Passing info from one form to another

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I'm kinda stuck and not sure how I should go about this.

I have a form where I collect some information, and the user clicks a button to save the info to a datagridview control. The problem is that the datagridview is in another form.

I initially tried to pass the information using the following code, but it won't work because the target method needs to be static, and I can't make it static (so far as I know) because that method calls another method on an object, and a static method cannot reference an object.

C#

\
        private void toolStripButton1_Click(object sender, EventArgs e)
        {
            string[] ingredient = {this.AddIngredient_Quantity.Text + " "
                                   this.AddIngredient_Unit.Text,
                                   this.AddIngredient_Ingredient.Text,
                                   this.AddIngredient_Format.Text };
            EditRecipe.addIngredient(ingredient);
        }

This code is in a form called AddIngredient.cs, and as you can see, the information is to be added to EditRecipe.cs. The following is what I have so far for code:

C#

public static void addIngredient(string[] ingredient)
{
    ingredients.Rows.Add(ingredient);
}

This cannot work because EditRecipe.ingredients is an instance of DataGridView.

How can I possibly hack this to accomplish my goal?

Posted 23-Dec-11 13:24pm

agent154

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Sergey Alexandrovich Kryukov · Accepted Answer · 2011-12-23T14:02:00

Solution 1

This is the popular question about form collaboration. The most robust solution is implementation of an appropriate interface in form class and passing the interface reference instead of reference to a "whole instance" of a Form. Please see my past solution for more detail: How to copy all the items between listboxes in two forms[^].

—SA

Posted 23-Dec-11 14:02pm

Sergey Alexandrovich Kryukov

Comments

agent154 23-Dec-11 20:28pm

I did a few CS courses a couple years back, and Interfaces were one of very few subjects that I could just not understand for the life of me. I googled it now and I think I have a bit better of an understanding, but I still have no idea how I would go about implementing such functionality between my two forms.

agent154 23-Dec-11 20:49pm

I think part of my confusion here is because Form1 calls Form2, and in Form2, changes to data are made. When hitting the save button, I need that data to be passed back to Form1. All of these examples seem to imply that the form where the data is going is being called directly. Form2 does not call Form1, it only acts as a dialog box with a save button.

agent154 23-Dec-11 21:33pm

After reading up a bit more, I still have no idea why interfaces are even necessary; they seem to offer no additional functionality, as far as I can understand.

In any event, I managed to solve the problem by passing a reference to Form1 to Form2 via 'AddIngredient form2 = new AddIngredient(this)' and then used the reference in Form2 to invoke the 'addIngredient()' method. It works as expected. Thanks anyhow.

Sergey Alexandrovich Kryukov 24-Dec-11 0:47am

I explain below why interfaces are better. Yes, they do not add any functionality, but this is not the only goal. They improve discipline which ultimately makes code more maintainable and less error-prone.
--SA

agent154 24-Dec-11 0:31am

OK, I think I have to take that back... after a ton of experimenting with inheriting, I found out that interfaces work almost exactly like inheriting a whole class, except on a smaller scale. I understand how things work now!

Thanks for the tip.

Sergey Alexandrovich Kryukov 24-Dec-11 0:46am

Nothing about scale here.

Interface behave exactly like "pure" abstract classes. Also, interfaces can be inherited by a structure, not just a class. When you work with real objects as interface references during run-time, this can be only the compile-time type, the actual run-time type of such object is always a class or structure implementing the interface.
Finally, interfaces provide the weak form of multiple inheritance: could be multiple interface bases, only zero or one base class.

In particular, the method I explained cannot be developed with just classes, without interfaces. Here is how the weak form of multiple inheritance helps: your form class is based on the System.Windows.Forms.Form and some unrelated interface at the same time. Better yet, you can write these bases in different files, totally isolated.

This way, you pass only the interface reference to the form, so you don't share too much access to the "whole" form class, which saves you from some extra errors. That's why this method is the most neat.

Is it more clear now?

Good luck,
--SA

Monjurul Habib 24-Dec-11 2:43am

5!

Sergey Alexandrovich Kryukov 24-Dec-11 16:56pm

Thank you, Monjurul.
--SA