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添加向下钻取支持

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当视觉对象具有层次结构时，你可以允许用户使用 Power BI 向下钻取功能显示更多详细信息。

阅读有关 Power BI 向下钻取功能的详细信息：Power BI 服务中的钻取模式。 要支持视觉对象动态启用或禁用钻取功能，请参阅动态向下钻取控件。

在视觉对象中启用向下钻取支持

若要在视觉对象中支持向下钻取操作，请向 capabilities.json 添加一个名为“drill-down”的新字段。 此字段有一个名为 roles 的属性，其中包含要对其启用向下钻取操作的 dataRole 的名称。

    "drilldown": {
        "roles": [
            "category"
        ]
    }

注意

向下钻取 dataRole 必须为 Grouping 类型。 必须将 dataRole 条件中的 max 属性设置为 1。

将角色添加到“向下钻取”字段后，用户可以将多个字段拖到数据角色中。

例如：

{
    "dataRoles": [
        {
            "displayName": "Category",
            "name": "category",
            "kind": "Grouping"
        },
        {
            "displayName": "Value",
            "name": "value",
            "kind": "Measure"
        }
    ],
    "drilldown": {
        "roles": [
            "category"
        ]
    },
    "dataViewMappings": [
        {
            "categorical": {
                "categories": {
                    "for": {
                        "in": "category"
                    }
                },
                "values": {
                    "select": [
                        {
                            "bind": {
                                "to": "value"
                            }
                        }
                    ]
                }
            }
        }
    ]
}

创建带有向下钻取支持的视觉对象

要创建带有向下钻取支持的视觉对象，请运行以下命令：

pbiviz new testDrillDown -t default

要创建默认示例视觉对象，请将上述 capabilities.json 的示例应用于新创建的视觉对象。

创建 div 容器的属性以保存视觉对象的 HTML 元素：

"use strict";

import "core-js/stable";
import "./../style/visual.less";
// imports

export class Visual implements IVisual {
    // visual properties
    // ...
    private div: HTMLDivElement; // <== NEW PROPERTY

    constructor(options: VisualConstructorOptions) {
        // constructor body
        // ...
    }

    public update(options: VisualUpdateOptions) {
        // update method body
        // ...
    }

    /**
     * Returns properties pane formatting model content hierarchies, properties and latest formatting values, Then populate properties pane.
     * This method is called once each time we open the properties pane or when the user edits any format property. 
     */
    public getFormattingModel(): powerbi.visuals.FormattingModel {
        return this.formattingSettingsService.buildFormattingModel(this.formattingSettings);
    }
}

更新视觉对象的构造函数：


export class Visual implements IVisual {
    // visual properties
    // ...
    private div: HTMLDivElement;

    constructor(options: VisualConstructorOptions) {
        console.log('Visual constructor', options);
        this.formattingSettingsService = new FormattingSettingsService();
        this.target = options.element;
        this.updateCount = 0;

        if (document) {
            const new_p: HTMLElement = document.createElement("p");
            new_p.appendChild(document.createTextNode("Update count:"));
            const new_em: HTMLElement = document.createElement("em");
            this.textNode = document.createTextNode(this.updateCount.toString());
            new_em.appendChild(this.textNode);
            new_p.appendChild(new_em);
            this.div = document.createElement("div"); // <== CREATE DIV ELEMENT
            this.target.appendChild(new_p);
        }
    }
}

要创建 button，请更新 update 视觉对象的方法：

export class Visual implements IVisual {
    // ...

    public update(options: VisualUpdateOptions) {
        this.formattingSettings = this.formattingSettingsService.populateFormattingSettingsModel(VisualFormattingSettingsModel, options.dataViews);
        console.log('Visual update', options);

        const dataView: DataView = options.dataViews[0];
        const categoricalDataView: DataViewCategorical = dataView.categorical;

        // don't create elements if no data
        if (!options.dataViews[0].categorical ||
            !options.dataViews[0].categorical.categories) {
            return
        }

        // to display current level of hierarchy
        if (typeof this.textNode !== undefined) {
            this.textNode.textContent = categoricalDataView.categories[categoricalDataView.categories.length - 1].source.displayName.toString();
        }

        // remove old elements
        // for better performance use D3js pattern:
        // https://d3js.org/#enter-exit
        while (this.div.firstChild) {
            this.div.removeChild(this.div.firstChild);
        }

        // create buttons for each category value
        categoricalDataView.categories[categoricalDataView.categories.length - 1].values.forEach( (category: powerbi.PrimitiveValue, index: number) => {
            let button = document.createElement("button");
            button.innerText = category.toString();

            this.div.appendChild(button);
        })

    }
    // ...

