union() expression function in logic app returning string instead of collection

[asos-chrisnorman]

Describe the Bug with repro steps

In a Logic App Standard workflow in a foreach condition, we are using a union expression function to union a collection with itself, in order to removed duplicates and get an array of distinct elements.

The reference guide states the union function returns an "Array or Object, respectively", but we are receiving the following error:

ExpressionEvaluationFailed

The execution of template action 'For_each_scenario' failed: the result of the evaluation of 'foreach' expression '@{union(body('Select_scenario_names_from_CSV'), body('Select_scenario_names_from_CSV'))}' is of type 'String'. The result must be a valid array.

What type of Logic App Is this happening in?

Standard (Portal)

Which operating system are you using?

Windows

Did you refer to the TSG before filing this issue? https://aka.ms/lauxtsg

Yes

Workflow JSON

{
    "definition": {
        "$schema": "https://schema.management.azure.com/providers/Microsoft.Logic/schemas/2016-06-01/workflowdefinition.json#",
        "actions": {
            "Create_CSV_JSON_data": {
                "inputs": {
                    "from": "@skip(outputs('Split_Lines'), 1)",
                    "select": {
                        "@{outputs('Split_Field_Names')[0]}": "@split(item(), ',')?[0]",
                        "@{outputs('Split_Field_Names')[1]}": "@split(item(), ',')?[1]",
                        "@{outputs('Split_Field_Names')[10]}": "@split(item(), ',')?[10]",
                        "@{outputs('Split_Field_Names')[11]}": "@split(item(), ',')?[11]",
                        "@{outputs('Split_Field_Names')[12]}": "@split(item(), ',')?[12]",
                        "@{outputs('Split_Field_Names')[13]}": "@split(item(), ',')?[13]",
                        "@{outputs('Split_Field_Names')[14]}": "@split(item(), ',')?[14]",
                        "@{outputs('Split_Field_Names')[2]}": "@split(item(), ',')?[2]",
                        "@{outputs('Split_Field_Names')[3]}": "@split(item(), ',')?[3]",
                        "@{outputs('Split_Field_Names')[4]}": "@split(item(), ',')?[4]",
                        "@{outputs('Split_Field_Names')[5]}": "@split(item(), ',')?[5]",
                        "@{outputs('Split_Field_Names')[6]}": "@split(item(), ',')?[6]",
                        "@{outputs('Split_Field_Names')[7]}": "@split(item(), ',')?[7]",
                        "@{outputs('Split_Field_Names')[8]}": "@split(item(), ',')?[8]",
                        "@{outputs('Split_Field_Names')[9]}": "@split(item(), ',')?[9]"
                    }
                },
                "runAfter": {
                    "Split_Field_Names": [
                        "SUCCEEDED"
                    ]
                },
                "type": "Select"
            },
            "For_each_scenario": {
                "actions": {
                    "Check_if_ASN_required": {
                        "actions": {
                            "Append_to_Links_array_(With_ASN)": {
                                "inputs": {
                                    "name": "Links",
                                    "value": "https://edi-@{parameters('environmentCode')}.asosdevelopment.com/edi/integration-test/@{replace(toLower(body('Filter_CSV_array_for_scenario')[0]?['Brand Partner Name']),'''','')}_@{item()?['Scenario']}_@{body('Invoke_po-and-asn-incrementer-workflow')?['PoNumber']}_@{body('Invoke_po-and-asn-incrementer-workflow')?['AsnNumber']}"
                                },
                                "runAfter": {
                                    "Upload_ASN_to_storage_container_": [
                                        "SUCCEEDED"
                                    ]
                                },
                                "type": "AppendToArrayVariable"
                            },
                            "Create_ASN": {
                                "inputs": {
                                    "AdvancedShipmentCreateNotification": {
                                        "ASNInDesc": {
                                            "asn_nbr": "@body('Invoke_po-and-asn-incrementer-workflow')?['AsnNumber']",
                                            "ASNInPO": [
                                                {
                                                    "ASNInItem": [
                                                        {
                                                            "final_location": "@body('Filter_CSV_array_for_scenario')[0]?['Warehouse Storage Location (ASOS Final FC Location)']"
                                                        }
                                                    ],
                                                    "po_nbr": "@body('Invoke_po-and-asn-incrementer-workflow')?['PoNumber']"
                                                }
                                            ],
                                            "vendor_nbr": "@body('Invoke_po-detail-construction-workflow')?['skuData']?['SupplierId']"
                                        }
                                    }
                                },
                                "type": "Compose"
                            },
