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A Energy Question Customized Operate to Rename all Columns at As soon as in a Desk


A Power Query Custom Function to Rename all Columns at Once in a Table

I’m concerned with a Energy BI growth up to now few days. I bought some knowledge exported from numerous methods in numerous codecs, together with Excel, CSV and OData. The CSV recordsdata are knowledge export dumps from an ERP system. Working with ERP methods might be very time consuming, particularly once you don’t have entry to the info mannequin, and also you get the info in uncooked format in CSV recordsdata. It’s difficult, as within the ERP methods, the desk names and column names aren’t consumer pleasant in any respect, which is smart. The ERP methods are being utilized in numerous environments for a lot of totally different prospects with totally different necessities. So if we are able to get our palms to the underlying knowledge mannequin, we see configuration tables retaining column names. Among the columns are customized constructed to cowl particular wants. The tables could have many columns that aren’t essentially helpful for analytical functions. So it’s fairly essential to have a very good understanding of the underlying entity mannequin. Anyhow, I don’t wish to go off-topic.

The Drawback

So, right here is my state of affairs. I obtained about 10 recordsdata, together with 15 tables. Some tables are fairly small, so I didn’t trouble. However a few of them are actually extensive like having between 150 to 208 columns. Good!

Wanting on the column names, they can’t be tougher to learn than they’re, and I’ve a number of tables like that. So I’ve to rename these columns to one thing extra readable, extra on this facet of the story later.

Background

I emailed again to my buyer, asking for his or her assist. Fortunately they’ve a really good knowledge skilled who additionally understands their ERP system in addition to the underlying entity mannequin. I emailed him all the present column names and requested if he can present extra user-friendly names. He replied me again with a mapping desk in Excel. Right here is an instance to indicate the Column Names Mapping desk:

Column Names Mapping

I used to be fairly proud of the mapping desk. Now, the following step is to rename all columns is predicated on the mapping desk. Ouch! I’ve virtually 800 columns to rename. That’s actually a ache within the neck, and it doesn’t sound fairly proper to burn the challenge time to rename 800 columns.

However wait, what about writing automating the rename course of? Like writing a customized operate to rename all columns directly? I recall I learn a superb weblog publish about renaming a number of columns in Energy Question that Gilbert Quevauvilliers wrote in 2018. I undoubtedly suggest taking a look at his weblog publish. So I have to do one thing much like what Gilbert did; making a customized operate that will get the unique columns names and brings again the brand new names. Then I exploit the customized operate in every desk to rename the columns. Simple!

The Resolution

Earlier than we begin, I must have my mapping desk in Energy BI. So I create a brand new desk utilizing the Enter Knowledge performance. Then I copy the info from my mapping desk and paste it into the brand new desk. I identify the brand new desk Column Names Mapping. The principle purpose to make use of the Enter Knowledge performance as a substitute of getting knowledge instantly from the file (in my case an Excel file) is that if for any purpose sooner or later we miss the mapping file, the operate under can’t discover the columns to map. Therefore, it brings again the unique column names. This implies if we created an information mannequin on high of the brand new column names, then the entire mannequin breaks, which is not any good. I additionally disable load on the Column Names Mapping question as I don’t must have it in my knowledge mannequin.

Creating fnRenameColumnsFromRefQuery Customized Operate

The operate reads via the Column Names Mapping desk and renames the columns of the question that we invoked the operate in when it finds the matching. If it doesn’t discover the matching, it leaves the column identify is. Right here you go, that is the operate I got here up with.

//fnRenameColumnsFromRefQuery
(ColumnName as textual content) as textual content =>
let
    Supply = 
        if (
            Record.Incorporates(
                Report.FieldNames(#sections[Section1]), 
                "Column Names Mapping"
                ) 
             ) = true 
        then #"Column Names Mapping" 
        else null,
    ColumnNewName = 
        attempt 
            if Record.Incorporates(Supply[Column Name], ColumnName) = true 
            then 
                if Textual content.Trim(Desk.SelectRows(Supply, every ([Column Name] = ColumnName)){0}[Description]) = "" 
                then ColumnName 
                else Desk.SelectRows(Supply, every ([Column Name] = ColumnName)){0}[Description] 
            else Supply 
        in any other case ColumnName
in
    ColumnNewName

You possibly can obtain the previous expressions from right here.

Right here is the way it works:

  • The fnRenameColumnsFromRefQuery accepts a ColumnName parameter as textual content and the output of the operate is a textual content.
  • The Supply step checks the existence of a Column Names Mapping question. The Column Names Mapping is the mapping tables proven within the previous picture that holds the unique column names and their mapping. Chances are you’ll use a special identify of alternative. If the Column Names Mapping question exists then Supply = #"Column Names Mappings" else Supply = null
  • The ColumnNewName step checks the contents of the Supply step which is both the Column Names Mapping desk or a null. If it’s the Column Names Mapping desk then it seems for the ColumnName parameter within the [Column Name] column throughout the Column Names Mapping desk. If it finds the matching worth then it makes use of the ColumnName parameter to filters the [Column Name]. Then it will get the corresponding worth from the [Description] column which comprises the brand new column identify, in any other case it brings the unique column identify again

The final step is to make use of the fnRenameColumnsFromRefQuery customized operate to rename the desk’s columns.

Invoking the fnRenameColumnsFromRefQuery Customized Operate

Energy Question has a operate to renamed column names in tables which is the Desk.TransformColumnNames(desk as desk, NameGenerator as operate) operate. The Desk.TransformColumnNames() operate accepts a NameGenerator as its second operand. So we are able to use our customized operate because the second operand throughout the Desk.TransformColumnNames() operate to rename all columns. The ultimate code should appear to be this:

Desk.TransformColumnNames(PREVIOUS_STEP_NAME, fnRenameColumnsFromRefQuery)

Here’s a screenshot of the column names earlier than and after renaming the columns:

Renaming columns using a reference list in Power Query
Renaming columns utilizing a reference record in Energy Question

You possibly can obtain the PBIX pattern right here.

Conclusion

If we expect what we’re doing is kind of laborious and we’re burning a whole lot of challenge time doing that, it’s good to consider a solution to automate the job. It’d look a bit advanced, complicated and time-consuming at first, however consider me, in lots of instances it’s value it and after you discover the best way you should utilize it in lots of different related situations which saves you a whole lot of time. Having stated that, there isn’t any assure that we are able to automate our state of affairs, so it might be higher to be ready for it. For example, it’s a very long time since I’m considering to automate the method of renaming all queries showing within the Question Editor, however I’m but to discover a answer for it. Right here is the problem, in some instances, we connect with the info supply, and we’ve got many tables to be loaded to the mannequin, and the desk names aren’t at all times consumer pleasant. It’s much like renaming columns however on the question stage. So should you already know the answer, please share it with the neighborhood so everybody can profit out of your efforts. On the finish of the day, we study from one another. So sharing our data is a paying ahead to the following individual.

The opposite level is to at all times keep in mind to ask different specialists for assist. We may be specialists in some areas however it’s unattainable for somebody being an skilled in the whole lot. Like in my case the shopper had an skilled who offered me with the column names mapping desk, with out his assist I couldn’t get the job completed.

As at all times, I might like to know your opinion, so please share your ideas within the remark part under.

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