在 .\style\visual.less 中应用简单样式：

button {
    margin: 5px;
    min-width: 50px;
    min-height: 50px;
}

准备用于测试视觉对象的示例数据：

H1 H2 H3 VALUES
A A1 A11 1
A A1 A12 2
A A2 A21 3
A A2 A22 4
A A3 A31 5
A A3 A32 6
B B1 B11 7
B B1 B12 8
B B2 B21 9
B B2 B22 10
B B3 B31 11
B B3 B32 12

并在 Power BI Desktop 中创建层次结构：

屏幕截图展示了 Power BI Desktop，其中在关联菜单中选择了“新建层次结构”。

将所有类别列（H1、H2、H3）包括到新层次结构中：

屏幕截图展示了可以添加到新层次结构中的类别列。

完成这些步骤后，将获取以下视觉对象：

具有按钮的开发视觉对象

将上下文菜单添加到视觉对象元素

要向视觉对象上的按钮添加上下文菜单：

视觉对象中的上下文菜单

保存视觉对象属性中的 host 对象，并使用 Power BI 视觉对象 API 调用创建选择管理器的 createSelectionManager 方法以显示上下文菜单。

"use strict";

import "core-js/stable";
import "./../style/visual.less";
// default imports

import IVisualHost = powerbi.extensibility.visual.IVisualHost;
import ISelectionManager = powerbi.extensibility.ISelectionManager;
import ISelectionId = powerbi.visuals.ISelectionId;

export class Visual implements IVisual {
    // visual properties
    // ...
    private div: HTMLDivElement;
    private host: IVisualHost; // <== NEW PROPERTY
    private selectionManager: ISelectionManager; // <== NEW PROPERTY

    constructor(options: VisualConstructorOptions) {
        // constructor body
        // save the host in the visuals properties
        this.host = options.host;
        // create selection manager
        this.selectionManager = this.host.createSelectionManager();
        // ...
    }

    public update(options: VisualUpdateOptions) {
        // update method body
        // ...
    }

    // ...
}

将 forEach 函数回调的正文更改为：

    categoricalDataView.categories[categoricalDataView.categories.length - 1].values.forEach( (category: powerbi.PrimitiveValue, index: number) => {
        // create selectionID for each category value
        let selectionID: ISelectionId = this.host.createSelectionIdBuilder()
            .withCategory(categoricalDataView.categories[0], index)
            .createSelectionId();

        let button = document.createElement("button");
        button.innerText = category.toString();

        // add event listener to click event
        button.addEventListener("click", (event) => {
            // call select method in the selection manager
            this.selectionManager.select(selectionID);
        });

        button.addEventListener("contextmenu", (event) => {
            // call showContextMenu method to display context menu on the visual
            this.selectionManager.showContextMenu(selectionID, {
                x: event.clientX,
                y: event.clientY
            });
            event.preventDefault();
        });

        this.div.appendChild(button);
    });

将数据应用于视觉对象：

屏幕截图展示了层次结构，其中突出显示了“H2”。

在最后的步骤，你将获取带有选择和上下文菜单的视觉对象：

动画展示了从视觉对象的关联菜单中选择“向下钻取”和“向上钻取”。

添加矩阵数据视图映射的向下钻取支持

要使用矩阵数据视图映射测试视觉对象，首先要准备示例数据：

行 1 行 2 行 3 列 1 列 2 列 3 值
R1 R11 R111 C1 C11 C111 1
R1 R11 R112 C1 C11 C112 2
R1 R11 R113 C1 C11 C113 3
R1 R12 R121 C1 C12 C121 4
R1 R12 R122 C1 C12 C122 5
R1 R12 R123 C1 C12 C123 6
R1 R13 R131 C1 C13 C131 7
R1 R13 R132 C1 C13 C132 8
R1 R13 R133 C1 C13 C133 9
R2 R21 R211 C2 C21 C211 10
R2 R21 R212 C2 C21 C212 11
R2 R21 R213 C2 C21 C213 12
R2 R22 R221 C2 C22 C221 13
R2 R22 R222 C2 C22 C222 14
R2 R22 R223 C2 C22 C223 16
R2 R23 R231 C2 C23 C231 17
R2 R23 R232 C2 C23 C232 18
R2 R23 R233 C2 C23 C233 19

