Using The RelativePath And Query Options With Web.Contents() In Power Query And Power BI M Code

The Web.Contents() function in M is the key to getting data from web pages and web services, and has a number of useful – but badly documented – options that make it easier to construct urls for your web service calls.

Consider the following url:

https://data.gov.uk/api/3/action/package_search?q=cows

It is a call to the metadata api (documentation here) for https://data.gov.uk/, the UK government’s open data portal, and returns a JSON document listing all the datasets found for a search on the keyword “cows”. You can make this call using Web.Contents() quite easily like so:

Web.Contents(
 "https://data.gov.uk/api/3/action/package_search?q=cows"
)

However, instead of having one long string for your url (which will probably need to be constructed in a separate step) you can use the RelativePath and Query options with Web.Contents(). They are given in the second parameter of the function and passed through as fields in a record. RelativePath adds some extra text to the base url given in the first parameter for the function, while Query allows you to add query parameters to the url, and is itself a record.

So, taking the example above, if the base url for the api is https://data.gov.uk/api we can use these options like so:

Web.Contents(
 "https://data.gov.uk/api", 
 [
  RelativePath="3/action/package_search", 
  Query=[q="cows"]
 ]
)

RelativePath is just the string “3/action/package_search” and is added to the base url. There is just one query parameter “q”, the search query, and the search term is “cows”, so Query takes a record with one field: [q=”cows”]. If you want to specify multiple query parameters you just need to add more fields to the Query record; for example:

Web.Contents(
	"https://data.gov.uk/api", 
	[
		RelativePath="3/action/package_search", 
		Query=
		[
			q="cows", 
			rows="20"
		]
	]
)

Generates a call that returns 20 results, rather than the default 10:

https://data.gov.uk/api/3/action/package_search?q=cows&rows=20

Obviously these options make it easier to construct urls and the code is much clearer, but there are also other benefits to using these options which I’ll cover in another blog post soon.

Note: at the time of writing there is a bug that causes the value given in RelativePath to be appended twice when the Web.Page() function is also used. Hopefully this will be fixed soon.

51 responses

  1. Pingback: Dew Drop - August 16, 2016 (#2310) - Morning Dew

  2. Pingback: daily 08/16/2016 | Cshonea's Blog

  3. Pingback: Web.Contents(), M Functions And Dataset Refresh Errors In Power BI – Chris Webb's BI Blog

  4. Pingback: Dynamic Web.Contents() and Power BI Refresh Errors – Data Inspirations

  5. Pingback: Implementing Basic Query Folding On A Web Service In Power Query/M And Power BI « Chris Webb's BI Blog

  6. Pingback: Credentials, Data Privacy Settings And Data Sources In Power Query/Power BI « Chris Webb's BI Blog

  7. Hi Chris, quick question which keeps puzzling us. After finding this brilliant solution of yours we proceeded but ran into a new problem. The API we are calling uses the same query option 4 times.

    The URL would be something along the lines of:

    https://domain/path?&properties=name&properties=description&properties=price&hapikey=xxxxxxxxxxxxxxxxxxxxxx

    In your example this would lead to:
    Query =
    [
    properties = “value1”,
    properties = “value2”,
    properties = “value3”,
    properties = “value4”,
    hapikey = “xxxxxxxxxxxxxxxxxxxxxx”,
    ]

    I feared this would pose a problem, knowing how standard arrays work, the last value assigned to properties would over write all previous ones. And indeed Power BI M actually warns for this problem.

    Any idea how to circumvent this?

    sincerely, Wouter

  8. Thank you very much for your reply. Unfortunately power bi encodes all data between “”, and although it skips the quotes, the ampersand and the equal sign all get encoded rendering the string unusable. I even installed Netmon to observe this from happening. (thankfully the api was reachable using http instead of https) I – again – am at a loss. Any new ideas?

  9. Hi Chris,

    Thanks for this article.

    I encounter an issue where the data from the website does not return correctly it seems if I use multiple query string.

