Thursday, January 5, 2023

How to Filter Dates in Canvas Apps Using Greater Than/Less Than Operators

Defining the Problem

Recently I was attempting to filter an on-premise SQL table by a DateTime field using a “greater than” operator, and displaying the results in a Data Table control.  When I applied the “greater than” condition to my filter, it would return 0 results.  The crazy thing was I wasn’t seeing any errors.  So I then turned on the Monitor tool and took a look at the response of the getRows request:

{
  "duration": 1130.2,
  "size": 494,
  "status": 400,
  "headers": {
    "Cache-Control": "no-cache,no-store",
    "Content-Length": 494,
    "Content-Type": "application/json",
    "Date": "Thu, 05 Jan 2023 13:36:12 GMT",
    "expires": -1,
    "pragma": "no-cache",
    "strict-transport-security": "max-age=31536000; includeSubDomains",
    "timing-allow-origin": "*",
    "x-content-type-options": "nosniff",
    "x-frame-options": "DENY",
    "x-ms-apihub-cached-response": true,
    "x-ms-apihub-obo": false,
    "x-ms-connection-gateway-object-id": "c29ec50d-0050-4470-ac93-339c4b208626",
    "x-ms-request-id": "e127bd54-0038-4c46-9a31-ce94547c226c",
    "x-ms-user-agent": "PowerApps/3.22122.15 (Web AuthoringTool; AppName=f3d6b68b-f463-43a2-bb2b-b1ea9bd1a03b)",
    "x-ms-client-request-id": "e127bd54-0038-4c46-9a31-ce94547c226c"
  },
  "body": {
    "status": 400,
    "message": "We cannot apply operator < to types DateTimeZone and DateTime.\r\n     inner exception: We cannot apply operator < to types DateTimeZone and DateTime.\r\nclientRequestId: e127bd54-0038-4c46-9a31-ce94547c226c",
    "error": {
      "message": "We cannot apply operator < to types DateTimeZone and DateTime.\r\n     inner exception: We cannot apply operator < to types DateTimeZone and DateTime."
    },
    "source": "sql-eus.azconn-eus-002.p.azurewebsites.net"
  },
  "responseType": "text"
}

Ah, Power Apps shows no error since it returned a 400 status, but the body contains the actual error: "We cannot apply operator < to types DateTimeZone and DateTime.\r\n     inner exception: We cannot apply operator < to types DateTimeZone and DateTime.\r\nclientRequestId: e927bd54-0038-4c46-9a31-ce94547c226c".  Apparently my DateTime column in SQL does not play well with Power App’s Date Time.  After some googling I found some community posts as well:


The Solution

The last community post above suggests that I should try the DateTimeOffset column type in SQL, and after another return to the googling I found a very similar issue described by Tim Leung, describing the same thing.  Unfortunately no one documented how to do this, so here I am, documenting how to do it for you dear reader, as well as future me !  Please be warned, I’m still not sure how DateTimeOffset plays with other tools/systems, so test first!)

  1. Update the DateTime Column in SQL Server
  2. ALTER TABLE dbo.<YourTableName>
    ALTER COLUMN <YourDateColumn> datetimeoffset(0) NOT NULL;

    UPDATE dbo.<YourTableName>
    SET <YourDateColumn> = CONVERT(datetime, <YourDateColumn>) AT TIME ZONE <YourTimeZone>;

    /*
    I don't believe there is a Daylight Saving Time option to timezones, but I just happened to be in EST, not EDT, so my last line looked like this:

        SET <YourDateColumn> = CONVERT(datetime, <YourDateColumn>) AT TIME ZONE 'Eastern Standard Time';

    Use SELECT * FROM Sys.time_zone_info to find your time zone.
    */

  3. Refresh the Data source in the app

  4. In Canvas Apps Studio, click data source options menu and select Refresh
  5. Reload the app
  6. I had problems with the Data Table control I was using not applying the timezone offset correctly.  Reloading the app seemed to fix this issue.

  7. Viola!


It’s not hard, but it definitely is a headache that I would hope Microsoft will solve.



1 comment:

FW said...

Hi Daryl, Any updates on this? I'm still seeing it for filtering an on prem sql server in 2024 .