Where can I find document for how to implement the GenerateID() interface?
Printed From: IdeaBlade
Category: DevForce
Forum Name: DevForce 2009
Forum Discription: For .NET 3.5
URL: http://www.ideablade.com/forum/forum_posts.asp?TID=1436
Printed Date: 05-Jun-2024 at 11:28am
Topic: Where can I find document for how to implement the GenerateID() interface?
Posted By: Suah
Subject: Where can I find document for how to implement the GenerateID() interface?
Date Posted: 20-Aug-2009 at 9:52pm
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Where can I find document for how to implement the GenerateID() interface?
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Replies:
Posted By: GregD
Date Posted: 24-Aug-2009 at 4:13pm
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There are a couple of mentions of IIDGenerator in the Developer Guide, which describe at a high level what it does. Other than that, there is a sample implementation (NumericIDGenerator) included in the C:\Program Files\IdeaBlade DevForce\Samples.
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Posted By: dpollot44
Date Posted: 13-Jan-2010 at 8:52am
I'm evaluating the software (universal) and that directory does not exist for me. There are three sub-folders; Documentation, Learning Resources, and SilverLight Assemblies... I would have thought perhaps either of the first two might contain the sample implementations but nope.
Is the code posted somewhere (saving me the time of re-downloading/registering)
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Posted By: GregD
Date Posted: 13-Jan-2010 at 11:19am
Between August and now, the Learning Resources were reorganized and the sample implementation of IidGenerator was moved to the following location:
LearningResources\040_BusObjPersistence\AddingDeleting\Snippets\NumericIdGenerator
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Posted By: dpollot44
Date Posted: 13-Jan-2010 at 12:14pm
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I forgot to mention that the "LearningResources" folder is empty for me (I had tried to do a quick search for the .cs file and it would have found it there otherwise). Do I just need to re-download and extract? Perhaps a different version?
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Posted By: dpollot44
Date Posted: 13-Jan-2010 at 12:35pm
I reinstalled. The full/vs. custom install didn't include the learning units.
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Posted By: dpollot44
Date Posted: 13-Jan-2010 at 1:00pm
...And I spoke too soon. I've reinstalled a couple of times and the learning folder is empty each time. Can someone just post the sample code (specifically looking for NumericIdGenerator).
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Posted By: davidklitzke
Date Posted: 13-Jan-2010 at 2:26pm
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I have seen some rare cases where the Learning Resources get installed to C:\MyTutorials or D:\MyTutorials (or some other drive:\MyTutorials). I think if you look hard enough, you can find the Learning Resources. It is extremely rare for the Learning Resources not to get installed somewhere on your hard drive.
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Posted By: GregD
Date Posted: 13-Jan-2010 at 5:18pm
/* A sample IIdGenerator implementation.
*
* You can use this as-is (almost) or modify as needed. This is provided as a sample only.
*
* You may want to use an IIdGenerator to generate both temporary and real Id values for
* key fields of your Entities. Note that for tables using keys based on identity or sequence/serial
* values the StoreGeneratedIdGenerator provided by the DevForce framework should be sufficient.
*
* Possible customizations -
* - change the namespace
* - change the class name
* - alter IsApplicable() logic for your data source key
* - alter GetNextTempId() logic for custom temporary Id values
* - alter GetReadIdMap() logic for custom real Id allocation
*
* Place your IdGenerator class in an assembly which can be deployed on both client and server.
*
* If you implement a custom IIdGenerator, place the assembly name in either the
* ProbeAssemblyNames for a given data source key or the ProbeAssemblyNames
* at the root of the IdeaBlade Configuration file.
*
*/
using System;
using System.Data;
using System.Runtime.Serialization;
using IdeaBlade.Ado;
using IdeaBlade.Core;
using IdeaBlade.EntityModel;
namespace IdeaBladeTest1Model {
/// <summary>
/// Sample IIdGenerator implementation. The class should be marked with the Serializable
/// or DataContract attribute if you plan to save and restore the EntityCache to/from files.
/// </summary>
[DataContract]
public class NumericIdGenerator : IIdGenerator {
/// <summary>
/// An instance of the IIdGenerator will be instantiated by the DevForce framework
/// on both the client and server. A public parameterless constructor is required.
/// </summary>
public NumericIdGenerator() {
}
/// <summary>
/// Return true if this IIdGenerator should be used with the specified key.
/// </summary>
/// <remarks>
/// In this example we test the key name, but this is for illustration only. Be sure to
/// change this code for your implementation. If you require an IdGenerator but DevForce
/// can't find an "applicable" one, an exception is thrown. Called on both client and server.
