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static exist Method Design Pattern

  • 项目

Applies To: Microsoft Dynamics AX 2012 R3, Microsoft Dynamics AX 2012 R2, Microsoft Dynamics AX 2012 Feature Pack, Microsoft Dynamics AX 2012

Each table with a key should have a static exist method. Use it to check if a record that fulfills the specified key actually exists.

The exist method must:

  • Be static because it is used to check if any table object (record) exists among all the objects of the table class.

  • Return a boolean value.

  • Take an argument of the type of the key of the table or a list of arguments if the key consists of more than one field. If there is a list of arguments, they must be in the same order as the fields in the index that are used for the table's key.

  • Check for the most effective, existing index in the record against the supplied key, and then return true if it is in the table. If not, false.

  • Run on both the client and server. This is the default behavior. You can also make it explicit by putting "client server" in the declaration, but do not specify a single tier in the declaration (either the client or the server).

The method must be used whenever one record should be checked that is exists based on its key.

Example

The following code is an example of the static exist method design pattern.

static boolean exist(CustGroupId custGroupId)
{
    return custGroupId 
        && (select firstOnly RecId from custGroup
            index hint GroupIdx
            where custGroup.custGroup == custGroupId).RecId != 0;
}

See also

Microsoft Dynamics AX Design Patterns

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