小编Joe*_*Joe的帖子

我正在使用项目中令人敬畏的Knockout.js库,并且正在寻找一种在运行时构建UI部分的方法.

例如,我有一些由子模板组成的模板(简化如下).我想将视图模型传递给它们并渲染它们,然后能够从条件表单中追加(并删除)内容.

<!-- used with LineGraphModel -->
<script type="text/html" name="linegraph-template">
  <div id="LineGraph">
      <div data-bind="contextTemplate: { name: 'series-template', data: seriesChoices, context: { selected: series } }"></div>
      <div data-bind="contextTemplate: { name: 'xaxis-template', data: xAxisChoices, context: { selected: xaxis } }"></div>
      <div data-bind="contextTemplate: { name: 'daterange-template', data: dateRangeChoices, context: { selected: dateRange } }"></div>
      <div data-bind="template: { name: 'button-template', data: $data }"></div>
  </div>
</script>

<!-- used with PieChartModel -->
<script type="text/html" name="piechart-template">
  <div id="PieGraph">
    <div data-bind="contextTemplate: { name: 'series-template', data: seriesChoices, context: { …

在我的 Angular 应用程序中，我正在进行可选的 HTTP 调用来检查用户是否存在。根据这次通话的结果，我要么想再拨打一次电话，要么停止处理。如果不求助于.toPromise()，我如何等待在块中进行的调用if？

  onSomeEvent() {
    const contact: IContact = {
      ...this.userForm.value
    };

    let cancelProcessing = false;

    if (this.isNewUser()) {
      // *** This is optional
      this.userService.duplicateUserSearch(contact.email, contact.userName)
        .subscribe(result => {
          if (result.result !== '') {
            cancelProcessing = true;
          }
        });
    }

    // *** This statement is hit before the observable completes
    if (cancelProcessing) {
      return;
    }

    //  *** which means that this runs when it shouldn't
    this.userService.updateContact(contact)
      .subscribe(res => {
        this.activeModal.close(res);
      });
  }

我正在尝试Row在列表视图中添加一个内部，但出现错误

I/flutter (13858): ??? EXCEPTION CAUGHT BY RENDERING LIBRARY ??????????????????????????????????????????????????????????
I/flutter (13858): The following assertion was thrown during performLayout():
I/flutter (13858): BoxConstraints forces an infinite height.
I/flutter (13858): These invalid constraints were provided to RenderParagraph's layout() function by the following
I/flutter (13858): function, which probably computed the invalid constraints in question:
I/flutter (13858):   RenderFlex.performLayout (package:flutter/src/rendering/flex.dart:805:17)
I/flutter (13858): The offending constraints were:
I/flutter (13858):   BoxConstraints(w=72.0, h=Infinity)

按照针对该错误找到的指导，我尝试将我的 包装ListView在 中Expanded，但这只会导致Expanded widgets must be placed inside …

我有一个现有表Projects，我想向其中添加一个UserId列，其中UserId有一个外键。 Projects现在有一个名称列表，但我希望每个用户都可以管理自己的项目。我最初拥有“孤儿”是可以的，因为列表足够小，我可以手动清理它们。

我已经更新了模型以包含UserId和导航属性User（可能不相关，但是Entity这里是带有Id和的基类DateModified）

public class Project : Entity
{
    public string Name { get; set; }
    public Guid? UserId { get; set; } //tried this as nullable and non nullable
    public User User { get; set; }
}

我相关的映射文件是

public class ProjectMap : IEntityTypeConfiguration<Project>
{
    public void Configure(EntityTypeBuilder<Project> builder)
    {
        builder.Property(x => x.Name).IsRequired();
        builder.Property(x => x.UserId).IsRequired();

        builder.HasOne(x => x.User)
            .WithMany(x => x.Projects)
            .HasForeignKey(x …