Angular 6 和 PHP:即使在使用附加到 httpParams 时，HttpClient 也不会将数组发送到服务器

您的 PHP 脚本正在调用 json_encode()，它会生成一个 JSON细绳.如果您的意图是将 JSON 转换为数组，请执行以下操作json_decode().但是，在任何事情之前，请确保无论您是传入 json_decode() 还不是数组.

I need to send an array of data using HttpClient of Angular 6 to PHP server.

I have some drop down list where I chose from and push into an array:

arrayOfLegalProtection=[];
addSit(){
    let l_id = '';
    let p_id = '';
    let s_id = '';
    let add_date = '';
    l_id = this.formGroup.controls['l_id'].value;

    p_id = this.formGroup.controls['p_id'].value;
    s_id = this.formGroup.controls['s_id'].value;
    add_date = this.formGroup.controls['add_date'].value;
    this.showSubHeader++;
    this.arrayOfLegalProtection.push({lId: l_id, 
      pId: p_id,
      sId: s_id, 
      addDate: add_date})
    console.log(this.arrayOfLegalProtection);
}

The console result is showing me the correct pushed values:

[{"lId":"1","prId":"1","sId":"2","addDate":"2018-09-14"},

{"lId":"","pId":"1","sId":"5","addDate":"2018-09-14"},

{"lId":"","pId":"2","sId":"","addDate":"2018-09-20"}]

Now, I need to add this array to httpclient post method and send it to the server, but as said in the discussion of this post, arrays cannot be sent through angular's HttpClient library.

We need to use append, or JSON.stringify() or .append().

I posted a question after using the method of JSON.stringify() and as you can see there was errors. And even the echo count($array) is always 1 even if the multidimensional array contains 0 or N rows of data.

So I switched, for the other method using the .append():

saveUnitData(unit_type, 
    location_type_id, user_id, number_of_hh, unit_status, add_date, arrayOfActualities)
  { 
    console.log(user_id);
    let httpParam = new HttpParams().set('unit_type', unit_type)
                                      .set('location_type_id', location_type_id)
                                      .set('user_id', user_id)
                                      .set('number_of_hh', number_of_hh)
                                      .set('unit_status',unit_status)
                                      .set('add_date', add_date);
    Object.keys(arrayOfActualities).forEach(key=>{
      httpParam = httpParam.append('arrayOfActualities', arrayOfActualities);
    })
                                      //.set('arrayOfActualities', arrayOfActualities);
    let headerOptions = new HttpHeaders();
    headerOptions.append('Content-Type', 'application/x-www-form-urlencoded; charset=UTF-8');
    console.log('h'+arrayOfActualities);
    return this.http.post(this.globalVar.UnitSavedataUrl, httpParam, {headers: headerOptions});
  }

Using this code:

Object.keys(arrayOfActualities).forEach(key=>{
          httpParam = httpParam.append('arrayOfActualities', arrayOfActualities);

I tried to convert an object into array using append so it can be sent through the httpClient service.

At the header of the request, we can see the ordinary data sent, but the array is being repeated hundreds and hundreds of times.

And the response from server is always:

C:\wamp64\www\dev\UnitSaveData.php:23:string '[{"legalId":"","protectionId":"","situationId":"","addDate":"2018-09-14"},{"legalId":"","protectionId":"","situationId":"","addDate":"2018-09-14"}]' (length=147)

But nothing was added to the database.

Please note that the PHP script is the same from the previous unanswered post

I found the solution.

Yes, HttpClient() do accept an array as HttpParams().

For the Angular script, I was doing the following:

let httpParam = new HttpParams().set('unit_type', unit_type)
   .set('location_type_id', location_type_id)
   .set('user_id', user_id)
   .set('number_of_hh', number_of_hh)
   .set('unit_status',unit_status)
   .set('add_date', add_date)
   .set('arrayOfActualities', arrayOfActualities); 

As the HttpParams() documentation mentioned, .set() take the value as a string which confused the server side script even when using json_encode().

So the solution was to append to arrayOfActualities the array:

let httpParam = new HttpParams().set('unit_type', unit_type)
    .set('location_type_id', location_type_id)
    .set('user_id', user_id)
    .set('number_of_hh', number_of_hh)
    .set('unit_status',unit_status)
    .set('add_date', add_date)
    .set('arrayOfActualities', arrayOfActualities);

httpParam.append('arrayOfActualities', JSON.stringify(arrayOfActualities));

At the PHP side, I need to use json_decode($arr, true), in order to let the server script iterate over an array, as iterating over a json array was making problem for me as it wasn't able to read the field titles because of double quotes:

$arr = json_decode($arrayOfActualities, true);
if(count($arr)>0)
  {
     foreach($arr as $array)
     {

     }
  }

...

As, like @B.Fleming said:

Your PHP script is calling json_encode(), which produces a JSON string. If your intent is to transform JSON into an array, do json_decode(). Before anything, though, ensure that whatever you're passing into json_decode() is not already an array.

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