然后将以下数据视图映射应用于视觉对象：

{
    "dataRoles": [
        {
            "displayName": "Columns",
            "name": "columns",
            "kind": "Grouping"
        },
        {
            "displayName": "Rows",
            "name": "rows",
            "kind": "Grouping"
        },
        {
            "displayName": "Value",
            "name": "value",
            "kind": "Measure"
        }
    ],
    "drilldown": {
        "roles": [
            "columns",
            "rows"
        ]
    },
    "dataViewMappings": [
        {
            "matrix": {
                "columns": {
                    "for": {
                        "in": "columns"
                    }
                },
                "rows": {
                    "for": {
                        "in": "rows"
                    }
                },
                "values": {
                    "for": {
                        "in": "value"
                    }
                }
            }
        }
    ]
}

将数据应用于视觉对象：

屏幕截图展示了 MatrixHierarchy，其中选择了列和行层次结构及其成员。

导入所需接口以处理矩阵数据视图映射：

// ...
import DataViewMatrix = powerbi.DataViewMatrix;
import DataViewMatrixNode = powerbi.DataViewMatrixNode;
import DataViewHierarchyLevel = powerbi.DataViewHierarchyLevel;
// ...

为行和列元素的两个 div 创建两个属性：

export class Visual implements IVisual {
    // ...
    private rowsDiv: HTMLDivElement;
    private colsDiv: HTMLDivElement;
    // ...
    constructor(options: VisualConstructorOptions) {
        // constructor body
        // ...
        // Create div elements and append to main div of the visual
        this.rowsDiv = document.createElement("div");
        this.target.appendChild(this.rowsDiv);

        this.colsDiv = document.createElement("div");
        this.target.appendChild(this.colsDiv);
    }
    // ...
}

在呈现元素之前检查数据并显示层次结构的当前级别：

export class Visual implements IVisual {
    // ...
    constructor(options: VisualConstructorOptions) {
        // constructor body
    }

    public update(options: VisualUpdateOptions) {
        this.formattingSettings = this.formattingSettingsService.populateFormattingSettingsModel(VisualFormattingSettingsModel, options.dataViews);
        console.log('Visual update', options);

        const dataView: DataView = options.dataViews[0];
        const matrixDataView: DataViewMatrix = dataView.matrix;

        // if the visual doesn't receive the data no reason to continue rendering
        if (!matrixDataView ||
            !matrixDataView.columns ||
            !matrixDataView.rows ) {
            return
        }

        // to display current level of hierarchy
        if (typeof this.textNode !== undefined) {
            this.textNode.textContent = categoricalDataView.categories[categoricalDataView.categories.length - 1].source.displayName.toString();
        }
        // ...
    }
    // ...
}

创建用于遍历层次结构的函数 treeWalker：

export class Visual implements IVisual {
    // ...
    public update(options: VisualUpdateOptions) {
        // ...

        // if the visual doesn't receive the data no reason to continue rendering
        if (!matrixDataView ||
            !matrixDataView.columns ||
            !matrixDataView.rows ) {
            return
        }

        const treeWalker = (matrixNode: DataViewMatrixNode, index: number, levels: DataViewHierarchyLevel[], div: HTMLDivElement)  => {
            // ...
            if (matrixNode.children) {
                // ...
                // traversing child nodes
                matrixNode.children.forEach((node, index) => treeWalker(node, index, levels, childDiv));
            }
        }

        // traversing rows
        const rowRoot: DataViewMatrixNode = matrixDataView.rows.root;
        rowRoot.children.forEach((node, index) => treeWalker(node, index, matrixDataView.rows.levels, this.rowsDiv));

        // traversing columns
        const colRoot = matrixDataView.columns.root;
        colRoot.children.forEach((node, index) => treeWalker(node, index, matrixDataView.columns.levels, this.colsDiv));
    }
    // ...
}