    For example,

    this works fine – the data returns correctly (not using Query option)
    Source = Json.Document(Web.Contents(“http://useragentstring.com/?uas=”&userAgent_URLEncoded&”&getJSON=all”)),

    but this will cause failure in Scheduled Data Refresh in Power BI, so I have to use the Query option, like below.

    Source = Json.Document(Web.Contents(“http://useragentstring.com/”,[Query=[uas=userAgent_URLEncoded,getJSON=”all”]])),

    However, it seems that the data is not parsed in correctly, and I’ve got unknown values for most of the records.

    Try using
    userAgent_URLEncoded = Mozilla%2F5.0%20%28Windows%20NT%2010.0%3B%20Win64%3B%20×64%29%20AppleWebKit%2F537.36%20%28KHTML%20%20like%20Gecko%29%20Chrome%2F69.0.3497.100%20Safari%2F537.36

    Do you know why?

    Thanks

  10. We have tried using your method, and it works for PBIX and updates in the workbool, but when we upload to PBIS, and try to run the refresh there, the only APIs that will connect are those that do not use your method of breaking the relative path out from the main URL string. All of our data sources (APIs) that are called with the relative path in the main URL string work, and those where we use your method to break them out into their own relative path are unable to connect to the API for data refresh via PBIS. The same queries that work on the desktop do not connect or work in PBIS.

    • Hmm, that suggests something else is going on here. Have you turned off data privacy checks in Power BI Desktop? If so, does refresh fail when you turn on the data privacy checks?

  11. What about if the query parameter name contains a pipe?

    Like this – query_start_date|lt

    (not me, but the API i am trying to hit) – is there any way to wrap it so PowerBI accepts it? currently throws an Invalid Identifier error

  12. This worked perfectly for me but then I found that it requires a gateway. I’m doing straight web calls, any idea how to skip the gateway?

  13. I can’t make it work for any way in order to schedule refresh data. I have even check 404 errors. In Power Bi desktop works perfectly. It is azure devops api.

    I’m getting: “We reached the end of the buffer.. The exception was raised by the IDataReader interface. Table: Query1”

    let

    Capacity = (ProjectSK as text, IterationSK as text, AssignedToUserSK as text) =>

    let
    Url = Web.Contents(“https://dev.azure.com”, [RelativePath=”/[Companyname]/” & ProjectSK & “/” & “_apis/work/teamsettings/iterations/” & IterationSK & “/capacities/” & AssignedToUserSK , ManualStatusHandling={404}, Query=[#”api-version”=”5.0″]] ),
    Origen = Table.FromColumns({Lines.FromBinary(Url, null, null, 65001)}),
    #”JSON analizado” = Table.TransformColumns(Origen,{},Json.Document),
    #”Se expandió Column1″ = Table.ExpandRecordColumn(#”JSON analizado”, “Column1”, {“teamMember”, “activities”, “daysOff”, “url”, “_links”}, {“Column1.teamMember”, “Column1.activities”, “Column1.daysOff”, “Column1.url”, “Column1._links”}),
    #”Se expandió Column1.activities” = Table.ExpandListColumn(#”Se expandió Column1″, “Column1.activities”),
    #”Se expandió Column1.activities1″ = Table.ExpandRecordColumn(#”Se expandió Column1.activities”, “Column1.activities”, {“capacityPerDay”, “name”}, {“Column1.activities.capacityPerDay”, “Column1.activities.name”}),
    #”Columnas quitadas” = Table.RemoveColumns(#”Se expandió Column1.activities1″,{“Column1.teamMember”, “Column1.activities.name”, “Column1.daysOff”, “Column1.url”, “Column1._links”}),
    #”Columnas con nombre cambiado” = Table.RenameColumns(#”Columnas quitadas”,{{“Column1.activities.capacityPerDay”, “capacityPerDay”}}),
    GetMetadata = Value.Metadata(Url),
    GetResponseStatus = GetMetadata[Response.Status],
    Output = if GetResponseStatus=404 then Table.FromRecords({[capacityPerDay = 0]}) else #”Columnas con nombre cambiado”
    in
    Output

    in
    Capacity

      • It is curious how Power Bi Service is different to Desktop. I found my solution taking [CompanyName] out of relative path to join de URL parameter in Web.Content. It doesn’t have so much sense, but it is actually working.

