Angular2从JSON数组中删除重复项

时间:2016-07-21 10:16:06

标签: arrays angularjs filter angular ngfor

当我将应用程序移动到Angular2时,我的JSON数组中的过滤器出现问题。在Angular 1.x中更容易。我在过滤器中使用了'unique',这将删除所有重复项。

应用程式:

{"app":"database_1",
 "host":"my_host1",
 "ip":"00.000.00.000"
},
{"app":"database_1",
 "host":"my_host1",
 "ip":"00.000.00.000"
},
{"app":"database_2",
 "host":"my_host2",
 "ip":"00.000.00.000"
},
{"app":"database_2",
 "host":"my_host2",
 "ip":"00.000.00.000"
}

部分HTML代码:

    <div *ngFor='#appsUnique of apps '>
        <div class="row dashboard-row">
            <div class="col-md-2">
               <h4>{{appsUnique.app }}</h4>
            </div>
        </div>
    </div>

结果是:

database_1
database_1
database_2
database_2

我想得到结果:

database_1
database_2

如何从数组中删除重复项?

6 个答案:

答案 0 :(得分:10)

Mybe它可以帮助你

#!/bin/bash

# Vars
TODAY=$(date +%d%m%y)
BDIR=/backup/
FLOG="/var/log/mydb_backup.log"

# Backing up the db
su -c "pg_dump --format=c --file=${BDIR}mydb_db_backup.${TODAY} mydb" postgres
if [ $? -eq 0 ]; then
  LOG="mydb DB of ${TODAY} backed up!"
else
  LOG="Problem to back up mydb DB of ${TODAY}"
fi


# Delete db backup older than 180+ days
find ${BDIR} -type f -mtime +180 -delete
if [ $? -eq 0 ]; then
  LOG+=" - Old DB backup deleted"
else
  LOG+=" - No Old DB backup to delete"
fi

# Writing result
echo ${LOG} >> ${FLOG}

答案 1 :(得分:6)

我有解决这个问题的方法:)

Array.from(new Set([{"app":"database_1",
 "host":"my_host1",
 "ip":"00.000.00.000"
},
{"app":"database_1",
 "host":"my_host1",
 "ip":"00.000.00.000"
},
{"app":"database_2",
 "host":"my_host2",
 "ip":"00.000.00.000"
},
{"app":"database_2",
 "host":"my_host2",
 "ip":"00.000.00.000"
}].map((itemInArray) => itemInArray.app)))

More about Array.from & Set

感谢大家的帮助:)

答案 2 :(得分:3)

您可以使用以下方法:

names = ["Mike","Matt","Nancy","Adam","Jenny","Nancy","Carl"];

ngOnInit() {
    let filteredNames=this.remove_duplicates(this.names);
    console.log(filteredNames);
    console.log(this.names);
}
remove_duplicates(arr) {
    let obj = {};
    for (let i = 0; i < arr.length; i++) {
        obj[arr[i]] = true;
    }
    arr = [];
    for (let key in obj) {
        arr.push(key);
    }
    return arr;
}

希望这有帮助。

答案 3 :(得分:2)

你也可以使用Observable方法,这很简单。

let filteredData = [];
let arrayData = [{
  "app": "database_1",
  "host": "my_host1",
  "ip": "00.000.00.000"
},
{
  "app": "database_1",
  "host": "my_host1",
  "ip": "00.000.00.000"
},
{
  "app": "database_2",
  "host": "my_host2",
  "ip": "00.000.00.000"
},
{
  "app": "database_2",
  "host": "my_host2",
  "ip": "00.000.00.000"
}];

Observable.merge(arrayData)
  .distinct((x) => x.app)
  .subscribe(y => {
    filteredData.push(y)
    console.log(filteredData)
  });

答案 4 :(得分:1)

不是循环遍历普通的json数组,而是可以在相应的typescript类中创建另一个数组,并根据需要更改它。在您的HTML中,您可以拥有以下

HTML

 <div *ngFor='let appsUnique of filteredApps'>
    <div class="row dashboard-row">
        <div class="col-md-2">
           <h4>{{appsUnique.app }}</h4>
        </div>
    </div>
</div>

接下来,您需要在相应的typescript类中使用此filteredApps数组。

打字稿

 let filteredApps = [];

然后在函数中,您可以创建filterApps,例如在onInit方法中。

onInit()
{
    filteredApps = // filter logic
}

答案 5 :(得分:1)

您需要trackBy

尝试:

*ngFor="#appsUnique of posts;trackBy:appsUnique?.app"

希望它有所帮助。