为数据点生成选择项。

const treeWalker = (matrixNode: DataViewMatrixNode, index: number, levels: DataViewHierarchyLevel[], div: HTMLDivElement)  => {
    // generate selectionID for each node of matrix
    const selectionID: ISelectionID = this.host.createSelectionIdBuilder()
        .withMatrixNode(matrixNode, levels)
        .createSelectionId();
    // ...
    if (matrixNode.children) {
        // ...
        // traversing child nodes
        matrixNode.children.forEach((node, index) => treeWalker(node, index, levels, childDiv));
    }
}

为每个层次结构级别创建 div：

const treeWalker = (matrixNode: DataViewMatrixNode, index: number, levels: DataViewHierarchyLevel[], div: HTMLDivElement)  => {
    // generate selectionID for each node of matrix
    const selectionID: ISelectionID = this.host.createSelectionIdBuilder()
        .withMatrixNode(matrixNode, levels)
        .createSelectionId();
    // ...
    if (matrixNode.children) {
        // create div element for level
        const childDiv = document.createElement("div");
        // add to current div
        div.appendChild(childDiv);
        // create paragraph element to display next
        const p = document.createElement("p");
        // display level name on paragraph element
        const level = levels[matrixNode.level];
        p.innerText = level.sources[level.sources.length - 1].displayName;
        // add paragraph element to created child div
        childDiv.appendChild(p);
        // traversing child nodes
        matrixNode.children.forEach((node, index) => treeWalker(node, index, levels, childDiv));
    }
}

创建 buttons 以与视觉对象进行交互并显示用于矩阵数据点的上下文菜单：

const treeWalker = (matrixNode: DataViewMatrixNode, index: number, levels: DataViewHierarchyLevel[], div: HTMLDivElement)  => {
    // generate selectionID for each node of matrix
    const selectionID: ISelectionID = this.host.createSelectionIdBuilder()
        .withMatrixNode(matrixNode, levels)
        .createSelectionId();

    // create button element
    let button = document.createElement("button");
    // display node value/name of the button's text
    button.innerText = matrixNode.value.toString();

    // add event listener on click
    button.addEventListener("click", (event) => {
        // call select method in the selection manager
        this.selectionManager.select(selectionID);
    });

    // display context menu on click
    button.addEventListener("contextmenu", (event) => {
        // call showContextMenu method to display context menu on the visual
        this.selectionManager.showContextMenu(selectionID, {
            x: event.clientX,
            y: event.clientY
        });
        event.preventDefault();
    });

    div.appendChild(button);

    if (matrixNode.children) {
        // ...
    }
}

在再次呈现元素之前清除 div 元素：

public update(options: VisualUpdateOptions) {
    // ...
    const treeWalker = (matrixNode: DataViewMatrixNode, index: number, levels: DataViewHierarchyLevel[], div: HTMLDivElement)  => {
        // ...
    }

    // remove old elements
    // to better performance use D3js pattern:
    // https://d3js.org/#enter-exit
    while (this.rowsDiv.firstChild) {
        this.rowsDiv.removeChild(this.rowsDiv.firstChild);
    }
    // create label for row elements
    const prow = document.createElement("p");
    prow.innerText = "Rows";
    this.rowsDiv.appendChild(prow);

    while (this.colsDiv.firstChild) {
        this.colsDiv.removeChild(this.colsDiv.firstChild);
    }
    // create label for columns elements
    const pcol = document.createElement("p");
    pcol.innerText = "Columns";
    this.colsDiv.appendChild(pcol);

    // render elements for rows
    const rowRoot: DataViewMatrixNode = matrixDataView.rows.root;
    rowRoot.children.forEach((node, index) => treeWalker(node, index, matrixDataView.rows.levels, this.rowsDiv));

    // render elements for columns
    const colRoot = matrixDataView.columns.root;
    colRoot.children.forEach((node, index) => treeWalker(node, index, matrixDataView.columns.levels, this.colsDiv));
}

最后，你应该会得到一个具有上下文菜单的视觉对象：

动画展示了视觉对象的关联菜单，其中包含“向下钻取”或“向上钻取”选项。

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