                            "Upload_ASN_to_storage_container_": {
                                "inputs": {
                                    "parameters": {
                                        "blobName": "@{replace(toLower(body('Filter_CSV_array_for_scenario')[0]?['Brand Partner Name']),'''','')}/asns/@{body('Filter_CSV_array_for_scenario')[0]?['Scenario']}_ASN_@{body('Invoke_po-and-asn-incrementer-workflow')?['AsnNumber']}.json",
                                        "containerName": "test-data",
                                        "content": "@outputs('Create_Asn')",
                                        "overrideIfExists": "true"
                                    },
                                    "serviceProviderConfiguration": {
                                        "connectionName": "AzureBlob",
                                        "operationId": "uploadBlob",
                                        "serviceProviderId": "/serviceProviders/AzureBlob"
                                    }
                                },
                                "runAfter": {
                                    "Create_ASN": [
                                        "SUCCEEDED"
                                    ]
                                },
                                "type": "ServiceProvider"
                            }
                        },
                        "else": {
                            "actions": {
                                "Append_to_Links_array_(Without_ASN)": {
                                    "inputs": {
                                        "name": "Links",
                                        "value": "https://edi-@{parameters('environmentCode')}.asosdevelopment.com/edi/integration-test/@{replace(toLower(body('Filter_CSV_array_for_scenario')[0]?['Brand Partner Name']),'''','')}_@{item()?['Scenario']}_@{body('Invoke_po-and-asn-incrementer-workflow')?['PoNumber']}"
                                    },
                                    "type": "AppendToArrayVariable"
                                }
                            }
                        },
                        "expression": {
                            "and": [
                                {
                                    "equals": [
                                        "@body('Filter_CSV_array_for_scenario')[0]?['ASN Required']",
                                        "Y"
                                    ]
                                }
                            ]
                        },
                        "runAfter": {
                            "Upload_purchaseorder_to_storage_container": [
                                "SUCCEEDED"
                            ]
                        },
                        "type": "If"
                    },
                    "Create_Purchase_Order": {
                        "inputs": {
                            "ApprovalDate": "@utcNow()",
                            "BuyingGroupID": "@body('Invoke_po-detail-construction-workflow')?['skuData']?['buyingGroupId']",
                            "BuyingGroupName": "@body('Invoke_po-detail-construction-workflow')?['skuData']?['buyingGroup']",
                            "CurrencyCode": "@body('Filter_CSV_array_for_scenario')[0]?['PO Currency']",
                            "ExpectedDeliveryDateFirstLocation": "@body('Filter_CSV_array_for_scenario')[0]?['Requested Delivery Date']",
                            "ExpectedHandoverDate": "@body('Filter_CSV_array_for_scenario')[0]?['Requested Delivery Date']",
                            "FreightForwarder": "@body('Filter_CSV_array_for_scenario')[0]?['Delivery Party (ASOS Carrier)']",
                            "HandoverWindowEndDate": "@body('Filter_CSV_array_for_scenario')[0]?['Latest Delivery Date']",
                            "HandoverWindowStartDate": "@body('Filter_CSV_array_for_scenario')[0]?['Earliest Delivery Date']",
                            "LastUpdateDateTime": "@utcNow()",
                            "OrderNo": "@body('Invoke_po-and-asn-incrementer-workflow')?['PoNumber']",
                            "PODtl": "@body('Invoke_po-detail-construction-workflow')?['purchaseOrderDetails']",
                            "SupplierConfirmation": "Y",
                            "SupplierID": "@body('Invoke_po-detail-construction-workflow')?['skuData']?['SupplierId']",
                            "SupplierName": "@body('Invoke_po-detail-construction-workflow')?['skuData']?['SupplierName']"
                        },
                        "runAfter": {
                            "Invoke_po-and-asn-incrementer-workflow": [
                                "SUCCEEDED"
                            ]
                        },
                        "type": "Compose"
                    },
                    "Filter_CSV_array_for_scenario": {
                        "inputs": {
                            "from": "@body('Create_CSV_JSON_data')",
                            "where": "@equals(item()?['Scenario'],items('For_each_scenario')?['Scenario'])"
                        },
                        "type": "Query"
                    },
                    "Invoke_po-and-asn-incrementer-workflow": {
                        "inputs": {
                            "host": {
