无法在循环中访问Lavavel集合属性

Question

I am trying to access a collection and create a new object using part of the results.

I keep getting this Undefined offset: 0 and I can't seem to get around it.

Here is my foreach loop in my controller;

foreach($payments as $payment_key => $payment_value) {

        //payment_value['Vendor ZIP'] will be something like "SW1A1AA"
        $partial_vendor_zip = trim_and_convert($payment_value['Vendor ZIP'], 0, -3);

        //$partial_vendor_zip will be something like "SW1A"         
        //SQL is something like SELECT * FROM postcode_coord WHERE postcode = 'SW1A' LIMIT 1;
        $postcode_coord = PostcodeCoord::where('postcode', '=', $partial_vendor_zip)->take(1)->get();

        print $postcode_coord['0']->lat; //causes error; Undefined offset: 0

        $markers[] = (object)[
            "postcode" => $postcode_coord->postcode,
            "payment_name" => $payment_value['Contract Title'],
            "full_postcode" => $payment_value['Vendor ZIP'],
            "lat" => $postcode_coord->lat,
            "lng" => $postcode_coord->lng,
        ];

    }

Interestingly, I can still get a print of all the "lat"s - but I also get the error. If I replace that with just a print_r($postcode_coord); then here is a sample of my collection;

Illuminate\Database\Eloquent\Collection Object
(
[items:protected] => Array
    (
        [0] => App\Models\PostcodeCoord Object
            (
                [connection:protected] => 
                [table:protected] => 
                [primaryKey:protected] => id
                [perPage:protected] => 15
                [incrementing] => 1
                [timestamps] => 1
                [attributes:protected] => Array
                    (
                        [id] => 429
                        [postcode] => CF11
                        [lat] => 51.47
                        [lng] => -3.20
                        [created_at] => 2015-02-20 13:07:01
                        [updated_at] => 2015-02-20 13:07:01
                    )

                [original:protected] => Array
                    (
                        [id] => 429
                        [postcode] => CF11
                        [lat] => 51.47
                        [lng] => -3.20
                        [created_at] => 2015-02-20 13:07:01
                        [updated_at] => 2015-02-20 13:07:01
                    )

                [relations:protected] => Array
                    (
                    )

                [hidden:protected] => Array
                    (
                    )

                [visible:protected] => