Question 269291 in PHP Question posted in
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How to cast String to Int using PHP with PostgreSQL

I am working with an api written in php, that is getting data from a postgres database. one of the fields of data is however getting returned by the query as lexicographic sorted. I thus want to try casting it as integer. If that is wrong, please suggest me alternative approaches. Here’s the relevant code snippet

case( 'location_group' ):
    $filter_label_column = 'location_group_' . $pk_location_group_type . '_name';

    if( !is_missing_or_empty( $request['params'], 'filter_label' ) )
    {
          $filter_label_column = 'location_group_' . $pk_location_group_type . '_' . $request['params']['filter_label'];
    }

    $query->select( [ $filter . "_$pk_location_group_type", 'pk' ], [ $filter_label_column, 'label' ] )
          ->group( $filter . "_$pk_location_group_type", $filter_label_column )
          ->order( 'label', 'asc' );
    break;

Tried casting in multiple ways, and as a result no data gets returned for the label, tried following (also tried replacing SIGNED with INTEGER):

case 'location_group':
    $filter_label_column = 'location_group_' . $pk_location_group_type . '_name';

    if (!is_missing_or_empty($request['params'], 'filter_label')) {
        $filter_label_column = 'location_group_' . $pk_location_group_type . '_' . $request['params']['filter_label'];
    }

    $query->select([$filter . "_$pk_location_group_type", 'pk'], ["CAST($filter_label_column AS SIGNED)", 'label'])
          ->group($filter . "_$pk_location_group_type", "CAST($filter_label_column AS SIGNED)")
          ->order('label', 'asc');
    break;
Tags:

2

Answers


  1. 0

    Casting the field as an integer using CAST should work in most cases when you want to treat a lexicographically sorted field as an integer. However, if it’s not returning the expected results, here are a few things you can try:

    1. Use ::integer for Postgres casting:

      Instead of using CAST, you can use ::integer for casting in Postgres. Try the following code:

      $query->select([$filter . "_$pk_location_group_type", 'pk'], ["$filter_label_column::integer", 'label'])
    ->group($filter . "_$pk_location_group_type", "$filter_label_column::integer")
    ->order('label', 'asc');

    2. Check for invalid data:

      Verify that the data in the column you are trying to cast to an integer is valid and can be cast to an integer. If there are non-numeric characters or invalid data in the column, casting may not work as expected.

    3. Debug the SQL query:

      You can print or log the generated SQL query to see if the casting is done correctly. This can help you identify any issues with the SQL statement itself. For example:

      $sql = $query->toSql();
echo $sql;

    4. Check the actual data in the database:

      Make sure that the data in the database is what you expect. Sometimes the issue may be related to data quality or how it’s stored in the database.

    5. Consider using CASE for conditional casting:

      If the data in the column is not always numeric, you can use a CASE statement to conditionally cast it as an integer when appropriate. For example:

      $query->select([$filter . "_$pk_location_group_type", 'pk'], [
    DB::raw("CASE WHEN $filter_label_column ~ E'^\d+$' THEN $filter_label_column::integer ELSE $filter_label_column END"),
    'label'
])
->group($filter . "_$pk_location_group_type", [
    DB::raw("CASE WHEN $filter_label_column ~ E'^\d+$' THEN $filter_label_column::integer ELSE $filter_label_column END")
])
->order('label', 'asc');

      This code uses a regular expression to check if the value is numeric before casting it to an integer.

    By trying these approaches and examining the data and SQL queries, you should be able to cast the field as an integer effectively and get the desired results.

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  2. 0

    It appears that you wish to cast a column in your PostgreSQL query to an integer in order to receive the data in a numeric format, but the example code makes use of PHP’s SQL construction tools rather than actually performing the query. The correct way to cast a column in PostgreSQL to an integer is as follows:

    case 'location_group':
    $filter_label_column = 'location_group_' . $pk_location_group_type . '_name';

    if (!is_missing_or_empty($request['params'], 'filter_label')) {
        $filter_label_column = 'location_group_' . $pk_location_group_type . '_' . $request['params']['filter_label'];
    }

    $query->select([
        $filter . "_$pk_location_group_type",
        'pk'
    ], [
        "CAST($filter_label_column AS INTEGER)",
        'label'
    ])->group($filter . "_$pk_location_group_type", "CAST($filter_label_column AS INTEGER)")
    ->order('label', 'asc');
    break;

    You’ve used the CAST function to cast the $filter_label_column to an integer in this code, which is correct. Use AS INTEGER for the casting rather than AS SIGNED, though.

    Verify that the information in the $filter_label_column is actually a string that can be cast to an integer if the results of this function don’t match what was anticipated. You may need to handle non-integer numbers differently if they are present in the column, for as by filtering them out or setting a default value in the case of non-integer values.

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