  14. Since this albeit very useful post is written in 2016 it ends with “Note: at the time of writing there is a bug that causes the value given in RelativePath to be appended twice when the Web.Page() function is also used. Hopefully this will be fixed soon.”

    This bug seems to be ongoing still today.

    I can’t get my function to work with the Query parameter when I use Web.Page() around the Web.Contents(“url”, [Query=[term=value]])

    However it works when I use Web.Page(Web.Contents(“url/?term=value)) (No

    I really wanted to let my custom connection run through a gateway but stumbled upon the unsupported source error because of Web.Contents() function – hence me reading this post.

    Now I seem to have two problems instead of one. 😐

  15. I have a API URL which works like this :
    https://jira.company.com/rest/api/2/issue/RC-2345/worklog
    to get the data from JIRA , the param is RC-2345 in this rest is static , how can we create a similar funtion to pass the JIRAID as param , i tried the below sample function but it doesnt pass it correctly.

    = (JIRAID as text) =>
    let Source = Json.Document(Web.Contents(“https://jira.company.com/rest/api/2/issue”, [Query=[JIRAID]], [RelativePath=”worklog/”]))
    in Source

  16. Pingback: Historical Stock Price Function in Power Query - Power BI Tips and Tricks

  17. Have you ever seen an issue where it adds a “/” into the url?
    The API I’m trying to hit is something like this:
    “www.website.com/api/measures/history?metrics=metric1,metric2,metric3&project=ProjectName
    RelativePath =”?metrics=metric1,metric2,metric3&project=”
    Query=[project=ProjectName]
    The problem is that it shoots out
    http://www.website.com/api/measures/history/?metrics=metric1,metric2,metric3&project=ProjectName
    because it adds a “/” automatically before the relativepath.

  18. Pingback: Tips, Gateway, Embedding and Analysis Services – Roundup #57 – 360reports.io Power BI Videos

  19. Pingback: Power BI Auditing – 360reports.io Power BI Videos

  20. Hi Chris,
    I have been exploring using USERNAME() or USEPRINCIPALNAME() to dynamically assign the Paranmeter value in the Web.Contents query. The idea is to extract relevant data based on Power BI login user. Using RLS is possible however this alternative (if possible) will greatly reduce the number of records extracted for respective users.
    Do you think this is possible ?

  21. Chris, first of all, thanks for this incredibly helpful post! I’ve tried to follow what you have done and the code works fine in the desktop, but I’m still having problems with not being able to refresh the data when I have published to the powerbi service.

    I’m actually connecting to an ODATA service, and had to figure out how to use params with ‘$’ signs in the name, so the example below might be helpful to others doing the same thing.

    I did try and import the data using an ODATA data source, but was having problems, hence ended up going this route:

    BaseUri = “https://myurl/v1/”,
    QueryRecord =
    [ RelativePath=”tickets/”,
    Query=
    [
    token = “xxxxxxxxxx”,
    #”$select” = “id,type,origin,baseStatus,createdDate,slaSolutionDate,slaSolutionTime,resolvedIn,urgency,serviceFull,subject”,
    #”$filter” = “createdDate gt ” & FormattedDate & “-05:00 and baseStatus ne ‘Canceled'”,
    #”$top” = “1000”,
    #”$skip” = “1”
    ]
    ],
    Source = Json.Document(
    Web.Contents( BaseUri, QueryRecord )

    Anything obvious I am doing wrong?

    Thanks

    Dan

  22. Pingback: Chris Webb's BI Blog: Implementing Basic Query Folding On A Web Service In Power Query/M And Power BI Chris Webb's BI Blog

  23. Pingback: Chris Webb's BI Blog: Web.Contents(), M Functions And Dataset Refresh Errors In Power BI Chris Webb's BI Blog

  24. I have been facing this Issue for a week and tried various approaches to fix it with no positive results 🙁

    I have set a Parameter that provides the ability to make a Dynamic URL with the Following Code which would later be merged with a list-to-table Query:

    let
    Document=(Numero as number)as table =>
    let
    Source = Web.Contents(“http://www.sanaa.hn/colonias/dbo_fechas_agua_list.php?masterkey1=”&Number.ToText(Numero)&”&mastertable=dbo.barriocolonia”,[RelativePath=”Numero”]),

    #”Extracted Table From Html” = Html.Table(Source, {{“Column1”, “TABLE[id=’form_grid_8′] > TR > :nth-child(1), TABLE[id=’form_grid_8′] > * > TR > :nth-child(1)”}, {“Column2”, “TABLE[id=’form_grid_8′] > TR > :nth-child(2), TABLE[id=’form_grid_8′] > * > TR > :nth-child(2)”}, {“Column3”, “TABLE[id=’form_grid_8′] > TR > :nth-child(3), TABLE[id=’form_grid_8′] > * > TR > :nth-child(3)”}, {“Column4”, “TABLE[id=’form_grid_8′] > TR > :nth-child(4), TABLE[id=’form_grid_8′] > * > TR > :nth-child(4)”}}, [RowSelector=”TABLE[id=’form_grid_8′] > TR, TABLE[id=’form_grid_8′] > * > TR”]),
    #”Promoted Headers” = Table.PromoteHeaders(#”Extracted Table From Html”, [PromoteAllScalars=true]),
    #”Changed Type” = Table.TransformColumnTypes(#”Promoted Headers”,{{“Id Colonia”, Int64.Type}, {“Barrio o Colonia”, type text}, {“Salida de Tanque”, type text}, {“Horario”, type text}})
    in

    #”Changed Type”
    in Document

    Static example of one of the URLS would be :”http://www.sanaa.hn/colonias/dbo_fechas_agua_list.php?masterkey1=1&mastertable=dbo.barriocolonia”

    How would the Relative Path and Query solution be applied in this context to solve the Refresh Solution in the PBI Service?

    • Just Fixed it with help of a friend, turns out it was simpler than I thought:

      Source = Web.Contents(“http://www.sanaa.hn/colonias/dbo_fechas_agua_list.php?masterkey1=1&mastertable=dbo.barriocolonia”,[Query=[masterkey1=Number.ToText(Numero),mastertable=”dbo.barriocolonia”]]),

  25. Pingback: Hente data fra API’er til Power BI | Gaute Holmin - Teknologi, livet og sånt...

  26. I got a similiar problem with the upload refresh and i am unable to implement a RelativePath. Either I have a too big dimension or my syntax is not correct. How would you do this? The line without the Relative Path is

    WebCall = Json.Document(Web.Contents(URL & “/webapp/api/v1/salesOrder/?pageSize=1000&sort=-id&page=”&Text.From([Page])&””, [Headers=[AuthenticationToken=”” & token & “”, #”Content-Type”=”application/json”, Accept=”application/json”]]))

    Best regards
    Raphael Schmidt

  27. Pingback: Power BI Incremental Refresh with Web API Data Source | Data and Analytics with Dustin Ryan

  28. Pingback: Como obter dados de APIs e atualizar automaticamente - Aprenda Power BI

  29. Pingback: Resources to learn Power Query – Ninmonkey

  30. Hi Chris,
    I am having a very similar issue with trying to connect to a SharePoint.Files() source.
    I need to be able to access a set of files that over time will move from a Development SharePoint folder to an Operations folder.
    My original plan was to connect to an excel file that would contain the url pathways (root, path, file), and then load my data using parameters against that excel file.
    It works a treat in desktop, but then I get the “Dynamic data source” error once published to a workspace.
    Is it possible to use a similar “relative path” solution using SharePoint.Files() as a source?

Leave a Reply to Paul Cancel reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: