How To Fix /IWBEP/CM_V4_MED357 - Complex type '&1' must not contain complex collection

SAP Error Message - Details

• Message type: E = Error

• Message class: /IWBEP/CM_V4_MED -

• Message number: 357

• Message text: Complex type '&1' must not contain complex collection

Self-Explanatory Message

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Smart SAP Assistant

• What is the cause and solution for SAP error message /IWBEP/CM_V4_MED357 - Complex type '&1' must not contain complex collection ?

  The SAP error message /IWBEP/CM_V4_MED357 indicates that there is an issue with the structure of a complex type in your OData service. Specifically, it states that the complex type &1 must not contain a complex collection. This error typically arises when you are trying to define a complex type that includes a collection of other complex types, which is not allowed in certain contexts within OData services.
  Cause:
  
  Complex Type Definition: In OData, a complex type can contain properties, but it cannot contain a collection of complex types. If you have defined a property in your complex type as a collection of another complex type, this will trigger the error.
  Service Metadata: The service metadata might be incorrectly defined, leading to this error when the service is being consumed or tested.
  
  Solution:
  
  
  Review Complex Type Definition: Check the definition of the complex type that is causing the error. Ensure that it does not include any properties that are defined as collections of complex types. If you need to represent a collection, consider using an entity type instead of a complex type.
  Example:
  
  Instead of defining a complex type like this:
  define type ZMyComplexType {
      property1 : String;
      property2 : Collection of ZAnotherComplexType;  // This will cause the error
  }
  
  You should define it like this:
  define type ZMyComplexType {
      property1 : String;
      property2 : ZAnotherEntityType;  // Use an entity type instead
  }
  
  
  
  
  Use Entity Types for Collections: If you need to represent a collection of complex types, consider defining an entity type for the collection and then referencing that entity type in your complex type.
  
  
  Regenerate Service: After making changes to the data model, regenerate the OData service and check if the error persists.
  
  
  Check Service Implementation: If you are implementing the service, ensure that the logic does not attempt to return a collection of complex types in the response.
  
  
  Related Information:
  
  OData Specification: Familiarize yourself with the OData V4 specification, which outlines the rules for defining complex types and entity types.
  SAP Gateway: If you are using SAP Gateway, refer to the documentation for guidelines on defining data models and OData services.
  Debugging: Use transaction codes like /IWFND/ERROR_LOG to check for additional error messages that might provide more context on the issue.
  
  By following these steps, you should be able to resolve the error and correctly define your OData service's data model.