Estimated Reading : 30 minutes
PowerBi Custom connector enables you to connect to tabaqat's URLs. These URLs are used to retrieve our data and use it in building visuals.
If you are a Power User or an Advanced User of Power BI, you may have your own secret M recipes to connect to your own data sources and do complex data transformations.
Then, why don't you package them and distribute them by developing Power BI Custom Connector? There are some advantages to do it.
- You can hide all the details of M code and just expose the most important functions so that everyone can easily use it.
- Users (including you) can add another operation on top of your M code easily and they don't have to touch your code.
- You can delegate authentication to connector.
Simply install them one by one by following wizards.
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Our API returns GeoJSON format. You should be able to understand this format in order to decide which data to get and which to leave.
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Before start in PowerBi Desktop you need to get URL that gives you the data as a GeoJSON file.
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We will return two tables inside PowerBi Desktop using our tabaqat API links :
https://data.tabaqat.net/geoserver/education-and-training/ows?service=WFS&version=1.0.0&request=GetFeature&typeName=education-and-training%3Aeducation-and-training_m3wpO118771&outputFormat=application%2Fjson&access_token=
https://data.tabaqat.net/geoserver/education-and-training/ows?service=WFS&version=1.0.0&request=GetFeature&typeName=education-and-training%3Aeducation-and-training_1YjB7179859&outputFormat=application%2Fjson&access_token={access_Token}
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The two API links contains data about Riyadh region. You can get these links using tabaqat. The links are missing access token at the end of each one. If you are a registered user at tabaqat you can get your access token and paste it at the end of the link after "="
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After concate URL and access token , now you have full link that will return a GeoJSON file format that contains our data and use it in next steps .
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Don't worry if you read this and don't understand. Let us start with the steps to clarify everything
1-First navigate to tabaqat.net and create an account if you don't have one.
2-After registering click login and sign with your email and password.
3-Change language to English.
4-Click on Key then Generate Key. As a free user you have up to five keys to generate.
5-Head to Map Services and select the layer you want to load inside PowerBi and then click "Use" .
6-Click on MICROSOFT POWER BI Then copy Url that contain your Generated access token .
1-Open PowerBi Desktop and Connect to Web.
2-Paste access token from tabaqat.net that mentioned later here.
3-PowerBi will forward you automatically to Power Query editor.
4-Press on Advanced Editor.
5-Copy M code from Advanced editor and put it in sticky note because you will use later.
6-While you open PowerBI Desktop, make sure you change Data Extension policy in security settings.
Now We convert (develop) above M code into custom connector.
1-Open Visual Studio 2017 and click "Create New Project".
2-Select Data Connector Project . If you don't see this, make sure to install Power Query SDK and restart Visual Studio.
3-Name the project and press Ok.
4-Visual Studio generates many files, but you just need to pay attention to two files.
- .pq file : This is where I write code.
- .query.pq file : This is where I test the code.
5-Open pq file. The syntax should be familiar as it's M language!
1-First of all, copy and paste the Get_tabqat1 function. I place it below shared section. One difference is I use ; at the end of function. As I already show the code above, I put picture below to clarify where I put my code .
Get_tabqat1 = () as table =>
let
DefaultRequestHeaders = [
#"Accept" = "application/json;odata.metadata=minimal",
#"OData-MaxVersion" = "4.0"
],
source = Web.Contents("https://data.tabaqat.net/geoserver/transportation/transportation_rjAZr139504/ows?service=WFS&version=1.0.0&request=GetFeature&typeName=transportation_rjAZr139504&outputFormat=application%2Fjson&access_token={YOUR_ACCESS_TOKEN}&AcceptLanguages=en", [ Headers=DefaultRequestHeaders ]),
json = Json.Document(source),
value = json[value],
toTable = Table.FromList(value, Splitter.SplitByNothing(), null, null, ExtraValues.Error)
in
toTable;
2-Next, migrate the rest of the code that we mention later by replaces existing code under shared keyword. Again, I place picture below.
1-Open *.query.pq file and confirm it calls the shared function.
2-Press F5 key to start test. The M Query Output window opens and asks credential first. Set Anonymous to credential type and click Set Credential.
3-Press F5 again and you see the data comes back.
Now you build your first connector.
Last step is to deploy the connector.
1-Navigate to the project folder | bin | Debug. You can find *.mez file. There is a plan to change file extension so it could be different in the future.
2-Copy the file into C:\users\Documents\Power BI Desktop\Custom Connectors folder. Create the folder if not exists.
1-Restart Power BI Desktop and start from Get Data.
2-Search for "Custom_Connector" and you should find your connector.
3-You will see WARNNING when connecting but just continue.
4-Only anonymous authentication is available. Click Connect.
5-Load the data or continue to transform if you want.
6-If you want to see the data that loaded you will find it at the right in PowerBi.
7-Repeat all above steps with another URL with the same access token.
8-delete .mez file from Custom Connectors folder and rebuild the script ,after rebuild the script but .mez In Custom Connectors folder.
9-Restart PowerBi Desktop and connect to Custom_Connector connector again.
10-Now you want to load data from second URL !
11-Click on Transform data in PowerBi ,this step will forward you to power query editor.
12-Click on Advanced Editor advanced_editor.
13-Copy M code and press Done.
14-from New Sources Click on Blank Query .
15-Click on Advanced Editor again and paste M code in it but this time will change in the name of function Custom_Connector2 that will load the data from second URL and press Done.
16-Now you have two data sources from different URLs with the same access token.
17-Finally press on �Close & Apply� to load data in PowerBi.
18-to see data that loaded in PowerBi ,press on �Data�.
Now you are ready to build visuals using PowerBi.
19-To create Relationship between 2 tables ,press on model that appear on the left side , long prees on column that exsist in another table and match between them and finally press ok.
20-Relationship will created automatic between 2 tables ,then prees Ok.
21-Build your visuals using the data.
