Dynamic mapping adf copy activity

Question

Dynamic mapping adf copy activity

Krishnamohan Nadimpalli 406

Hi

I am trying to do a dynamic mapping between file to SQL Table in ADF Copy activity. In the mapping section, I am adding the following dynamic content , for just one column for testing purpose. But it gives error "Expression of type: 'String' does not match the field: 'mappingV2'. Expected type is 'Object'." Please let me know if there is any solution for this User's image

{
                        "type": "TabularTranslator",
                        "mappings": [
                            {
                                "source": {
                                    "name": "WERKS",
                                    "type": "String",
                                    "physicalType": "String"
                                },
                                "sink": {
                                    "name": "Plant Key",
                                    "physicalType": "String"
                                }
                            }
						]
                    }

phemanth 15,755 Reputation points Microsoft External Staff Moderator

2024-06-10T13:10:20.53+00:00
@Krishnamohan Nadimpalli

Thanks for using MS Q&A platform and posting your query

The error message "Expression of type: 'String' does not match the field: 'mappingV2'. Expected type is 'Object'" in Azure Data Factory (ADF) Copy activity indicates a mismatch between the data type you're providing and the data type expected by the target field.

In your case, it seems you're trying to map a single string value to a field that expects an object.

Here are ways to fix this issue:

Convert the string value to an object: If you want to set multiple properties within the target field, you can use the @json() function to convert your string value into a JSON object. For instance, if your string value contains key-value pairs separated by commas, you can use:

@json('{"key1":"value1", "key2":"value2"}')

Modify the target field to accept a string: If you only need to set a single value as a string, you might need to modify the target field's definition to accept a string type. This would depend on the specific configuration of your ADF pipeline.

Check for typos: Ensure there are no typos in the field name "mappingV2". The error message might be referring to a different field than intended.

For more information on dynamic content in ADF Copy Activity mappings, you can refer to the Microsoft Documentation on [Azure Data Factory dynamic content mapping]https://blogs.perficient.com/2022/07/21/column-mappings-as-a-dynamic-content-in-azure-data-factory/

Hope this helps. Do let us know if you any further queries.
Krishnamohan Nadimpalli 406 Reputation points

2024-06-11T04:31:56.1233333+00:00

If I provide the following in the column mapping, I am able to map. But when I put the same in parameters , it does not take

@json('

{

"type": "TabularTranslator","mappings":

[

{"source": {"name": "period_id","type": "String"},"sink": {"name": "TAG","type": "String"}},

{"source": {"name": "period_ending_datetime","type": "String"},"sink": {"name": "SHORT","type": "String"}}

]

}

')
phemanth 15,755 Reputation points Microsoft External Staff Moderator

2024-06-12T05:59:32.34+00:00

@Krishnamohan Nadimpalli We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.

1 answer

Your answer

phemanth 15,755 Reputation points Microsoft External Staff Moderator

2024-06-10T13:10:20.53+00:00

@Krishnamohan Nadimpalli

Thanks for using MS Q&A platform and posting your query

The error message "Expression of type: 'String' does not match the field: 'mappingV2'. Expected type is 'Object'" in Azure Data Factory (ADF) Copy activity indicates a mismatch between the data type you're providing and the data type expected by the target field.

In your case, it seems you're trying to map a single string value to a field that expects an object.

Here are ways to fix this issue:

Convert the string value to an object: If you want to set multiple properties within the target field, you can use the @json() function to convert your string value into a JSON object. For instance, if your string value contains key-value pairs separated by commas, you can use:

@json('{"key1":"value1", "key2":"value2"}')

Modify the target field to accept a string: If you only need to set a single value as a string, you might need to modify the target field's definition to accept a string type. This would depend on the specific configuration of your ADF pipeline.

Check for typos: Ensure there are no typos in the field name "mappingV2". The error message might be referring to a different field than intended.

For more information on dynamic content in ADF Copy Activity mappings, you can refer to the Microsoft Documentation on [Azure Data Factory dynamic content mapping]https://blogs.perficient.com/2022/07/21/column-mappings-as-a-dynamic-content-in-azure-data-factory/

Hope this helps. Do let us know if you any further queries.
Krishnamohan Nadimpalli 406 Reputation points

2024-06-11T04:31:56.1233333+00:00

If I provide the following in the column mapping, I am able to map. But when I put the same in parameters , it does not take

@json('

{

"type": "TabularTranslator","mappings":

[

{"source": {"name": "period_id","type": "String"},"sink": {"name": "TAG","type": "String"}},

{"source": {"name": "period_ending_datetime","type": "String"},"sink": {"name": "SHORT","type": "String"}}

]

}

')
phemanth 15,755 Reputation points Microsoft External Staff Moderator

2024-06-12T05:59:32.34+00:00

@Krishnamohan Nadimpalli We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.

Answer 1

@Krishnamohan Nadimpalli

The image you sent confirms that you're able to successfully define the mapping within the column mapping section of your Azure Data Factory (ADF) Copy Activity, but encountering an error when using the same value in a parameter.

Here's why this might be happening and how to address it:

ADF Parameter Types:

ADF parameters are designed to hold specific data types like strings, integers, or booleans. They cannot inherently store complex objects like the mapping definition you're using.

Possible Solutions:

Pass Mapping as a String:

While not ideal, you can try storing the entire mapping definition as a string within a parameter. However, this approach makes it difficult to maintain and edit the mapping later. Create a Separate JSON File:

Consider creating a separate JSON file containing the mapping definition. Then, within your ADF pipeline, use the @pipeline().parameters.PathToYourJSONFile expression to reference the file's location. This approach keeps your mapping definition separate and easier to manage.

Use a More Suitable Data Structure (Advanced):

If your scenario involves more complex data manipulation, explore using ADF variables. Variables allow storing and referencing complex data structures during pipeline execution. This solution might require a deeper understanding of ADF variables and their usage.

Recommendation:

For readability and maintainability, creating a separate JSON file for the mapping definition (solution 2) is generally the recommended approach. This keeps your pipeline code clean and separates configuration details.

Additional Tips:

Ensure the JSON file containing the mapping definition is accessible by your ADF pipeline during execution.
Double-check the path used in the @pipeline().parameters.PathToYourJSONFile expression to ensure it points to the correct location of your JSON file

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Dynamic mapping adf copy activity

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