                                "workflow": {
                                    "id": "po-and-asn-incrementer-workflow"
                                }
                            }
                        },
                        "runAfter": {
                            "Invoke_po-detail-construction-workflow": [
                                "SUCCEEDED"
                            ]
                        },
                        "type": "Workflow"
                    },
                    "Invoke_po-detail-construction-workflow": {
                        "inputs": {
                            "body": "@body('Filter_CSV_array_for_scenario')",
                            "headers": {
                                "brandPartnerName": "@{replace(toLower(body('Filter_CSV_array_for_scenario')[0]?['Brand Partner Name']),'''','')}"
                            },
                            "host": {
                                "workflow": {
                                    "id": "po-detail-construction-workflow"
                                }
                            }
                        },
                        "runAfter": {
                            "Filter_CSV_array_for_scenario": [
                                "SUCCEEDED"
                            ]
                        },
                        "type": "Workflow"
                    },
                    "Upload_purchaseorder_to_storage_container": {
                        "inputs": {
                            "parameters": {
                                "blobName": "@{replace(toLower(body('Filter_CSV_array_for_scenario')[0]?['Brand Partner Name']),'''','')}/purchase-orders/@{body('Filter_CSV_array_for_scenario')[0]?['Scenario']}_PO_@{outputs('Create_Purchase_Order')?['OrderNo']}.json",
                                "containerName": "test-data",
                                "content": "@outputs('Create_Purchase_Order')",
                                "overrideIfExists": "true"
                            },
                            "serviceProviderConfiguration": {
                                "connectionName": "AzureBlob",
                                "operationId": "uploadBlob",
                                "serviceProviderId": "/serviceProviders/AzureBlob"
                            }
                        },
                        "runAfter": {
                            "Create_Purchase_Order": [
                                "SUCCEEDED"
                            ]
                        },
                        "type": "ServiceProvider"
                    }
                },
                "foreach": "@{union(body('Select_scenario_names_from_CSV'), body('Select_scenario_names_from_CSV'))}",
                "runAfter": {
                    "Initialise_Links_array_variable": [
                        "SUCCEEDED"
                    ]
                },
                "runtimeConfiguration": {
                    "concurrency": {
                        "repetitions": 1
                    }
                },
                "type": "Foreach"
            },
            "Select_scenario_names_from_CSV": {
                "inputs": {
                    "from": "@body('Create_CSV_JSON_data')",
                    "select": {
                        "Scenario": "@item()?['Scenario']"
                    }
                },
                "runAfter": {
                    "Create_CSV_JSON_data": [
                        "SUCCEEDED"
                    ]
                },
                "type": "Select"
            },
            "Initialise_Links_array_variable": {
                "inputs": {
                    "variables": [
                        {
                            "name": "Links",
                            "type": "array"
                        }
                    ]
                },
                "runAfter": {
                    "Select_scenario_names_from_CSV": [
                        "SUCCEEDED"
                    ]
                },
                "type": "InitializeVariable"
            },
            "Response": {
                "inputs": {
                    "body": "@variables('Links')",
                    "statusCode": 200
                },
                "kind": "Http",
                "runAfter": {
                    "For_each_scenario": [
                        "SUCCEEDED"
                    ]
                },
                "type": "Response"
            },
            "Split_Field_Names": {
                "inputs": "@split(first(outputs('Split_Lines')), ',')",
                "runAfter": {
                    "Split_Lines": [
                        "SUCCEEDED"
                    ]
                },
                "type": "Compose"
            },
            "Split_Lines": {
                "inputs": "@split(triggerBody(),decodeUriComponent('%0D%0A'))",
                "runAfter": {},
                "type": "Compose"
            }
        },
        "contentVersion": "1.0.0.0",
        "outputs": {},
        "triggers": {
            "When_a_HTTP_request_is_received": {
                "kind": "Http",
                "type": "Request"
            }
        }
    },
    "kind": "Stateful"
}

Screenshots or Videos

Browser

Edge

Additional context

No response