Chapter 10: Importing an Old Map

Bringing an existing mapping spreadsheet into Bridger for the first time.

Not every engagement starts from scratch. If a project was mapped in Excel before Bridger was in the picture — or carried over from a previous engagement — you don't have to re-enter that work by hand. Bridger can read an existing mapping spreadsheet and reconstruct the project from it, provided you give it a template that describes how the spreadsheet is laid out.

How It Works

The import process is template-driven. Bridger doesn't try to guess what your spreadsheet's columns mean — you tell it, by creating a report template whose column definitions match your spreadsheet's headers. Each template column maps a spreadsheet header to a Bridger source path, which tells the importer where to write that value in the data model.

Once the template exists, the import itself is straightforward: pick the file, pick the template, review the analysis, and confirm. Bridger does the rest.

Step 1: Read the Spreadsheet

Before building the template, open the spreadsheet and take stock of what's there. You're looking for sheets that contain usable mapping data — typically a sheet per source or target table, or a single sheet listing all column mappings. Note the column headers on those sheets. Those headers are what you'll be matching against in the template.

Not every sheet needs to be imported, and not every column needs a corresponding source path. The template only needs to cover the data you actually want to bring in.

Step 2: Build the Import Template

Create a new report template in Bridger. For each sheet in the spreadsheet you want to import, add a corresponding sheet definition to the template. Set the sheet name to match exactly, set the iterator type to match what kind of data the sheet contains (columns, mappings, and so on), and add column definitions whose names match the spreadsheet headers. The report template editor is covered in Appendix A.

The right side of each column definition is the source path — the Bridger property that this column's data should be written to on import. Appendix B lists all available source paths. For a mapping sheet, for example, you might map a "TransLogic" header to mapping.notation.TransLogic, a "Status" header to mapping.status.name, and so on.

Step 3: Import from Excel

From the menu bar, choose File → Import → Import from Excel…. The import dialog opens.

Select the spreadsheet file using the Browse button. Then select the template you created from the template dropdown. Bridger immediately analyzes the file against the template — it reads each sheet, matches it to a template sheet definition, and reports what it found. The sheet list shows which sheets matched and how many data rows each contains. A summary at the top shows the total processable sheet and row counts.

If any issues are detected during analysis — unrecognized sheet names, headers that don't match the template, or sheets that can't be processed — they appear in the messages panel below the sheet list. Warnings don't block the import; fatal errors do.

If your spreadsheet doesn't include database or schema names for the tables, expand Advanced Import Settings and fill in the source and target database and schema defaults. Any table or mapping that has no database or schema value in the spreadsheet will have these defaults applied. Values already present in the spreadsheet are not overwritten.

Deselect any sheets you don't want to process, then click Import. Bridger creates a new project from the spreadsheet data and adds it to the current workbook.

After the Import

Run a workbook validation pass (Tools → Validate Workbook…) once the import completes. The validator will surface any orphaned references or missing fields that the import couldn't resolve, giving you a clean list of items to clean up before working with the project further. The validation workflow is covered in Chapter 5.

Expect Some Iteration

Depending on how the original spreadsheet was maintained, getting a clean import may take more than one pass. Spreadsheets don't enforce structure, and analysts working without a tool like Bridger tend to improvise — a column labeled "Source Table" might contain table names in some rows and fully qualified table.column references in others, or status values might be inconsistent across sheets. The importer will bring in what it can and flag what it can't resolve, but it can't fix source data that doesn't match what the template expects.

The practical approach is to treat the first import as a diagnostic. Run it, review the validation output and message log, then go back to the spreadsheet and clean up the problem rows. Repeat until the import comes in cleanly. It can be tedious work, but it only has to be done once — and the result is a project that lives inside Bridger's enforced structure, where consistency is guaranteed going forward.

What's Next

Chapter 11: Leveraging AI Assistance covers Bridger's optional Ollama integration, which can accelerate the mapping work once your project is in place.