Question

我正在考虑使用react-select作为城市选择器的选择器，用户可以选择1个或多个城市来过滤某些数据。以下是我在页面中呈现的屏幕截图：

城市列表可能很大，如果一次选择大号，我不希望选择器在其蓝色容器之外增长。以下是我现在模拟的情况：

我不是那个狂热的粉丝！我能想到的另一个选择是渲染“选择4个城市”而不是整个列表。这将在页面上具有可预测的大小。

如何使用react-select完成此操作？

Answer 1

渲染“已选择N个项目”

这可以通过valueRenderer和className道具以及最少量的CSS来实现。

这里我正常显示前三个选项，然后选择了4个以上项目时选择“N个项目”。除了“选择了N个项目”之外，显示删除选择图标（×）是没有意义的，所以我也删除了（使用CSS）。

class App extends React.Component {
  state = {
    value: [],
  }
  className = () => {
    const baseClassName = 'my-react-select';
    
    if (this.state.value.length <= 3) {
      return baseClassName;
    }
    
    return `${baseClassName} ${baseClassName}--compact`;
  }
  handleChange = (value) => {
    this.setState({ value });
  }
  renderValue = (option) => {
    // The first three selections are rendered normally
    if (this.state.value.length <= 3) {
      return option.label;
    }

    // With more selections, render "N items selected".
    // Other than the first one are hidden in CSS.
    return <span>{this.state.value.length} items selected</span>;
  }
  render() {
    return (
      <Select
        className={this.className()}
        multi
        onChange={this.handleChange}
        options={[
          { value: 'zero',  label: 'Zero' },
          { value: 'one',   label: 'One' },
          { value: 'two',   label: 'Two' },
          { value: 'three', label: 'Three' },
          { value: 'four',  label: 'Four' },
          { value: 'five',  label: 'Five' },
          { value: 'six',   label: 'Six' },
          { value: 'seven', label: 'Seven' },
          { value: 'eight', label: 'Eight' },
          { value: 'nine',  label: 'Nine' },
        ]}
        value={this.state.value}
        valueRenderer={this.renderValue}
      />
    );
  }
}

ReactDOM.render(<App />, document.getElementById('root'));

.my-react-select {
  /* Custom styles */
}

.my-react-select--compact .Select-value:first-child {
  font-style: italic;
}
.my-react-select--compact .Select-value:first-child .Select-value-icon,
.my-react-select--compact .Select-value:nth-child(n+2) {
  display: none;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react-dom.min.js"></script>

<script src="https://unpkg.com/prop-types@15.5.10/prop-types.js"></script>
<script src="https://unpkg.com/classnames@2.2.5/index.js"></script>
<script src="https://unpkg.com/react-input-autosize@2.0.0/dist/react-input-autosize.js"></script>
<script src="https://unpkg.com/react-select/dist/react-select.js"></script>

<link rel="stylesheet" href="https://unpkg.com/react-select/dist/react-select.css">

<div id="root"></div>

替代方法

查看截图，看起来有空间可以显示最多四个选项而不会使选择器溢出。选择4个以上的城市时，可以正常显示前3个选项，然后再显示“+ N更多”。像这样：

城市A
城市A，城市B
城市A，城市B，C城
城市A，城市B，城市C，+ 1更多
城市A，城市B，城市C，+ 2更多
城市A，城市B，城市C，+ 3更多
等

从用户体验的角度来看，我认为通常显示前3个左右的选项是件好事。如果在选择第四个城市后，每个选项突然隐藏在“选择的4个项目”后面，这会让人感到困惑。

此解决方案与第一个解决方案非常相似。 className道具现在只是一个字符串。 renderValue方法和CSS选择器有点不同。

class App extends React.Component {
  state = {
    value: [],
  }
  handleChange = (value) => {
    this.setState({ value });
  }
  renderValue = (option) => {
    // The first three values are rendered normally
    if (this.state.value.indexOf(option) < 3) {
      return option.label;
    }

    // Render the rest as "+ N more". 
    // Other than the first one are hidden in CSS.
    return <span>+ {this.state.value.length - 3} more</span>;
  }
  render() {
    return (
      <Select
        className='my-react-select'
        multi
        onChange={this.handleChange}
        options={[
          { value: 'zero',  label: 'Zero' },
          { value: 'one',   label: 'One' },
          { value: 'two',   label: 'Two' },
          { value: 'three', label: 'Three' },
          { value: 'four',  label: 'Four' },
          { value: 'five',  label: 'Five' },
          { value: 'six',   label: 'Six' },
          { value: 'seven', label: 'Seven' },
          { value: 'eight', label: 'Eight' },
          { value: 'nine',  label: 'Nine' },
        ]}
        value={this.state.value}
        valueRenderer={this.renderValue}
      />
    );
  }
}

ReactDOM.render(<App />, document.getElementById('root'));

/* If you change the amount of how many selections are shown normally,
 * be sure to adjust these selectors accordingly. */
.my-react-select .Select-value:nth-child(4) {
  font-style: italic;
}
.my-react-select .Select-value:nth-child(4) .Select-value-icon,
.my-react-select .Select-value:nth-child(n+5) {
  display: none;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react-dom.min.js"></script>

<script src="https://unpkg.com/prop-types@15.5.10/prop-types.js"></script>
<script src="https://unpkg.com/classnames@2.2.5/index.js"></script>
<script src="https://unpkg.com/react-input-autosize@2.0.0/dist/react-input-autosize.js"></script>
<script src="https://unpkg.com/react-select/dist/react-select.js"></script>

