我有一个类似于以下内容的json文件：
[ {
"level" : "1",
"name" : "TIER 1 - CORE FOUNDATIONS",
"required" : "13",
"completed" : "9",
"planned" : "0",
"subcategories" :
[ {
"level" : "2",
"id" : "39",
"name" : "Critical Reading and Writing",
"required" : "6",
"completed" : "3",
"planned" : "0",
"subcategories" : [],
"courses" : [
{"course_number" : "ENGL-1301", "course_name" : "English", "credits" : "3.0", "grade" : "A"}
]
},
{
"level" : "2",
"id" : "40",
"name" : "Speaking and Listening",
"required" : "3",
"completed" : "3",
"planned" : "0",
"subcategories" : [],
"courses" : [
{"course_number" : "SPCH-1311", "course_name" : "SPCH", "credits" : "3.0", "grade" : "A"}
]
},
{
"level" : "2",
"id" : "41",
"name" : "Quantitative Reasoning",
"required" : "3",
"completed" : "0",
"planned" : "0",
"subcategories" : [],
"courses" : []
},
{
"level" : "2",
"id" : "42",
"name" : "Wellness and The Human Experience",
"required" : "3",
"completed" : "0",
"planned" : "0",
"subcategories" : [],
"courses" : []
}
],
"courses" : []
},
{
"level" : "1",
"name" : "TIER 2 - CORE DOMAINS",
"required" : "26",
"completed" : "10",
"planned" : "0",
"subcategories" :
[ {
"level" : "2",
"id" : "27",
"name" : "Qualitative Reasoning, Literacy and Research",
"required" : "3",
"completed" : "3",
"planned" : "0",
"subcategories" : [],
"courses" : [
{"course_number" : "ENGL-1302", "course_name" : "English", "credits" : "3.0", "grade" : "A"}
]
},
{
"level" : "2",
"id" : "32",
"name" : "Self and Society",
"required" : "9",
"completed" : "3",
"planned" : "0",
"subcategories" : [
{
"level" : "3",
"id" : "35",
"name" : "CB080",
"required" : "3",
"completed" : "3",
"planned" : "0",
"subcategories" : [],
"courses" : [
{"course_number" : "PSYC-2301", "course_name" : "General Psychology", "credits" : "3.0", "grade" : "C"}
]
},
{
"level" : "3",
"id" : "34",
"name" : "CB070",
"required" : "9",
"completed" : "3",
"planned" : "3",
"subcategories" : [],
"courses" : [
{"course_number" : "GOVT-2305", "course_name" : "Federal Government", "credits" : "3.0", "grade" : "A"}
]
},
{
"level" : "3",
"id" : "33",
"name" : "CB060",
"required" : "9",
"completed" : "3",
"planned" : "0",
"subcategories" : [],
"courses" : []
},
],
"courses" : []
},
{
"level" : "2",
"id" : "29",
"name" : "Humanity, Creativity and the Aesthetic Experience",
"required" : "6",
"completed" : "3",
"planned" : "0",
"subcategories" : [
{
"level" : "3",
"id" : "34",
"name" : "CB050",
"required" : "3",
"completed" : "3",
"planned" : "0",
"subcategories" : [],
"courses" : [
{"course_number" : "ARTS-1301", "course_name" : "Art Apprec", "credits" : "3.0", "grade" : "A"}
]
},
{
"level" : "3",
"id" : "34",
"name" : "CB040",
"required" : "3",
"completed" : "0",
"planned" : "0",
"subcategories" : [],
"courses" : [
{"course_number" : "ENGL-2328", "course_name" : "American Lit", "credits" : "3.0", "grade" : "A"}
]
},
],
"courses" : []
},
{
"level" : "2",
"id" : "31",
"name" : "Scientific Discovery and Sustainability",
"required" : "8",
"completed" : "4",
"planned" : "0",
"subcategories" : [],
"courses" : [
{"course_number" : "BIOL-1406", "course_name" : "Biology", "credits" : "4.0", "grade" : "B"}
]
}
],
"courses" : []
},
{
"level" : "1",
"name" : "TIER 3 - INTEGRATIVE LEARNING",
"required" : "3",
"completed" : "0",
"planned" : "0",
"subcategories" : [
{
"level" : "2",
"id" : "37",
"name" : "",
"required" : "3",
"completed" : "0",
"planned" : "0",
"subcategories" : [],
"courses" : []
}
],
"courses" : []
},
{
"level" : "1",
"name" : "AS.SCIENCE GENERAL ELECTIVES",
"required" : "18",
"completed" : "13",
"planned" : "0",
"subcategories" :
[ {
"level" : "2",
"id" : "25",
"name" : "",
"required" : "18",
"completed" : "13",
"planned" : "0",
"subcategories" : [],
"courses" : [
{"course_number" : "ECON-2302", "course_name" : "Economics", "credits" : "3.0", "grade" : "A"},
{"course_number" : "COSC-1300", "course_name" : "COSC", "credits" : "3.0", "grade" : "B"},
{"course_number" : "HDEV-1300", "course_name" : "HDEV", "credits" : "3.0", "grade" : "A"},
{"course_number" : "CHEM-1405", "course_name" : "Chemistry", "credits" : "4.0", "grade" : "C"},
{"course_number" : "BIOL-2401", "course_name" : "Biology", "credits" : "--", "grade" : "--"}
]
}
],
"courses" : []
}
]
在这个json文件中，它有不规则性，即。 level 2中的某些子类别包含level 3个元素，而其他子类别包含courses而不是level 3。
如何以角度编写 if 语句，以便在2级子类别下存在3级，然后显示3级课程。否则，2级课程？所以我想知道是否有办法编写ifexists（）语句
答案 0 :(得分：2)
查看ng-if上的文档。
答案 1 :(得分：2)
你可以对子类别使用ng-repeat，如果它是空数组，它将不会显示该子类别。
<div ng-repeat="item in json">
<h1>{{ item.level }}</h1>
<ul ng-show="item.courses.length">
<li ng-repeat="course in item.courses">{{course.course_number}}</li>
</ul>
<div ng-repeat="sub in item.subcategories">
<h2>{{ sub.level }}</h2>
<ul ng-show="sub.courses.length">
<li ng-repeat="course in sub.courses">{{course.course_number}}</li>
</ul>
<div ng-repeat="sub_sub in sub.subcategories">
<h3>{{ sub_sub.level }}</h3>
<ul ng-show="sub_sub.courses.length">
<li ng-repeat="course in sub_sub.courses">{{course.course_number}}</li>
</ul>
</div>
</div>
</div>