设计者必须创建一个......的实例,因为该类型被声明为abstract

Visual Studio中抱怨:警告1名设计者必须创建类型"RentalEase.CustomBindingNavForm"的一个实例,但它不能因为类型声明为抽象的.

Visual Studio不允许我访问表单的Designer.该类已经实现了CustomBindingNavForm中的所有抽象方法.CustomBindingNavForm提供了一些具体和抽象的函数.

有没有解决的办法？

这是班级:

 public abstract class CustomBindingNavForm : SingleInstanceForm {     

        //Flags for managing BindingSource
        protected bool isNew = false;
        protected bool isUpdating = false;

        /// 

        /// This is so that when a new item is added, it sets isNew and firstPass to true. The Position Changed Event will look for
        /// firstPass and if it is true set it to false. Then on the next pass, it will see it's false and set isNew to false.
        /// This is needed because the Position Changed Event will fire when a new item is added.
        /// 
        protected bool firstPass = false;


        protected abstract bool validateInput();
        protected abstract void saveToDatabase();


        //manipulating binding
        protected abstract void bindingSourceCancelResetCurrent();
        protected abstract void bindingSourceRemoveCurrent();
        protected abstract void bindingSourceMoveFirst();
        protected abstract void bindingSourceMoveNext();
        protected abstract void bindingSourceMoveLast();
        protected abstract void bindingSourceMovePrevious();
        protected abstract void bindingSourceAddNew();

        public void bindingNavigatorMovePreviousItem_Click(object sender, EventArgs e) {
            if (validateInput()) {
                bindingSourceMovePrevious();
            } else {
                DialogResult cont = MessageBox.Show(null, "There are errors in your data. Click Cancel to go back and fix them, or ok to continue. If you continue, changes will not be saved.", "Continue?", MessageBoxButtons.OKCancel, MessageBoxIcon.Question, MessageBoxDefaultButton.Button2);
                if (cont == DialogResult.OK) {
                    if (isNew) {
                        bindingSourceRemoveCurrent();
                        isNew = false;
                    } else {
                        bindingSourceCancelResetCurrent();
                        bindingSourceMovePrevious();
                    }
                }
            }
        }

        public void bindingNavigatorAddNewItem_Click(object sender, EventArgs e) {
            if (validateInput()) {
                saveToDatabase();
                bool temp = isUpdating;
                isUpdating = true;
                bindingSourceAddNew();
                isUpdating = temp;

                isNew = true;
                firstPass = true;
            } else {
                DialogResult cont = MessageBox.Show(null, "There are errors in your data. Click Cancel to go back and fix them, or ok to continue. If you continue, changes will not be saved.", "Continue?", MessageBoxButtons.OKCancel, MessageBoxIcon.Question, MessageBoxDefaultButton.Button2);
                if (cont == DialogResult.OK) {

                    if (isNew) {
                        bindingSourceRemoveCurrent();
                        isNew = false;
                    } else {
                        bindingSourceCancelResetCurrent();
                    }

                    bool temp = isUpdating;
                    isUpdating = true;
                    bindingSourceAddNew();
                    isUpdating = temp;

                    isNew = true;
                    firstPass = true;
                }
            }
        }

        public void bindingNavigatorMoveFirstItem_Click(object sender, EventArgs e) {
            if (validateInput()) {
                bindingSourceMoveFirst();
            } else {
                DialogResult cont = MessageBox.Show(null, "There are errors in your data. Click Cancel to go back and fix them, or ok to continue. If you continue, changes will not be saved.", "Continue?", MessageBoxButtons.OKCancel, MessageBoxIcon.Question, MessageBoxDefaultButton.Button2);
                if (cont == DialogResult.OK) {
                    if (isNew) {
                        bindingSourceRemoveCurrent();
                        isNew = false;
                    } else {
                        bindingSourceCancelResetCurrent();
                    }
                    bindingSourceMoveFirst();
                }
            }
        }

        public void bindingNavigatorMoveNextItem_Click(object sender, EventArgs e) {
            if (validateInput()) {
                bindingSourceMoveNext();
            } else {
                DialogResult cont = MessageBox.Show(null, "There are errors in your data. Click Cancel to go back and fix them, or ok to continue. If you continue, changes will not be saved.", "Continue?", MessageBoxButtons.OKCancel, MessageBoxIcon.Question, MessageBoxDefaultButton.Button2);
                if (cont == DialogResult.OK) {
                    if (isNew) {
                        bindingSourceRemoveCurrent();
                        isNew = false;
                    } else {
                        bindingSourceCancelResetCurrent();
                    }
                    bindingSourceMoveNext();
                }
            }
        }
    }

Allen Rice.. 29

我还没有看到城市马铃薯(它的下来)的内容,但是Me和Smelch提出了一个解决方案. Form它本身继承自一个抽象类,所以他们不告诉你的是它只有第一级继承不能抽象,第二级就可以了.

从那里它只是在中间有一个空类并包裹#if debug表格声明的问题,你很高兴去.只需确保在发布模式下发布并在调试模式下进行设计(这是非常典型的).

在设计(调试)和构建(发布)时,您将获得完整的设计器支持和真正的抽象基类,因为每次它最终都使用您的抽象基类.

完整的解释和答案就在这里

我还没有看到城市马铃薯(它的下来)的内容,但是Me和Smelch提出了一个解决方案. Form它本身继承自一个抽象类,所以他们不告诉你的是它只有第一级继承不能抽象,第二级就可以了.

从那里它只是在中间有一个空类并包裹#if debug表格声明的问题,你很高兴去.只需确保在发布模式下发布并在调试模式下进行设计(这是非常典型的).

在设计(调试)和构建(发布)时,您将获得完整的设计器支持和真正的抽象基类,因为每次它最终都使用您的抽象基类.

完整的解释和答案就在这里