Collection classes in AX – What, When and How to use
Data inserting, traversing and retrieving can be done with many different ways in AX. We do have different collection classes for it and each one has its own importance and performance impact. Let’s talk about each one by one and compare it. List – are structures, contain values of any X++ type that are accessed sequentially – all values must be of same X++ type (specified through baseEnum types) – type is defined on creation and cannot be modified after initialization – can be traversed through ListEnumerator class – values can be added from both sides e.g. using addEnd() and addStart() methods Example 1 static void ListExample1(Args _args) { List list = new List(Types::String); // Declare and initialize List of String type ListEnumerator enumerator; // Declare ListEnumerator class to traverse list list.addEnd(“Faisal”); // Add values at End of the List list.addEnd(“Fareed”); // Add values at End of the List list.addStart(“AX Developer”); // Add values at Start of the List enumerator = list.getEnumerator(); // initialize listEnumerator class object while (enumerator.moveNext()) { print enumerator.current(); } pause; } Output: Traverse from left to right Example 2 Lists can be initialized from container too. static void ListExample2(Args _args) { Container companyRange; // Declare container List list; // Declare List ListEnumerator enumerator; // Declare ListEnumerator class to traverse list companyRange = [curext()]; // initialize container with current company // we can pass multiple values here but need to be of same datatype as this is used in List in below code list = con2List(companyRange); enumerator = list.getEnumerator(); // initialize listEnumerator class object while (enumerator.moveNext()) { print enumerator.current(); } pause; } Example 3 Below code is actually an example to copy user roles from one user to another. Where I used ‘List’ to store records what roles have been moved across. static void ListExample3(Args _args) { boolean ret = true; SecurityRole securityRole; SecurityUserRole securityUserRole; SecurityUserRole securityUserRoleExist; SecurityUserRole securityUserRoleInsert; OMUserRoleOrganization userRoleOrganization, userRoleOrganization_Insert; List copiedUserRoles = new List(Types::String); ListEnumerator lEnumerator; try { while select securityUserRole where securityUserRole.User == fromUser notExists join * from securityUserRoleExist where securityUserRoleExist.SecurityRole == securityUserRole.SecurityRole && securityUserRoleExist.User == toUser { select securityRole where securityRole.RecId == securityUserRole.SecurityRole; copiedUserRoles.addStart(securityRole.Name); securityUserRoleInsert.initValue(); securityUserRoleInsert.SecurityRole = securityUserRole.SecurityRole; securityUserRoleInsert.User = toUser; securityUserRoleInsert.insert(); securityUserRoleInsert.clear(); while select userRoleOrganization where userRoleOrganization.User == fromUser && userRoleOrganization.SecurityRole == securityUserRole.SecurityRole { userRoleOrganization_Insert.initValue(); userRoleOrganization_Insert.OMHierarchyType = userRoleOrganization.OMHierarchyType; userRoleOrganization_Insert.OMInternalOrganization = userRoleOrganization.OMInternalOrganization; userRoleOrganization_Insert.SecurityRole = userRoleOrganization.SecurityRole; userRoleOrganization_Insert.SecurityRoleAssignmentRule = userRoleOrganization.SecurityRoleAssignmentRule; userRoleOrganization_Insert.User = toUser; userRoleOrganization_Insert.insert(); userRoleOrganization_Insert.clear(); } } } catch { ret = false; } if (ret) { lEnumerator = copiedUserRoles.getEnumerator(); if (copiedUserRoles.empty()) info(strFmt(“User %1 and %2 already have the same user role”,fromUser, toUser)); while (lEnumerator.moveNext()) { info(strFmt(‘%1’,lEnumerator.current())); } } else error(strFmt(“Aborted please review error list above”)); } You can also have a look on this post to find difference between Iterators and Enumerators. Maps – can be used as a temp data store for the given scope of a process – are much quicker than temp tables – allows you to associate one value (the key) with another value – values can be any valid X++ type static void mapExample1(Args _args) { Map mapExample; MapEnumerator mapEnumeratorExample; CustTable custTable; mapExample = new Map(Types::String,Types::String); select custTable where custTable.AccountNum == “144212”; mapExample.insert(CustTable.AccountNum, CustTable.name()); mapEnumeratorExample = new MapEnumerator(mapExample); while (mapEnumeratorExample.moveNext()) { if (!mapExample.empty()) { print mapExample.lookup(custTable.AccountNum); } } pause; } Good information about Maps is also shared here Containers MSDN page describes it very best http://msdn.microsoft.com/en-us/library/aa874816.aspx Containers can be used to get multiple values returned from any method. Original method private container getActualAmount() { Container amountContainer; container textContainer; ; for() { amountContainer = conIns(amountContainer); textContainer = conIns(textContainer); } return [amountContainer, textContainer]; } Called From container AmountsC = conNull(); container TextC = conNull(); [AmountsC, TextC] = this.getActualAmount(); Set values to use for your logic ExampleTable.Field1 = conPeek(AmountsC,1); ExampleTable.Field2 = conPeek(AmountsC,2); Important points about Containers They are value based structure. So no class based object stored on it. They are similar to linked list or array like structured. Their size fixed at time of declaration. When you insert update or delete any value from container, a new container is created. They always copied by value. Containers are base 1 not like array based zero.