PredicateDescription and Composite
Printed From: IdeaBlade
Category: DevForce
Forum Name: DevForce 2012
Forum Discription: For .NET 4.5
URL: http://www.ideablade.com/forum/forum_posts.asp?TID=4655
Printed Date: 26-Apr-2025 at 4:11pm
Topic: PredicateDescription and Composite
Posted By: BillG
Subject: PredicateDescription and Composite
Date Posted: 06-Mar-2014 at 7:01am
I have a form with 6 fields on it which are search criteria fields. They are SSN, EmployeeNo, CarcNo, LastName, FirstName, Status and office. When the user clicks Find, I check to see which ones are filled in and I build a MemberQO query object. I then pass the MemberQO to my Repository method GetMembers() where I do the following.
public IEnumerable<MembersList> GetMembers(MemberQO memberQO)
{
CompositePredicateDescription cpd;
PredicateDescription p1, p2, p3, p4, p5, p6 = null;
if (memberQO.SocSecNo != string.Empty)
{
p1 = PredicateBuilder.Make(typeof (Member), "SocSecNo", FilterOperator.IsEqualTo, memberQO.SocSecNo);
}
if (memberQO.CardNo != string.Empty)
{
p2 = PredicateBuilder.Make(typeof (Member), "CardNo", FilterOperator.IsEqualTo,
memberQO.CardNo);
}
if (memberQO.EmployeeNo != string.Empty)
{
p3 = PredicateBuilder.Make(typeof(Member), "EmployeeNumber", FilterOperator.IsEqualTo,
memberQO.EmployeeNo);
}
if (memberQO.LastName != string.Empty)
{
p3 = PredicateBuilder.Make(typeof (Member), "LastName", FilterOperator.IsEqualTo,
memberQO.LastName);
}
if (memberQO.FirstName != string.Empty)
{
p4 = PredicateBuilder.Make(typeof(Member), "FirstName", FilterOperator.IsEqualTo,
memberQO.FirstName);
}
if (memberQO.Office != string.Empty)
{
p5 = PredicateBuilder.Make(typeof(Member), "Office", FilterOperator.IsEqualTo,
memberQO.Office);
}
if (memberQO.Status != string.Empty)
{
p6 = PredicateBuilder.Make(typeof(Member), "Status", FilterOperator.IsEqualTo,
memberQO.Status);
}
var query = Manager.MembersLists
.OrderBy(m => m.SocSecNo);
var results = query.Execute();
return results;
}
Now what is the best way to combine those into a CompositePredicateDescription, None, some, or all of the search fields could be used.
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Replies:
Posted By: BillG
Date Posted: 07-Mar-2014 at 12:41pm
Posted By: DenisK
Date Posted: 07-Mar-2014 at 6:48pm
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Hi Bill,
This should take you in the right directions.
http://drc.ideablade.com/devforce-2012/bin/view/Documentation/predicatebuilder-methods
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Posted By: DenisK
Date Posted: 11-Mar-2014 at 9:36am
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Hi Bill,
This page that shows how to create a completely dynamic DevForce queries might also interest you.
http://drc.ideablade.com/devforce-2012/bin/view/Documentation/dynamic-queries - http://drc.ideablade.com/devforce-2012/bin/view/Documentation/dynamic-queries
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Posted By: BillG
Date Posted: 12-Mar-2014 at 12:02pm
thanks to Jay from IdeaBlade, I have a solution to my problem which i wish to share in case others come across this same situation.
This code allows me to pass a Query Object to my Repository GetMembers() method and then build a predicateDescription for each property of the QueryObject that is not null. i then pass the PredicateDescription objects to the CombinePreds as an arrary and the CombinePreds picks out the non nulls ones and combines them. It then passes the combined one back to my Get method which then is used in the .Where clause of the query.
Thans again to Jay for your help. As I have always said IdeaBlade has a great support team for the customers.
public IPredicateDescription CombinePreds(params PredicateDescription[] preds)
{
var nonNullPreds = preds.Where(pd => pd != null).ToArray();
var result = PredicateBuilder.And(nonNullPreds);
return result;
}
public IEnumerable<MembersList> GetMembers(MemberQO memberQO)
{
IPredicateDescription compositePred;
PredicateDescription p1 = null, p2 = null, p3 = null, p4 = null, p5 = null, p6 = null;
if (memberQO.SocSecNo != null)
{
p1 = PredicateBuilder.Make(typeof (MembersList), "SocSecNo", FilterOperator.IsEqualTo, memberQO.SocSecNo);
}
if (memberQO.CardNo != null)
{
p2 = PredicateBuilder.Make(typeof (MembersList), "CardNo", FilterOperator.IsEqualTo,
memberQO.CardNo);
}
if (memberQO.EmployeeNo != null)
{
p3 = PredicateBuilder.Make(typeof(MembersList), "EmployeeNumber", FilterOperator.IsEqualTo,
memberQO.EmployeeNo);
}
if (memberQO.LastName != null)
{
p3 = PredicateBuilder.Make(typeof (MembersList), "LastName", FilterOperator.StartsWith,
memberQO.LastName);
}
if (memberQO.FirstName != null)
{
p4 = PredicateBuilder.Make(typeof(MembersList), "FirstName", FilterOperator.StartsWith,
memberQO.FirstName);
}
if (memberQO.Office != null)
{
p5 = PredicateBuilder.Make(typeof(MembersList), "Office", FilterOperator.IsEqualTo,
memberQO.Office);
}
if (memberQO.Status != null)
{
p6 = PredicateBuilder.Make(typeof(MembersList), "Status", FilterOperator.IsEqualTo,
memberQO.Status);
}
compositePred = CombinePreds(p1, p2, p3, p4, p5, p6);
var query = Manager.MembersLists
.Where(compositePred)
.OrderBy(m => m.SocSecNo);
var results = query.Execute();
return results;
}
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