Categories
Cheatsheet Power BI Power Query References And Cheat Sheets

Power Query Custom Functions – Cheat Sheet

Web Requests

Web.Contents without Refresh Errors

The main cause of Web.Contents not refreshing can be fixed by adding the options[Query] and options[RelativeaPath] parameters. (The UI doesn’t create them for you)

This example uses https://www.metaweather.com/api/location/search?query=london See more: Skip Test Connection

// lookup city GUID - simplified
let
    exampleUrl = "https://www.metaweather.com/api/location/search?query=london",
    Headers = [
        Accept="application/json"
    ],
    BaseUrl = "https://www.metaweather.com",
    Options = [
        RelativePath = "/api/location/search",
        Headers = Headers,
        Query = [
            query = "london"
        ],
        ManualStatusHandling = {400, 404}
    ],
    // wrap 'Response' in 'Binary.Buffer' if you are using it multiple times
    response = Web.Contents(BaseUrl, Options),
    buffered = Binary.Buffer(response),
    response_metadata = Value.Metadata(response),
    status_code = response_metadata[Response.Status],
    final_result =
        if List.Contains({400, 404}, status_code) then response_metadata
        else buffered,
    from_json = Json.Document(final_result),
    #"weather record" = from_json{0}
in
    #"weather record"

Handling Specific HTTP Error Status Codes

You can filter results based on the status code, instead of getting errors.
See more: override default error handling, and the example wait-for loop

/* web request, act based on the HTTP Status Code returned
see more:
    override default error handling: https://docs.microsoft.com/en-us/power-query/handlingstatuscodes
    example wait-for loop: https://docs.microsoft.com/en-us/power-query/waitretry#manualstatushandling
*/
let
    WikiRequest = (pageName as text) as any =>
        let
            BaseUrl = "https://en.wikipedia.org/wiki",
            Options = [
                RelativePath = pageName,
                ManualStatusHandling = {400, 404}
            ],
            // wrap 'Response' in 'Binary.Buffer' if you are using it multiple times
            response = Web.Contents(BaseUrl, Options),
            buffered = Binary.Buffer(response),
            response_metadata = Value.Metadata(response),
            status_code = response_metadata[Response.Status],
            final_result = [
                buffered = buffered,
                response_metadata = response_metadata
            ]
        in
            final_result,
    Queries = {"Cat", "DoesNot Exist fake page"},
    Items = List.Transform(
        Queries,
        each WikiRequest( _ )
    ),
    ResponseTable = Table.FromRecords(
        Items,
        type table[buffered = binary, response_metadata = record], MissingField.Error
    ),

    #"Expanded HTTP Status Codes" = Table.ExpandRecordColumn(ResponseTable, "response_metadata", {"Response.Status"}, {"Response.Status"}),
    #"Changed Type" = Table.TransformColumnTypes(#"Expanded HTTP Status Codes",{{"Response.Status", Int64.Type}})
in
    #"Changed Type"

WebRequest: Wrapper with Better Defaults

You can get the full file with extra comments: WebRequest.pq

    let
        /*
        Example using this url:
            (https://www.metaweather.com/api/location/search?lattlong=36.96,-122.02)

            WebRequest(
                "https://www.metaweather.com",
                "api/location/search",
                [ lattlong = "36.96,-122.02" ]
            )

        Details on preventing "Refresh Errors", using 'Query' and 'RelativePath':
            - Not using Query and Relative path cause refresh errors:
                (https://blog.crossjoin.co.uk/2016/08/23/web-contents-m-functions-and-dataset-refresh-errors-in-power-bi/)

            - You can opt-in to Skip-Test:
                (https://blog.crossjoin.co.uk/2019/04/25/skip-test-connection-power-bi-refresh-failures/)

            - Debugging and tracing the HTTP requests
                (https://blog.crossjoin.co.uk/2019/11/17/troubleshooting-web-service-refresh-problems-in-power-bi-with-the-power-query-diagnostics-feature/)

        */
        WebRequest = (
            staticPath as text,                 // domain
            relativePath as text,               // basically use everything after ".com" to "?"
            optional query as nullable record,  // url query string
            optional asRaw as nullable logical, // use true if content is not Json
            optional headers as nullable record // optional HTTP headers as a record
        ) as any =>
            let
                query = query ?? [],
                asRaw = asRaw ?? false, // toggles calling Json.Document() or not
                headers = headers ?? [
                    Accept="application/json"
                ],

                baseUrl = staticPath,
                options = [
                    RelativePath = relativePath,
                    Headers = headers,
                    Query = query
                    // optionally toggle handling errors for specific HTTP Status codes
                    // ManualStatusHandling = {400, 404}
                ],
                // wrap 'Response' in 'Binary.Buffer' if you are using it multiple times
                response = Web.Contents(staticPath, options),
                metadata = Value.Metadata(response),
                buffered = Binary.Buffer(response),
                result = Json.Document(buffered)
            in
                [
                    response = if asRaw then buffered else result,
                    status_code = metadata[Response.Status],
                    metadata = metadata
                ]
    in
        WebRequest

