Data Source

[jaw19883]

Very new to Power Bi, but not Excel. My question resolves around a changing data source. As a background, I am in K-12 education, so think of a gradebook and units in a course. My data source is an exported CSV/Excel file (which is horrible), but at this point no choice in that matter. 

So, lets say my entire course has 3 units of instruction and each unit has 3 assignments, so my exported gradebook woul look like the following:

Exported Gradebook fields

Student
Student ID

Section

Unit 1 Assignment 1

Unit 1 Assignment 2

Unit 1 Assignment 3

Unit 2 Assignment 1

Unit 2 Assignment 2

Unit 2 Assignment 3

Unit 3 Assignment 1

Unit 3 Assignment 2

Unit 3 Assignment 3

Here is where I am running into an issue. My initial data source (file.xlsx) has no records (beginning of the semester). This is where I have to go in and set up my data model, measures, dashboards, etc. Lets say after the first unit, I want to pull that data into my Power Bi dashboard to report on the first unit. Now my exported gradebook has Student,Student Id, section, unit 1 assignment 1, unit 1 assignment 2, unit 1 assignment 3. So I export gradebook and save it as the original file name (file.xlsx) in the same location and refresh. I get a refresh error that says (the key didn't match any rows in the table. 

I have dozens of courses that I have to do this for, so I need to setup an inital datasource and data model and then replace that data source with an updated version that includes actual unit data. Essentially the original has the data model with filed names, tables, etc. just no records. then I come in periodically and drop in the same files (filed names, etc.) but with actual data in it at several intravels through out the semester. 

[amitchandak]

@jaw19883 ,Can you share sample data and sample output in table format? Or a sample pbix after removing sensitive data.

[jaw19883 · Accepted solution]

I think I got it at least partially figured out. What I was doing was saving the newer version of the data source over/replace the existing one from the folder where the source was saved and then refreshing data, and thus generating the error. 

What I did was inside Power Bi in transforming the data, I changed the source and that has worked thus far...Thank you for the quick response. I am going to continue progressing with my testing to see how far I can go with it and will circle back here if I run into something down the line.