Import data from file inside "classdef properties"

Hi all,

I'd like to understand how to do something that i find really intriguing.

I'm talking about importing data from an external file (Excel) and then assigning specific fields' values (from that file) to the variables defined within the "properties" of a "classdef" in my code. These variables are useful in different parts of the code, so that if I change the external file I can change the properties mentioned, which are automatically called inside the code itself.

I've already defined the parser for the external file, but I do not know how to integrate it into the classdef.

Your help would be greatly appreciated.

Thanks!

[Jeff Miller]

Call your parser from the constructor when you create an object of the class? Maybe pass the file name to the constructor as an argument so that different objects will have properties taken from different Excel files...

[Walter Roberson]

It depends: is it necessary that you be able to change the file while there are existing objects of the class? (If so then should the new properties affect the existing objects ?)

[slow_hand]

For Jeff: I'm trying to parse the file outside of the classdef and then pass the file to it, but it still gives me errors ...

For Walter: Ideally, each time I run the code I need to extract data from the Excel and then change the properties in the classdef...but I do not know how...

[Steven Lord]

Ideally, each time I run the code

What do you mean by "the code"?

• The class constructor?
• Each class method?
• Each file that accesses a property of the object?

What's the purpose of these properties? How do they get used in your workflow? Knowing a little more about your planned usage may help understand if there's an alternate approach that may be more efficient than your current planned approach. This may help avoid the XY problem.

[slow_hand]

To Steven: For "code" I mean exactly each file that accesses a property of the object.

For now, in the classdef, I've defined a function in methods that parses the Excel file and extracts certain properties/value/fields.

Then, in the properties section of the class, I recall these properties by writing:

propertyName = classdefName.functionName.propertyName

Where propertyName is the property extracted from the Excel, classdefName is the name assigned to the classdef and functionName is the function mentioned before.

It seems to work, however do you think it is a valid approach??

Thanks.

Answer 1

[SAI SRUJAN]

Hi,

I understand that you are facing an issue with importing data from a file to inside of 'classdef properties'.

This can be done by using the class constructor or a dedicated method to load the data when an instance of the class is created or when needed.

Below is an example of how you might structure your class to include importing data from an Excel file and assigning specific fields' values to the class properties.

classdef MyClass
    properties
        Property1
        Property2
    end
    
    methods
        function obj = MyClass(excelFilePath)
            if nargin > 0
                obj = obj.loadExcelData(excelFilePath);
            end
        end
        
        function obj = loadExcelData(obj, excelFilePath)
                data = readtable(excelFilePath);
                
                obj.Property1 = data.Field1; 
                obj.Property2 = data.Field2; 
        end
    end
end

I hope this helps!

[slow_hand]

Thank you SAI, this is exactly what I was meaning in my answer above!