Php – How to access a key from multidimensional array in smarty

multidimensional-arrayPHPsmarty

I've got the following multidimensional array named $cs_map_data in PHP file and I've assigned it to the smarty template:

Now I want to access the value of key [cs_map_id] and [subject_name]of every element in smarty template. I tried using foreach but couldn't get the value from key [cs_map_id] and [subject_name].
Can anyone help me on how should I access thee value of key [cs_map_id] and [subject_name] in foreach loop in smarty.
Code written by me in smarty template is as follows :

<table>                         
              <tr>
                 {assign var='i' value=0}
                 {if $cs_map_data}
                 {foreach from=$cs_map_data item="map_data"}
                 {if $i%4 == 0}</tr><tr>{/if}
                 <td align="left" valign="top" width="150">

                  <input type="checkbox" name="cs_map_id[]" id="{$map_data.cs_map_id}" value="{$map_data.cs_map_id}"  onChange="get_test_by_category('{$map_data.cs_map_id}'); return false;" />
                 {$map_data.subject_name}
                 </td>
                 {assign var='i' value=$i+1}
                 {/foreach}
                 {else}
                        <td>
                            <i>No Subject is assigned to the class.</i>
                    </td>
                 {/if}
                </tr>
               </table>

Can any one help me on how to use both the key's values in forech in smarty template?
Thanks in advance.

Best Answer

This will work in Smarty 2 and 3. The {foreach} changed a lot between versions, but {section} works the same.

{section name=map loop=$cs_map_data}
    <tr>
         <td>{$cs_map_data[map].class_name}</td> //this is the format to access your data from the array
    {section name=subject loop=$cs_map_data[map].class_subjects}
          <td>
                {$cs_map_data[map].class_subjects[subject].subject_name} //this is how to access the entries of your 'inner' array
          </td>
    {/section} //end your nested section
    </tr>
{/section} //end your outer section

This SHOULD work to loop through your array...

The smarty manual for sections: http://www.smarty.net/docsv2/en/language.function.section.tpl

Good luck!

Deleting a single array element

If you want to delete just one array element you can use unset() or alternatively \array_splice().

If you know the value and don’t know the key to delete the element you can use \array_search() to get the key. This only works if the element does not occur more than once, since \array_search returns the first hit only.

`unset()`

Note that when you use unset() the array keys won’t change. If you want to reindex the keys you can use \array_values() after unset(), which will convert all keys to numerically enumerated keys starting from 0.

Code:

$array = [0 => "a", 1 => "b", 2 => "c"];
unset($array[1]);
          // ↑ Key which you want to delete

Output:

[
    [0] => a
    [2] => c
]

`\array_splice()` method

If you use \array_splice() the keys will automatically be reindexed, but the associative keys won’t change — as opposed to \array_values(), which will convert all keys to numerical keys.

\array_splice() needs the offset, not the key, as the second parameter.

Code:

$array = [0 => "a", 1 => "b", 2 => "c"];
\array_splice($array, 1, 1);
                   // ↑ Offset which you want to delete

Output:

[
    [0] => a
    [1] => c
]

array_splice(), same as unset(), take the array by reference. You don’t assign the return values of those functions back to the array.

Deleting multiple array elements

If you want to delete multiple array elements and don’t want to call unset() or \array_splice() multiple times you can use the functions \array_diff() or \array_diff_key() depending on whether you know the values or the keys of the elements which you want to delete.

`\array_diff()` method

If you know the values of the array elements which you want to delete, then you can use \array_diff(). As before with unset() it won’t change the keys of the array.

Code:

$array = [0 => "a", 1 => "b", 2 => "c", 3 => "c"];
$array = \array_diff($array, ["a", "c"]);
                          // └────────┘
                          // Array values which you want to delete

Output:

[
    [1] => b
]

`\array_diff_key()` method

If you know the keys of the elements which you want to delete, then you want to use \array_diff_key(). You have to make sure you pass the keys as keys in the second parameter and not as values. Keys won’t reindex.

Code:

$array = [0 => "a", 1 => "b", 2 => "c"];
$array = \array_diff_key($array, [0 => "xy", "2" => "xy"]);
                               // ↑           ↑
                               // Array keys which you want to delete

Output:

[
    [1] => b
]

If you want to use unset() or \array_splice() to delete multiple elements with the same value you can use \array_keys() to get all the keys for a specific value and then delete all elements.

C# – What are the differences between a multidimensional array and an array of arrays in C#

Array of arrays (jagged arrays) are faster than multi-dimensional arrays and can be used more effectively. Multidimensional arrays have nicer syntax.

If you write some simple code using jagged and multidimensional arrays and then inspect the compiled assembly with an IL disassembler you will see that the storage and retrieval from jagged (or single dimensional) arrays are simple IL instructions while the same operations for multidimensional arrays are method invocations which are always slower.

Consider the following methods:

static void SetElementAt(int[][] array, int i, int j, int value)
{
    array[i][j] = value;
}

static void SetElementAt(int[,] array, int i, int j, int value)
{
    array[i, j] = value;
}

Their IL will be the following:

.method private hidebysig static void  SetElementAt(int32[][] 'array',
                                                    int32 i,
                                                    int32 j,
                                                    int32 'value') cil managed
{
  // Code size       7 (0x7)
  .maxstack  8
  IL_0000:  ldarg.0
  IL_0001:  ldarg.1
  IL_0002:  ldelem.ref
  IL_0003:  ldarg.2
  IL_0004:  ldarg.3
  IL_0005:  stelem.i4
  IL_0006:  ret
} // end of method Program::SetElementAt

.method private hidebysig static void  SetElementAt(int32[0...,0...] 'array',
                                                    int32 i,
                                                    int32 j,
                                                    int32 'value') cil managed
{
  // Code size       10 (0xa)
  .maxstack  8
  IL_0000:  ldarg.0
  IL_0001:  ldarg.1
  IL_0002:  ldarg.2
  IL_0003:  ldarg.3
  IL_0004:  call       instance void int32[0...,0...]::Set(int32,
                                                           int32,
                                                           int32)
  IL_0009:  ret
} // end of method Program::SetElementAt

When using jagged arrays you can easily perform such operations as row swap and row resize. Maybe in some cases usage of multidimensional arrays will be more safe, but even Microsoft FxCop tells that jagged arrays should be used instead of multidimensional when you use it to analyse your projects.

Best Answer

Related Solutions

Php – Deleting an element from an array in PHP

Deleting a single array element

unset()

\array_splice() method

Deleting multiple array elements

\array_diff() method

\array_diff_key() method

C# – What are the differences between a multidimensional array and an array of arrays in C#

Related Topic

`unset()`

`\array_splice()` method

`\array_diff()` method

`\array_diff_key()` method