Question

 How can I transform nested JSON data into a structured table format?
I have a JSON file containing deeply nested objects and arrays, and I want to load this data into Power BI in a structured table format. The goal is to extract relevant fields, flatten the hierarchy, and convert the data into a relational structure suitable for analysis. What is the best approach using Power Query functions like Record.ToTable, Table.ExpandRecordColumn, or Table.ExpandListColumn to ensure a clean transformation?

Answer 1

Use Power BI Power Query transformation to change the input structure stepwise from the original nested JSON structure to the structured table arrangement. After loading the JSON file into Power BI using the Power Query Editor, the essential steps include expanding records and lists iteratively till the nested structure is reduced to a normal table.

Begin with Record.ToTable if the top-level JSON structure is a record (dictionary) or apply Table.ExpandRecordColumn to flatten nested objects directly. For any arrays inside the JSON, apply Table.ExpandListColumn to convert them into rows. Then, alternate the expansion of records and lists as per the structure of your JSON. Through the drilling down process, rename and reorder columns for clarity.

Now go ahead and remove unneeded columns, filter out nulls, and set data types to finalize the tidy Table. If the structures in the JSON vary significantly or fields are optional, try...otherwise, they can be used to handle errors gracefully. The stepwise transformation enables Power BI to treat what was originally nested data as a well-structured relational dataset for reporting.