/// </remarks>
public bool IsApplicable(IDataSourceKey dataSourceKey) {
return dataSourceKey.Name.StartsWith("IdeaBladeTest1");
}
/// <summary>
/// Called by DevForce on the client to retrieve a temporary Id value for the specified column.
/// </summary>
/// <remarks>
/// This example returns negative values starting at -1. If you need custom temporary Ids then
/// change this logic as necessary.
/// Be sure to store all temporary Ids. The framework will request them in the <see cref="TempIds"/>
/// property.
/// </remarks>
public object GetNextTempId(DataEntityProperty entityColumn) {
Object id;
_nextBaseId++;
long longId = (long) (-1 * _nextBaseId);
try {
id = Convert.ChangeType(longId, entityColumn.DataType);
} catch {
throw new NotSupportedException("This id generator cannot generate ids of type " + entityColumn.DataType);
}
_tempIds.Add(new UniqueId(entityColumn, id));
return id;
}
/// <summary>
/// Called by DevForce on the client to retrieve a collection of the temporary Id values generated since
/// the last <see cref="Reset"/> call.
/// </summary>
/// <remarks>
/// Be sure to maintain the collection of temporary Ids generated in <see cref="GetNextTempId"/>.
/// </remarks>
public UniqueIdCollection TempIds {
get { return _tempIds; }
}
/// <summary>
/// Return whether the specified Id is a temporary Id generated by this IdGenerator.
/// </summary>
/// <remarks>
/// DevForce will call this on the client to test whether the specified Id is temporary and will require
/// "fixup" as a real id.
/// </remarks>
public bool IsTempId(UniqueId uniqueId) {
if (_tempIds == null) {
return false;
}
return _tempIds.Contains(uniqueId);
}
/// <summary>
/// Called by DevForce after an EntityManager.SaveChanges call is performed and all temporary Id values
/// have been "fixed up" as real Ids. Use this to clear your temporary Id collection and reset counters.
/// </summary>
public void Reset() {
_tempIds.Clear();
_nextBaseId = 0;
}
/// <summary>
/// Called by DevForce from the BOS to retrieve "real" Id values for the temporary Ids passed.
/// </summary>
/// <remarks>
/// You can retrieve "real" Ids in any manner you like - this sample shows allocation
/// of Ids from a single table holding a global sequence value.
/// You must return a UniqueIdMap from this method containing a real Id value for each
/// temporary Id. Note that the UniqueId objects passed in contain information on the
/// EntityColumn used. You can use this information to perform more complex Id allocation
/// if needed.
/// Because this method is called from the server, and the server is multi-threaded,
/// you must provide synchronization logic to handle concurrent requests. In this
/// sample, a lock is used within the GetNextId logic.
/// </remarks>
public UniqueIdMap GetRealIdMap(UniqueIdCollection tempIds, IDataSourceKey dataSourceKey ) {
UniqueIdMap idMap = new UniqueIdMap();
long nextLongId = GetNextId(tempIds.Count, dataSourceKey);
object nextId;
// Build a UniqueIdMap containing the mapping of temporary to real Id values.
foreach (UniqueId aUniqueId in tempIds) {
try {
nextId = Convert.ChangeType(nextLongId, aUniqueId.Property.DataType);
} catch {
throw new NotSupportedException("This id generator cannot generate ids of type " + aUniqueId.Property.DataType);
}
idMap.Add(aUniqueId, nextId);
nextLongId++;
}
return idMap;
}
#region Server-side custom Id allocation
/// <summary>
/// Perform allocation and return the starting next Id value.
/// This sample disallows Id allocation for more than MaxGroupSize (1000) values
/// at a time. It also always allocates 100 new values at a time.
/// These numbers are arbitrary, and for illustration only.
/// </summary>
private long GetNextId(int count, IDataSourceKey dataSourceKey) {
// Serialize access to GetNextId - the BOS is multi-threaded and concurrent saves can be in progress.
lock (__syncLock) {
// Do some validation before proceeding.
TraceFns.Assert(count > 0, "GetNextId requires a positive integer as its arg.");
TraceFns.Assert(count <= MaxGroupSize,"Cannot allocate more than "
+ MaxGroupSize + " in any one call to GetNextId");
// Allocate more Ids only if necessary. This allocates 100 at a time.
if (__nextId + count > __maxNextId) {
AllocateMoreIds(count, dataSourceKey);
}
long result = __nextId;
__nextId += count; // Next time we'll start here.
return result;
}
}
/// <summary>
/// Allocate more "real" Id values. This sample uses a table called NextId with
/// "Name" and "NextId" columns. It uses a "global" allocation strategy - that is,
/// Id values are not assigned on a table-specific basis, but globally within the application.
