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POHow to join with LinQ to (typed) dataset?
 

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  1. POHow to join with LinQ to (typed) dataset?
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    <p>i recently upgraded VS 2005 to 2010 and am fairly new to LinQ. Maybe somebody can put me in the right way. </p> <p><strong>Background</strong>: I have a typed dataset and have the standard SQLMembershipProvider extended with a Table AccessRule. So a role can have infinitely AccessRules(f.e. "Administrator" has "DeleteCustomer"). I use a custom membership provider that inherits from SqlMemberShipProvider and has an overloaded function hasAccess(one with a memory-dataset as parameter and the other uses the database directly).</p> <p>This is the complete Model:</p> <p><img src="https://i.stack.imgur.com/r2jcc.jpg" alt="enter image description here"></p> <p>Now i need to know f.e. if a User with UserID=<code>'89f9ea8d-8ae1-460b-a430-aa433261feec'</code> has AccessRule "DeleteCustomer". </p> <p>In SQL it would be something like this:</p> <pre><code>SELECT CASE WHEN aspnet_AccessRule.idAccessRule IS NULL THEN 0 ELSE 1 END AS Access FROM aspnet_RoleAccessRule INNER JOIN aspnet_AccessRule ON aspnet_RoleAccessRule.fiAccessRule = aspnet_AccessRule.idAccessRule INNER JOIN aspnet_Roles ON aspnet_RoleAccessRule.fiRole = aspnet_Roles.RoleId INNER JOIN aspnet_UsersInRoles ON aspnet_Roles.RoleId = aspnet_UsersInRoles.RoleId WHERE (aspnet_UsersInRoles.UserId = @UserID) AND (aspnet_AccessRule.RuleName =@RuleName) </code></pre> <p><strong>In short</strong>: </p> <p>how do i get from <code>aspnet_UsersInRoles</code> to<code>aspnet_AccessRule</code> with LinQ?</p> <p>Thank you in advance...</p> <p><strong>Edit</strong>:</p> <p>Although C# is also welcome, i'm preferring VB.Net.</p> <p>This is what i have, but it doesn't work. </p> <pre><code>Dim query = From accRule In dsAuth.aspnet_AccessRule _ From roleAccRule In dsAuth.aspnet_RoleAccessRule _ From role In dsAuth.aspnet_Roles _ From userRole In dsAuth.aspnet_UsersInRoles _ Where roleAccRule.fiAccessRule = accRule.idAccessRule _ And roleAccRule.fiRole = role.RoleId _ And userRole.RoleId = role.RoleId _ And userRole.UserId = userID And accRule.RuleName = accessRule Select accRule.idAccessRule Return query.Any </code></pre> <p>I get a <code>"Definition of method SelectMany is not accessible in this context"</code> compiler warning and the second<code>From</code> is highlighted. I assume it has something to do with the composite-keys in aspnet_RoleAccessRule and aspnet_UsersInRoles. Any suggestions?</p> <p>This gives the same exception on the first comma:</p> <pre><code>Dim query = From accRule In dsAuth.aspnet_AccessRule, _ roleAccRule In dsAuth.aspnet_RoleAccessRule, _ role In dsAuth.aspnet_Roles, _ userRole In dsAuth.aspnet_UsersInRoles _ Where accRule.idAccessRule = roleAccRule.fiAccessRule _ And roleAccRule.fiRole = role.RoleId _ And userRole.RoleId = role.RoleId _ And userRole.UserId = userID And accRule.RuleName = accessRule Select accRule.idAccessRule Return query.Any </code></pre> <p>This is the join syntax but with similar error(<code>Join</code> is not accessible in context..):</p> <pre><code>Dim userID As Guid = DirectCast(Membership.GetUser.ProviderUserKey, Guid) Dim query = From accRule In dsAuth.aspnet_AccessRule _ Join roleAccRule In dsAuth.aspnet_RoleAccessRule _ On accRule.idAccessRule Equals roleAccRule.fiAccessRule _ Join role In dsAuth.aspnet_Roles _ On role.RoleId Equals roleAccRule.fiRole _ Join userRole In dsAuth.aspnet_UsersInRoles _ On userRole.RoleId Equals role.RoleId _ Where userRole.UserId = userID And accRule.RuleName = accessRule Select accRule.idAccessRule Return query.Any </code></pre> <hr> <p><strong>Solution</strong>: I've forgotten to import the Namespace <code>System.LinQ</code>. All these queries are working.</p> <p>Side note: the Join-Syntax is by far the fastest query. Have a look at my followup-question: <a href="https://stackoverflow.com/questions/5551264/why-is-linq-join-so-much-faster-than-linking-with-where">Why is LINQ JOIN so much faster than linking with WHERE?</a></p>
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