Display images from A database

[PauldePaor]

LabVIEW 2013 

SQL Server 2012

 

I would like to read an image path from a SQL database and display the image on the front panel in LabVIEW. The database side works ok but when I run the VI i get an error saying Error 7 file not found. I have checked the directory and the path is correct. I have attached a screenshot of the VI and error.

[hooovahh]

Go ahead and type in that path on your windows machine into Run or the Explorer path.  I'm guessing that it won't work because your path contains spaces between each character, some non printable characters, and characters before the drive letter.  Looks like something went wrong with your read and conversion to a path.

[Tim_S]

Hrm... it looks like you need an index array in the data from the query. Also, is the string stored as unicode in the database?

[PauldePaor]

I have checked the string in the windows explorer the path works ok. C:UsersconorDesktopLabview DemosDatabase GeneratorImagesFilm3 that is the current path but when its read from the database it puts in those extra symbols.The string is stored as a varchar(max) in the database to hold the paths to the images. 

[ShaunR]

You are forcing LabVIEW to interpret a 2D array as a string. It isn't. It's a 2D array and because you are unflattening, you are getting ll the array index info in the string..

Use the index array to obtain a single element from the array returned by the SELECT function. Then use the Variant to Data primitive to convert it to a string.

 

Unflattening requires that the data was stored as flattened to begin with. I expect it wasn't.

[PauldePaor]

Hi ShaunR thanks for your reply when I insert the index array vi and run it I get error 91 occured at variant to data in my vi name.

 

Possible reason(s):

 

LabVIEW:  The data type of the variant is not compatible with the data type wired to the type input.

[Rolf Kalbermatter]

Hi ShaunR thanks for your reply when I insert the index array vi and run it I get error 91 occured at variant to data in my vi name.

 

Possible reason(s):

 

LabVIEW:  The data type of the variant is not compatible with the data type wired to the type input.

 

Without knowing how the data got stored into the database first, it will be very hard to come up with a good idea. Was the path flattened and then stored as string?

You basically have to reverse that operation exactly to have any chance of getting a sensible result. The idea about using index array from Shaun is however definitely the first step in this. Your query returns an array of values and you want to get the single value in the query result first before you do any other manipulation to get back at your path.

[drjdpowell]

Hi ShaunR thanks for your reply when I insert the index array vi and run it I get error 91 occured at variant to data in my vi name.

Show another picture of what you are doing.  Shaun’s idea should work.

[CRoebuck]

I have checked the string in the windows explorer the path works ok. C:UsersconorDesktopLabview DemosDatabase GeneratorImagesFilm3 that is the current path but when its read from the database it puts in those extra symbols.The string is stored as a varchar(max) in the database to hold the paths to the images. 

 

If you change the data type of this field in the database to nvarchar(max) do you still get the same issue ? 

 

If you set a field to be varchar(x) then the string stored there will be x in length even if the string originally stored was shorter. When you query the database you will get back a string of length x. Using nvarchar will store a variable length string up to length x.

[drakhri]

 

If you flattened the data going into the DB you will want to unflatten it coming out.

 

If you set the condition on the select exactly one element, you can index 0,0 of the 2d array and have your specific img. 

Edited April 21, 2014 by drakhri