Chaining Web.Contents to Merge Many Queries

    let 
        response_locations = WebRequest(
            "https://www.metaweather.com",
            "api/location/search",
            [ lattlong = "36.96,-122.02" ]
        ),
        location_schema = type table[
            distance = number, title = text,
            location_type = text, woeid = number, latt_long = text
        ],
        cityListing = Table.FromRecords(response_locations[response], location_schema, MissingField.Error),
        
        city_mergedRequest = Table.AddColumn(
            cityListing,
            "LocationWeather",
            (row as record) as any =>
                let
                    woeid = Text.From(row[woeid]),
                    response = WebRequest(
                        "https://www.metaweather.com",
                        "api/location/" & woeid,
                        []
                    )
                in
                    response,
            type any
        )
    in
        city_mergedRequest

Html.Table – Parsing with CSS Selectors

Select a Single Element: an Image, url, text, etc…

This fetches the current heading text on the blog

let
    Url = "https://powerbi.microsoft.com/en-us/blog/",
    Response = Web.Contents( Url ),
    /*
    note: normally do not pass dynamic urls like this, see cheatsheet on preventing refresh errors
    Non-tabular scraping like Images or any single elements, does not use a "RowSelector"

    This CSS Selector finds exactly one element, the Page's Header Text

        .section-featured-post .text-heading1 a
    */
    HeaderText = Html.Table(
        Response,
        {
            { "Page Header", ".section-featured-post .text-heading1 a" }
        }
    )
in
    HeaderText

Parsing Element’s Attributes

let
    Url = "https://powerbi.microsoft.com/en-us/blog/",
    Response = Web.Contents( Url ),
    /*
    The 3rd argument in "columnNameSelectorPairs" is the transformation function.
    by default it uses:

            each _[TextContent]
    */
    HeaderAsElement = Html.Table(
        Response,
        { { "Link", ".section-featured-post .text-heading1 a", each _ } }
    ),

    ElementRecord = Table.ExpandRecordColumn(
        HeaderAsElement, "Link",
        {"TagName", "TextContent", "Attributes"}, {"TagName", "TextContent", "Attributes"}
    ),

    ExpandedAttributes = Table.ExpandRecordColumn(
        ElementRecord, "Attributes",
        {"href", "rel", "title"}, {"attr.href", "attr.rel", "attr.title"}
    )
in
    ExpandedAttributes

Select Tables using your own CSS Selectors

CSS Row Selector
Results of the RowSelector
CSS Column Selector
Results of columnNameSelectorPairs
// Docs on Enum
let
    Source = "https://docs.microsoft.com/en-us/previous-versions/dynamics/ax-2012/reference/gg841505(v=ax.60)",
    // note: normally do not pass dynamic urls like this, see cheatsheet on preventing refresh errors
    Response = Web.BrowserContents( Source ),
    /*

        Think of "RowSelector" as selecting a table row
        Then for every row, you select "columns" using the "columnNameSelectorPairs" selector
        The combination gives you a table cell.

        For more on CSS Selectors, see: 
    */

    columnNameSelectorPairs = {
        // column names don't matter here, since I'm using .PromoteHeaders
        { "Column1", "TABLE.table > * > TR > :nth-child(1)" },
        { "Column2", "TABLE.table > * > TR > :nth-child(2)" },
        { "Column3", "TABLE.table > * > TR > :nth-child(3)" }
    },

    t1 = Html.Table(
            Response, columnNameSelectorPairs,
            [RowSelector = "TABLE.table > * > TR"]
    ),

    t2 = Table.PromoteHeaders( t1, [PromoteAllScalars = true] ),
    FinalTable = Table.TransformColumnTypes(
            t2,
            { { "Name", type text }, { "Value", Int64.Type }, { "Description", type text} }
        )
in
    FinalTable

SQL Native Query

Parameterized SQL queries with Value.NativeQuery()

let
    Source = Sql.Database("localhost", "Adventure Works DW"),
    Test = Value.NativeQuery(
        Source,
        "SELECT * FROM DimDate 
        WHERE EnglishMonthName=@MonthName",
        [
            MonthName = "March",
            DayName = "Tuesday"
        ]
    )
in
    Test

