Creating relationships in Power BI is as simple as it can get but to be able to edit/create relationships in Power BI with TE is something that requires enabling one feature.
To begin with open a Power BI file and then connect Tabular Editor to it and then navigate to Tools > Preferences > Features > Check allow unsupported modelling operations
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Now right click on Relationships option in TOM Explorer and choose Create > Relationship
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Next a dialog box will open in which you need to specify the From and To side, make sure you fill the options correctly, the first time I tried I filled Customer in From and Sales in To
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Then just click OK, save the model and go back to Power BI, and you can see relationship has been created for us.
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Now if you want to edit any existing relationship, just right click and choose the Edit Relationship option.
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make sure you fill the options correctly, the first time I tried I filled Customer in From and Sales in To - Please explain this I have got an error. Why I received and JSON error