email], 
    [Extent1].[EmailConfirmed] AS [EmailConfirmed], 
    [Extent1].[PasswordHash] AS [PasswordHash], 
    [Extent1].[SecurityStamp] AS [SecurityStamp], 
    [Extent1].[PhoneNumber] AS [PhoneNumber], 
    [Extent1].[PhoneNumberConfirmed] AS [PhoneNumberConfirmed], 
    [Extent1].[TwoFactorEnabled] AS [TwoFactorEnabled], 
    [Extent1].[LockoutEndDateUtc] AS [LockoutEndDateUtc], 
    [Extent1].[LockoutEnabled] AS [LockoutEnabled], 
    [Extent1].[AccessFailedCount] AS [AccessFailedCount1], 
    [Extent1].[UserName] AS [UserName], 
    [Extent2].[Id] AS [Id1], 
    [Extent2].[UserId] AS [UserId], 
    [Extent2].[ClaimType] AS [ClaimType], 
    [Extent2].[ClaimValue] AS [ClaimValue], 
    CAST(NULL AS varchar(1)) AS [C2], 
    CAST(NULL AS varchar(1)) AS [C3], 
    CAST(NULL AS varchar(1)) AS [C4] 
    FROM [dbo].[AspNetUsers] AS [Extent1] 
    LEFT OUTER JOIN [dbo].[AspNetUserClaims] AS [Extent2] ON [Extent1].[Id] = [Extent2].[UserId] 
    WHERE [Extent1].[Email] IS NOT NULL 
UNION ALL 
    SELECT 
    2 AS [C1], 
    [Extent3].[AccessFailedCount] AS [AccessFailedCount], 
    [Extent3].[Id] AS [Id], 
    [Extent3].[Email] AS [Email], 
    [Extent3].[EmailConfirmed] AS [EmailConfirmed], 
    [Extent3].[PasswordHash] AS [PasswordHash], 
    [Extent3].[SecurityStamp] AS [SecurityStamp], 
    [Extent3].[PhoneNumber] AS [PhoneNumber], 
    [Extent3].[PhoneNumberConfirmed] AS [PhoneNumberConfirmed], 
    [Extent3].[TwoFactorEnabled] AS [TwoFactorEnabled], 
    [Extent3].[LockoutEndDateUtc] AS [LockoutEndDateUtc], 
    [Extent3].[LockoutEnabled] AS [LockoutEnabled], 
    [Extent3].[AccessFailedCount] AS [AccessFailedCount1], 
    [Extent3].[UserName] AS [UserName], 
    CAST(NULL AS int) AS [C2], 
    CAST(NULL AS varchar(1)) AS [C3], 
    CAST(NULL AS varchar(1)) AS [C4], 
    CAST(NULL AS varchar(1)) AS [C5], 
    [Extent4].[UserId] AS [UserId], 
    [Extent4].[RoleId] AS [RoleId], 
    [Extent4].[UserId] AS [UserId1] 
    FROM [dbo].[AspNetUsers] AS [Extent3] 
    INNER JOIN [dbo].[AspNetUserRoles] AS [Extent4] ON [Extent3].[Id] = [Extent4].[UserId] 
    WHERE [Extent3].[Email] IS NOT NULL) AS [UnionAll1] 
ORDER BY [UnionAll1].[Id] ASC, [UnionAll1].[C1] ASC 

---

Dann können Sie diese SQL-Abfragen speichern, wie Sie wollen, und wenn Sie bereit sind, sie laufen Sie Entity Framework Raw SQL-Abfragen verwenden können.

So:

ApplicationDbContext db = new ApplicationDbContext(); 
var users = db.Users.SqlQuery("Your SQL here"); 


//or this if you need your DbSet to be dynamic 
ApplicationDbContext db = new ApplicationDbContext(); 
var users = db.Set<User>.SqlQuery("Your SQL here"); 


//or this for commands 
ApplicationDbContext db = new ApplicationDbContext(); 
db.Database.ExecuteSqlCommand("Your SQL command string here");