Other

Cartesian Product

Table Cartesian Product
let    
    #"Add Column Pair2" = Table.AddColumn(
        Table_Pairs1, "Pairs2",
        each Table_Pairs2,
        Table.Type
    ),
    #"Expanded Pairs" = Table.ExpandTableColumn(
        #"Add Column Pair2",
        "Pairs2",
        {"Color", "Property"},
        {"Color", "Property"}
    )
in
    #"Expanded Pairs"

Details: https://radacad.com/cartesian-product-in-power-query-multiply-all-sets-of-all-pairs-in-power-bi

Convert Table to JSON

TableTo_Json = (source as table, optional encoding as nullable number) as text =>
        let
            encoding = if encoding <> null then encoding else TextEncoding.Utf8,
            bin = Json.FromValue(source, encoding),
            jsonAsText = Text.FromBinary(bin, encoding)
        in
            jsonAsText
Animals = #table(
    {"Animal", "Id"},
    {{"Cat", 1}, {"Turtle", 2}} ),
TableTo_Json( Animals )

Json output:

[{"Animal":"Cat","Id":1},{"Animal":"Turtle","Id":2}]

Converting a list of items to a CSV string

let
    // Converts a list of any type to text. Works well on most types
    // although to support all cases, it requires more logic
    mixedList = {4, "cat", #date(1999,5,9), 0.4},
    ListAsText = List.Transform(mixedList, each Text.From(_)),
    CsvText = Text.Combine( ListAsText, ", ")
in
    //output: "4, cat, 5/9/1999, 0.4"
    CsvText 

Functions

Using Optional Parameters with Default Values

The Null_coalescing_operator ?? simplifies default values.
encoding will be set to what the user passed, unless it’s null. In that case, it is set to TextEncoding.Utf8

let
    Read_Json = (json as any, encoding as nullable number) as any =>
        // calls Json.Document, using UTF8 by default
        let
            encoding = encoding ?? TextEncoding.Utf8,
            result = Json.Document(json, encoding)
        in
            result
in
    Read_Json

Mapping Function Calls based on Type

Caller chooses which type of conversioin to use, based on type names { date, datetime, datetimezone }

let
    // 1] get a `type` from caller
    // 2] return a difference function based on the type
    GetTransformByType = (_type as type) as function =>
        let
            // originally from: 
            func_transform = 
                 if (Type.Is(_type, type date)) then Date.From
            else if (Type.Is(_type, type datetime)) then DateTime.From
            else if (Type.Is(_type, type datetimezone)) then DateTimeZone.From
            else (t) => t // else return self
        in
            func_transform,

    nowDtz = DateTimeZone.LocalNow(),    

    // invoke in 2 steps
    toDate = GetTransformByType(type date),
    callDate = toDate( DateTimeZone.FixedLocalNow() ),

    // create, and invoke functions
    Results = [
        asDate = (GetTransformByType(type date))( nowDtz ),
        asDateTime = (GetTransformByType(type datetime))( nowDtz ),
        asDateTimeZone = (GetTransformByType(type datetimezone))( nowDtz )
    ]
in
    Results
Categories
Cheatsheet Command Line Excel Power BI Power Query PowerShell

Big List of Cheat sheets and References

Web

XPath

OData

HTTP

Other: Web

Encoding

Unicode.org

Emoji

Table of Contents: Emoji Charts Table

Misc

Programming and Languages

PowerShell

gist/vexx32/PowershellLoopBehavior.md

Power Query

Dotnet / .Net

Apps

VS Code

Firefox

Other: Apps

Categories
PowerShell Quick Tips

Creating a Discord Webhook in a few lines of PowerShell

Discord Web Hooks are easier than you’d think. It uses a regular `HTTP` web request .

Step1: Creating your webhook url

Go to: Server Settings -> Integrations -> View Webhooks
Then click create webhook.

Choose a name, the channel, then copy webhook url

Step2: Invoke-RestMethod

$webhookUri = 'https://discord.com/api/YourWebhookUrlHere'

$Body = @{
  'username' = 'Nomad'
  'content' = 'https://memory-alpha.fandom.com/wiki/Nomad'
}
Invoke-RestMethod -Uri $webhookUri -Method 'post' -Body $Body

Success!