<link rel="stylesheet" href="https://unpkg.com/react-select/dist/react-select.css">

<div id="root"></div>

这是显示选择的另一种方法：

城市A
城市A，城市B
城市A，城市B，C城
城市A，城市B，城市C，城市D
城市A，城市B，城市C，+ 2更多
城市A，城市B，城市C，+ 3更多
等

renderValue方法再次有点不同。 CSS选择器现在有点丑陋和复杂，但它们都有效。

class App extends React.Component {
  state = {
    value: [],
  }
  handleChange = (value) => {
    this.setState({ value });
  }
  renderValue = (option) => {
    // The first four values are rendered normally
    if (this.state.value.length <= 4) {
      return option.label;
    }

    // The first 3 values are rendered normally when
    // more than 4 selections have been made
    if (this.state.value.indexOf(option) < 3) {
      return option.label;
    }

    // Render the rest as "+ N more".
    // Other than the first one are hidden in CSS.
    return <span>+ {this.state.value.length - 3} more</span>;
  }
  render() {
    return (
      <Select
        className='my-react-select'
        multi
        onChange={this.handleChange}
        options={[
          { value: 'zero',  label: 'Zero' },
          { value: 'one',   label: 'One' },
          { value: 'two',   label: 'Two' },
          { value: 'three', label: 'Three' },
          { value: 'four',  label: 'Four' },
          { value: 'five',  label: 'Five' },
          { value: 'six',   label: 'Six' },
          { value: 'seven', label: 'Seven' },
          { value: 'eight', label: 'Eight' },
          { value: 'nine',  label: 'Nine' },
        ]}
        value={this.state.value}
        valueRenderer={this.renderValue}
      />
    );
  }
}

ReactDOM.render(<App />, document.getElementById('root'));

/* If you change the amount of how many selections are shown normally,
 * be sure to adjust these selectors accordingly. */
.my-react-select .Select-value:nth-child(4):not(:nth-last-child(2)) {
  font-style: italic;
}
.my-react-select .Select-value:nth-child(4):not(:nth-last-child(2)) .Select-value-icon,
.my-react-select .Select-value:nth-child(n+5) {
  display: none;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react-dom.min.js"></script>

<script src="https://unpkg.com/prop-types@15.5.10/prop-types.js"></script>
<script src="https://unpkg.com/classnames@2.2.5/index.js"></script>
<script src="https://unpkg.com/react-input-autosize@2.0.0/dist/react-input-autosize.js"></script>
<script src="https://unpkg.com/react-select/dist/react-select.js"></script>

<link rel="stylesheet" href="https://unpkg.com/react-select/dist/react-select.css">

<div id="root"></div>

Answer 2

这是我使用react-select 3.x更新的答案。不涉及CSS。我用自定义的多值消息覆盖了ValueContainer的子级。在此之前，您需要导入以下内容

import React from "react";
import Select, { components } from "react-select";

变化1

显示一般消息：n items selected

<Select
  ...
  isMulti
  closeMenuOnSelect={false}
  hideSelectedOptions={false}
  components={{
    ValueContainer: ({ children, ...props }) => {
      let [values, input] = children;

      if (Array.isArray(values)) {
        const plural = values.length === 1 ? "" : "s";
        values = `${values.length} item${plural} selected`;
      }

      return (
        <components.ValueContainer {...props}>
          {values}
          {input}
        </components.ValueContainer>
      );
    }
  }}
/>

结果

变化2

在显示一般消息之前，显示一些命名项：item1, item2, item3 and n others selected

<Select
  ...
  isMulti
  closeMenuOnSelect={false}
  hideSelectedOptions={false}
  components={{
    ValueContainer: ({ children, ...props }) => {
      let [values, input] = children;

      if (Array.isArray(values)) {
        const val = (i: number) => values[i].props.children;
        const { length } = values;

        // I know you can use loops here to create the message
        // but this keeps the logic simple and more maintainable in the long run.
        switch (length) {
          case 1:
            values = `${val(0)} selected`;
            break;
          case 2:
            values = `${val(0)} and ${val(1)} selected`;
            break;
          case 3:
            values = `${val(0)}, ${val(1)} and ${val(2)} selected`;
            break;
          default:
            const plural = values.length === 3 + 1 ? "" : "s";
            const otherCount = length - 3;
            values = `${val(0)}, ${val(1)}, ${val(
              2
            )} and ${otherCount} other${plural} selected`;
            break;
        }
      }

      return (
        <components.ValueContainer {...props}>
          {values}
          {input}
        </components.ValueContainer>
      );
    }
  }}
/>

实时演示

Answer 3

在我看来，我会覆盖css以使大小固定。这是css的问题。我将检查元素并进行更改。

让我们看看上面的例子。这是你需要调整的CSS：

.Select-control {
background-color: #fff;
border-color: #d9d9d9 #ccc #b3b3b3;
border-radius: 4px;
border: 1px solid #ccc;
color: #333;
cursor: default;
display: table;
border-spacing: 0;
border-collapse: separate;
height: 36px;
outline: none;
overflow: hidden;
position: relative;
width: 100%;

}

现在移除display: table;并添加适当的高度。

如何使用react-select

3 个答案:

渲染“已选择N个项目”

替代方法

变化1

结果

变化2

实时演示