/// </summary>
private void AllocateMoreIds(int count, IDataSourceKey dataSourceKey) {
const String sqlSelect = "select NextId from NextId where Name = 'GLOBAL'";
const String sqlUpdate = "update NextId set NextId={0} where Name = 'GLOBAL' and NextId={1}";
// Allocate the larger of the two: amount requested or the default alloc group size.
count = Math.Max(count, DefaultGroupSize);
AdoHelper adoHelper = GetAdoHelper(dataSourceKey);
IDbConnection aConnection = adoHelper.CreateDbConnection(true);
aConnection.Open();
using (aConnection) {
IDbCommand selectCommand = adoHelper.CreateDbCommand(aConnection);
IDbCommand updateCommand = adoHelper.CreateDbCommand(aConnection);
for (int trys = 0 ; trys <= MaxTrys ; trys++) {
selectCommand.CommandText = sqlSelect;
IDataReader aDataReader = selectCommand.ExecuteReader();
if (!aDataReader.Read()){
throw new ApplicationException("Unable to locate 'NextId' record");
}
Object tmp = aDataReader.GetValue(0);
long nextId = (long) Convert.ChangeType(tmp, typeof(Int64));
long newNextId = nextId + count;
aDataReader.Close();
// Update the table to reflect the new NextId value to be assigned next time.
updateCommand.CommandText = String.Format(sqlUpdate, newNextId, nextId);
// If only one record was affected - we're ok; otherwise try again.
if (updateCommand.ExecuteNonQuery() == 1) {
__nextId = nextId;
__maxNextId = newNextId;
return;
}
}
}
throw new ApplicationException("Unable to generate a new id");
}
/// <summary>
/// Retrieve an AdoHelper to use in data access. This sample issues
/// select and update commands to the database, using the AdoHelper.
/// </summary>
private AdoHelper GetAdoHelper(IDataSourceKey dataSourceKey) {
// Option 1 - if you want to reference both IdeaBlade.EntityModel.Edm.v4
// and IdeaBlade.Rdb.v4 assemblies.
IdeaBlade.EntityModel.Edm.EdmKey edmKey =
dataSourceKey as IdeaBlade.EntityModel.Edm.EdmKey;
RdbKey rdbKey = edmKey.RdbKey as RdbKey;
return rdbKey.AdoHelper;
// Option 2 - you might not want to reference the IdeaBlade.EntityModel.Edm.v4 assembly on your
// client (since it in turn references Entity Framework assemblies). You could instead use
// a little reflection.
// Type t = InternalFns.GetIdeaBladeType("IdeaBlade.EntityModel.Edm.v4.EdmKey", true);
// RdbKey rdbkey = t.GetProperty("RdbKey").GetValue(dataSourceKey, null) as RdbKey;
// return rdbkey.AdoHelper;
// Option 3 - You can create separate client-side vs. server-side IdGenerator implementations.
// Contact IdeaBlade for more information.
}
#endregion
// Client-side variables.
[DataMember]
private UniqueIdCollection _tempIds = new UniqueIdCollection();
[DataMember]
private int _nextBaseId;
private const int MaxTrys = 3; // Fail after 3 unsuccessful allocation attempts.
private const int DefaultGroupSize = 100; // Allocate 100 new Ids at a time.
private const int MaxGroupSize = 1000; // Only allow 1000 Ids max in a call.
// Server-side variables.
private static object __syncLock = new object();
private static long __nextId = 0;
private static long __maxNextId = 0;
}
}
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Posted By: pucsoftware
Date Posted: 03-Feb-2010 at 8:21am
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In DevForce v5.2.4.2 on Windows 7 we found the sample class, both C# & VB versions, installed here:
C:\Users\Public\Documents\DevForce\Learning Resources\040_BusObjPersistence\AddingDeleting\Snippets\NumericIdGenerator
This may be useful if you're looking for the VB version.
-------------
puctx
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Posted By: tj62
Date Posted: 03-Jan-2011 at 7:55am
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I have searched all over the place on my computer and it is not there the LearningResources folder does not exist. Except I find it for an old 2009 installatoin at:
C:\Program Files\IdeaBlade DevForce\Learning Resources
But the current installatoin is at:
C:\Program Files\DevForce 2010
where there is no Learning Resources folder at all.
Where in heck is it?
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Posted By: davidklitzke
Date Posted: 03-Jan-2011 at 9:45am
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If you are looking at DevForce 2009, you can find the files
at a location such as:
C:\Program Files\IdeaBlade DevForce\Learning
Resources\040_BusObjPersistence\AddingDeleting\Snippets\NumericIdGenerator
If you are looking at DevForce 2010, the files are not where
you might expect them to be (i.e., in the
"030_BusObjPersistence\AddingDelecting" folder). However you can find both C# and VB versions in the "030_BusObjPersistence\_MiniDemos"
folder.
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