Docs

There are optional webhook arguments to customize the output: https://discord.com/developers/docs/resources/webhook#execute-webhook

Comparison with curl

I tried making curl easier to read by splitting content, and pipe so that you don’t have to manually escape Json

$Json = @{ 'username' = 'Nomad'; 'content' = 'https://memory-alpha.fandom.com/wiki/Nomad' } | ConvertTo-Json -Compress

$Json | curl -X POST -H 'Content-Type: application/json' -d '@-' $webhookUri

Categories
Command Line

Improving ‘diff’ readability on Windows | Tip

The output of diff -q path1 path2 is pretty verbose. This function

  • Converts full paths to relative
  • Differences are red.

Missing ‘diff’ ?

If git is installed, you may need to update your %PATH% environment variable.

# in your profile
$Env:Path = "$Env:ProgramFiles\Git\usr\bin", $Env:Path -join ';'

Stand-Alone function Compare-Directory

This is an isolated version of Ninmonkey.Console: Compare-Directory . I removed all dependencies except coloring is provided by the module PoshCode/Pansies.

function Invoke-NativeCommand {
    <#
    .synopsis
        wrapper to both call 'Get-NativeCommand' and invoke an argument list
    .example
        PS> # Use the first 'python' in path:
        Invoke-NativeCommand 'python' -Args '--version'
    #>

    param(
        # command name: 'python' 'ping.exe', extension is optional
        [Parameter(Mandatory, Position = 0)]
        [string]$CommandName,

        # Force error if multiple  binaries are found
        [Parameter()][switch]$OneOrNone,

        # native command argument list
        [Alias('Args')]
        [Parameter(Position = 1)]
        [string[]]$ArgumentList
    )

    $binCommand = Get-NativeCommand $CommandName -OneOrNone:$OneOrNone -ea Stop
    & $binCommand @ArgumentList
}

function Compare-Directory {
    <#
    .SYNOPSIS
    Compare Two directories using 'diff'
    .EXAMPLE
    Compare-Directory 'c:\foo' 'c:\bar\bat'
    #>
    [Alias('DiffDir')]
    param(
        # Path1
        [Parameter(Mandatory, Position = 0)]
        [string]$Path1,

        # Path2
        [Parameter(Mandatory, Position = 1)]
        [string]$Path2,

        # Output original raw text?
        [Parameter()][switch]$OutputRaw
    )

    $Base1 = $Path1 | Get-Item -ea Stop
    $Base2 = $Path2 | Get-Item -ea Stop
    $Label1 = $Base1 | Split-Path -Leaf | New-Text -fg 'green'
    $Label2 = $Base2 | Split-Path -Leaf | New-Text -fg 'yellow'

    "Comparing:
        Path: $Path1
        Path: $Path2
    " | Write-Information

    $stdout = Invoke-NativeCommand 'diff' -args @(
        '-q'
        $Base1
        $Base2
    )

    $outColor = $stdout
    $outColor = $outColor -replace [regex]::Escape($path1), $Label1
    $outColor = $outColor -replace [regex]::Escape($path2), $Label2
    $outColor = $outColor -replace 'Only in', (New-Text 'Only In' -fg 'red')
    $outColor = $outColor -replace 'Differ', (New-Text 'Differ' -fg 'red')

    if ($OutputRaw) {
        h1 'Raw' | Write-Information
        $stdout
        return
    }

    $outColor
}

function Get-NativeCommand {
    <#
    .synopsis
        wrapper that returns Get-Item on a native command
    .example
        # if you want an error when multiple options are found
        PS> Get-NativeCommand python -OneOrNone
    .example
        # note: this is important, $cmdArgs to be an array not scalar for '@' usage
        $binPy = Get-NativeCommand python
        $cmdArgs = @('--version')
        & $binPy @cmdArgs
    .example
    #>
    [cmdletbinding()]
    param(
        # Name of Native .exe Application
        [Parameter(Mandatory, Position = 0, ValueFromPipeline)]
        [object]$CommandName,

        # One or None: Raise errors when there are more than one match
        [Parameter()][switch]$OneOrNone
    )

    process {
        try {
            $query = Get-Command -Name $CommandName -All -CommandType Application -ea Stop
            | Sort-Object Name

        } catch [CommandNotFoundException] {
            Write-Error "ZeroResults: '$CommandName'"
            return
        }

        if ($OneOrNone -and $query.Count -gt 1) {
            $query | Format-Table -Wrap -AutoSize -Property Name, Version, Source
            Write-Error "OneOrNone: Multiple results for '$CommandName'"
            return
        }

        if ($query.Count -gt 1) {
            $query = $query | Select-Object -First 1
        }

        Write-Debug "Using Item: $($query.Source)"
        $query
    }
}
Categories
Command Line PowerShell Quick Tips References And Cheat Sheets

Easy way to cache results on the Command Line | Power Shell Tip

Sometimes you’ll need to run a command with the same input with different logic.
This can be a hassle using a slow command like Get-ADUser or Get-ChildItem on a lot of files like ~ (Home) with -Depth / -Recurse

ls ~ -Depth 4 | Format-Table Name

PowerShell 7.0+

Powershell 7 added the Ternary Operator, and several operators for handling $null values.

