Question

如何根据下拉值的变化隐藏字段。

我添加了一个名为“ A”的输入字段。我有一个下拉字段。如果我在下拉菜单中选择一个值，例如说“删除字段A”，则应删除输入字段。

我尝试了removeField。但这没有用。还有其他方法吗？或如何正确使用删除字段？

    this.appendDummyInput()
      .setAlign(Blockly.ALIGN_RIGHT)
      .appendField('Type ')
      .appendField(new Blockly.FieldDropdown(typeOptions), 'columnType');

    // if columnType = Card, show the following:
      this.appendDummyInput()
        .setAlign(Blockly.ALIGN_RIGHT)
        .appendField(' Card: ')
        .appendField(new Blockly.FieldDropdown(cardsList), 'cardValue');

    //  if columnType = view, show the following:
      this.appendDummyInput()
        .setAlign(Blockly.ALIGN_RIGHT)
        .appendField(' View ')
        .appendField(new Blockly.FieldDropdown(viewsList), 'viewValue');

Answer 1

好的，所以这里没有您的完整代码，但是我想我在这里看到了您的问题。

简短的答案是，在您提供的代码中，当您在块中选择新值时，我看不到您在回调函数中执行任何操作，也看不到您从XML保存/读取XML。可能其中一些被忽略了，但是为了不让您在注释中播放“包含更多代码”标签，我将在此处进行简要介绍。

让我为您展示一些示例代码，并逐步介绍我所做的一切，以使此案例有效：

Blockly.Blocks['mySampleBlock'] = {
    /**
     * Initiate the block. This runs before domToMutation.
     */
    init: function () {
        var typeOptions = [['Card', 'card'], ['View', 'view']];
        this.appendDummyInput()
            .setAlign(Blockly.ALIGN_RIGHT)
            .appendField('Type ')
            .appendField(new Blockly.FieldDropdown(typeOptions, this.handleTypeSelection.bind(this)), 'typeSelector');
        // Initialize the value of this.columnType (used in updateShape)
        this.columnType = this.getFieldValue('typeSelector');
        // Avoid duplicating code by running updateShape to append your appropriate input
        this.updateShape();
        //@TODO: Do other block configuration stuff like colors, additional inputs, etc. here
    },
    /**
     * This function runs each time you select a new value in your type selection dropdown field.
     * @param {string} newType This is the new value that the field will be set to.
     * 
     * Important note: this function will run BEFORE the field's value is updated. This means that if you call
     * this.getFieldValue('typeSelector') within here, it will reflect the OLD value.
     * 
     */
    handleTypeSelection: function (newType) {
        // Avoid unnecessary updates if someone clicks the same field twice
        if(this.columnType !== newType) {
            // Update this.columnType to the new value
            this.columnType = newType;
            // Add or remove fields as appropriate
            this.updateShape();
        }
    },
    /**
     * This will remove old inputs and add new inputs as you need, based on the columnType value selected
     */
    updateShape: function () {
        // Remove the old input (so that you don't have inputs stack repeatedly)
        if (this.getInput('appendToMe')) {
            this.removeInput('appendToMe');
        }
        // Append the new input based on the value of this.columnType
        if(this.columnType === 'card') {
            // if columnType = Card, show the following:
            //@TODO: define values in cardsList here
            var cardsList = [['Dummy Option','option']];
            this.appendDummyInput('appendToMe')
                .setAlign(Blockly.ALIGN_RIGHT)
                .appendField(' Card: ')
                .appendField(new Blockly.FieldDropdown(cardsList), 'cardValue');
        } else if (this.columnType === 'view') {
            //  if columnType = view, show the following:
            //@TODO: define values in viewsList here
            var viewsList = [['Dummy Option','option']];
            this.appendDummyInput()
                .setAlign(Blockly.ALIGN_RIGHT)
                .appendField(' View ')
                .appendField(new Blockly.FieldDropdown(viewsList), 'viewValue');
        }
    },
    /**
     * This function runs when saving your block to XML. This is important if you need to save your block to XML at any point and then either
     * generate code from that XML or repopulate your workspace from that XML
     */
    mutationToDom: function () {
        var container = document.createElement('mutation');
        // Do not use camelCase values for attribute names.
        container.setAttribute('column_type', this.columnType);
        // ALWAYS return container; this will be the input for domToMutation.
        return container;
    },
    /**
     * This function runs when loading your block from XML, after running init.
     * It's very important for updating your block in response to values selected in a field.
     */
    domToMutation: function (xmlElement) {
        // This attribute should match the one you used in mutationToDom
        var columnType = xmlElement.getAttribute('column_type');
        // If, for whatever reason, you try to save an undefined value in column_type, it will actually be saved as the string 'undefined'
        // If this is not an acceptable value, filter it out
        if(columnType && columnType !== 'undefined') {
            this.columnType = columnType;
        }
        // Run updateShape to append block values as needed
        this.updateShape();
    }
};

除了我的解释性评论外，还需要注意一些有关此情况的信息：

您不必严格使用我的this.columnType结构。相反，您可以将columnType值传递到updateShape中，并使用this.getFieldValue('typeSelector')或“回调”功能的输入（handleTypeSelection）。我倾向于使用此方法，因为我经常制作更复杂的代码块，每次获取适当的值都很困难或效率低下，this.whateverMyValueNameIs更容易。
同样，您可以像最初的本能一样使用this.removeInput和this.appendDummyInput来代替updateShape中的removeField和appendField。但是，如果执行此操作，则需要确保已命名输入，您打算将字段追加到字段中/从字段中删除。在大多数情况下，我倾向于仅添加/删除整个输入，因为这也使我可以更改标签等。
每当您对下拉列表的值进行任何更改时，您可能应该添加domToMutation和mutationToDom将该值保存到mutation属性中，然后将其读出并相应地更新您的块。即使您的块上没有实际的变种器，这也适用。
请注意此处的TODO注释；因为我不知道viewsList和cardsList的值，所以我没有提供它们，也没有为您提供任何其他块配置。

这可能会造成一些混乱，因此，如果有任何后续问题，请提出。我花了好一会儿才能掌握它。（不过，如果我不清楚您要做什么，我可能会要求您提供其他代码示例。）

祝你好运！

如何在Blockly中隐藏/删除字段？

1 个答案: