Custom API Connector - Data Source Path

PowerUser123 · ‎12-20-2022

I used this guide to create a custom connector to connect to an API that uses OAuth 2.0: https://jussiroine.com/2019/02/building-a-custom-connector-for-power-bi-that-supports-oauth2-to-visu...

I was able to set everything up successfully, however, every time I want to change the API URL, Power BI treats it as a new source. I had to setup pagination to paginate through the API results as they limit results and each pagination is a different URL string. Power BI treats each of these pages as a new source. So if I have 10 pages of results, Power BI is prompting me with the same login 10 times.

I read about data source paths and required parameters that should make Power BI understand that the base url is truly the main "source" of data thus not prompting me 10 times for credentials.

https://learn.microsoft.com/en-us/power-query/handlingauthentication#data-source-paths

I'm just not sure how to implement this in the code below?

@ImkeF

// This file contains your Data Connector logic
section OuraCloudConnector;

// OuraCloud OAuth2 values
client_id = Text.FromBinary(Extension.Contents("client_id.txt"));
client_secret = Text.FromBinary(Extension.Contents("client_secret.txt"));
redirect_uri = "https://oauth.powerbi.com/views/oauthredirect.html";
token_uri = "https://api.ouraring.com/oauth/token";
authorize_uri = "https://cloud.ouraring.com/oauth/authorize";
logout_uri = "https://login.microsoftonline.com/logout.srf";

// Login modal window dimensions
windowWidth = 720;
windowHeight = 1024;

// OAuth2 scope
scope_prefix = "";
scopes = {
    "daily"
};

[DataSource.Kind="OuraCloudConnector", Publish="OuraCloudConnector.Publish"]
shared OuraCloudConnector.Contents = (url as text) =>
    let
        source = Json.Document(Web.Contents(url))
    in
        source; 

// Data Source Kind description
OuraCloudConnector= [
    TestConnection = (dataSourcePath) => { "OuraCloudConnector.Contents", dataSourcePath },
    Authentication = [
        OAuth = [
            StartLogin=StartLogin,
            FinishLogin=FinishLogin,
            Refresh=Refresh,
            Logout=Logout
        ]
    ],
    Label = Extension.LoadString("DataSourceLabel")
];

// Data Source UI publishing description
OuraCloudConnector.Publish = [
    Beta = true,
    Category = "Other",
    ButtonText = { Extension.LoadString("ButtonTitle"), Extension.LoadString("ButtonHelp") },
    LearnMoreUrl = "https://powerbi.microsoft.com/",
    SourceImage = OuraCloudConnector.Icons,
    SourceTypeImage = OuraCloudConnector.Icons
];

// Helper functions for OAuth2: StartLogin, FinishLogin, Refresh, Logout
StartLogin = (resourceUrl, state, display) =>
    let
        authorizeUrl = authorize_uri & "?" & Uri.BuildQueryString([
            response_type = "code",
            client_id = client_id,  
            redirect_uri = redirect_uri,
            state = state,
            scope = GetScopeString(scopes, scope_prefix)
        ])
    in
        [
            LoginUri = authorizeUrl,
            CallbackUri = redirect_uri,
            WindowHeight = 720,
            WindowWidth = 1024,
            Context = null
        ];

FinishLogin = (context, callbackUri, state) =>
    let
        // parse the full callbackUri, and extract the Query string
        parts = Uri.Parts(callbackUri)[Query],
        // if the query string contains an "error" field, raise an error
        // otherwise call TokenMethod to exchange our code for an access_token
        result = if (Record.HasFields(parts, {"error", "error_description"})) then 
                    error Error.Record(parts[error], parts[error_description], parts)
                 else
                    TokenMethod("authorization_code", "code", parts[code])
    in
        result;

Refresh = (resourceUrl, refresh_token) => TokenMethod("refresh_token", "refresh_token", refresh_token);

Logout = (token) => logout_uri;

// see "Exchange code for access token: POST /oauth/token" at https://cloud.ouraring.com/docs/authentication for details
TokenMethod = (grantType, tokenField, code) =>
    let
        queryString = [
            grant_type = "authorization_code",
            redirect_uri = redirect_uri,
            client_id = client_id,
            client_secret = client_secret
        ],
        queryWithCode = Record.AddField(queryString, tokenField, code),

        tokenResponse = Web.Contents(token_uri, [
            Content = Text.ToBinary(Uri.BuildQueryString(queryWithCode)),
            Headers = [
                #"Content-type" = "application/x-www-form-urlencoded",
                #"Accept" = "application/json"
            ],
            ManualStatusHandling = {400} 
        ]),
        body = Json.Document(tokenResponse),
        result = if (Record.HasFields(body, {"error", "error_description"})) then 
                    error Error.Record(body[error], body[error_description], body)
                 else
                    body
    in
        result;

Value.IfNull = (a, b) => if a <> null then a else b;

GetScopeString = (scopes as list, optional scopePrefix as text) as text =>
    let
        prefix = Value.IfNull(scopePrefix, ""),
        addPrefix = List.Transform(scopes, each prefix & _),
        asText = Text.Combine(addPrefix, " ")
    in
        asText;
        

OuraCloudConnector.Icons = [
    Icon16 = { Extension.Contents("OuraCloudConnector16.png"), Extension.Contents("OuraCloudConnector20.png"), Extension.Contents("OuraCloudConnector24.png"), Extension.Contents("OuraCloudConnector32.png") },
    Icon32 = { Extension.Contents("OuraCloudConnector32.png"), Extension.Contents("OuraCloudConnector40.png"), Extension.Contents("OuraCloudConnector48.png"), Extension.Contents("OuraCloudConnector64.png") }
];