All of these examples will only run Get-ChildItem the first time. Any future calls are cached.

Null-Coalesce ??= Assignment Operator

This is my favorite on the Command line. The RHS (Right Hand Side) skips evaluation if the left side is not $null

$AllFiles ??= ls ~ -Depth 4

Using the Null-Coalesce ?? Operator

$AllFiles = $AllFiles ?? ( ls ~ -Depth 4  )

Ternary Operator ? whenTrue : WhenFalse

$allFiles = $allFiles ? $allFiles : ( ls ~ -Depth 4 )

Windows PowerShell and Powershell < 7

Windows Powershell can achieve the same effect with an if statement

if(! $AllFiles) { $AllFiles = ls ~ -Depth 4 }
Categories
Power BI Power Query

Web.Contents: Using Dynamic and Duplicate key names in a Query

Power BI Discord asked the question:
> How do you use duplicate keys, and dynamic urls with Web.Contents ?
(They were using a web API that required duplicate keys)
After I wrote this, Chris Webb found an easier solution.

Requirements

  1. You can’t use a regular record because keys must be distinct. Query = [ Key1 = 1, Key1 = 10] will throw an error.
  2. You can’t put the **dynamic url** in the first argument Web.Contents or else refreshes can break

I built a RelativePath by Uri-escaping a list.

Building RelativePath by Uri-escaping a list

The final query will request the url: https://www.google.com/search?q=dog&q=cat
This function generates the query string q=dog&q=cat

This Input"q", { "dog", "cat" }
Will Returnq=dog&q=cat
let
    QueryStr_UsingDuplicateKeys = (key as text, values as list) as text =>
    // values are the 'value' of 'key'-> 'value' pairs
        let
            escapedList = List.Transform(
                values,
                each 
                    key & "=" & Uri.EscapeDataString( Text.From(_) )
            ),    
            joinedArgs = Text.Combine(escapedList, "&")
        in
            joinedArgs
in
    QueryStr_UsingDuplicateKeys

Now you can use Web.Contents as normal.

let
    BaseUrl = "https://www.google.com",
    queryStr = QueryStr_UsingDuplicateKeys(
        "q", {"dog", "cat"}
    ),
    Options = [
        RelativePath = "/search?" & queryStr,
        Headers = [ Accept="application/json" ]
    ],
    response_binary = Web.Contents(BaseUrl, Options)
in
    response_binary

Note: BaseUrl is for the static part of the url. Everything else should be in options[RelativePath] or options[Query] See docs: Web.Contents for details.

Easier Solution

First try Chris’s method where you use Query‘s Key-Value pairs a list
Results may vary. If it does not work, you can try this method.
I have not seen Query publicly documented.

Query = [
    q = {"dog", "cat"}
]

Tips from Chris Webb

Using Optional Parameters with Query

Chris has a tip to optionally use null query parameters.
If set to an empty list, {} — the request drops the parameter.
Web.Contents(
    "http://jsonplaceholder.typicode.com/comments",
    [Query = [postId = {}] ]
)

Which results in the url: http://jsonplaceholder.typicode.com/comments
This is a good place to use Power Query‘s null coalesce operator (Which isn’t in the official docs)

Query = [postId = myPostId ?? {}]

Capturing HTTP Requests without Fiddler

The Query Editor is an alternate to using Fiddler to capture web requests.
Categories
Power BI Power Query Quick Tips

Preserving Types When using “Add Custom Column” in Power Query

The default UI sets your column to type any.

You can use the optional argument of Table.AddColumn to set it to number
Or you can declare your function’s return type

Why doesn’t the original [Num] * 2 work?

Powerquery does not know what type will be returned by your function. That’s because each is by definition a function that returns type any

See More

Categories
PowerShell Quick Tips What's New

PowerShell : Prefixing lines with the Pipe operator |

There’s a lot of ways to use line continuations in Windows Powershell without backticks . Powershell added a new one, the | pipe operator. It’s cleaner to read, and makes it easier to insert, delete, or toggle comments on the console.

Now you can write:

# Powershell
ls | sort Length
| Select -First 10
| ft Name, Length

Instead of piping on line endings

# Windows Powershell
ls | sort Length |
Select -First 10 |
ft Name, Length

# or
ls | sort Length | Select -First 10 | ft Name, Length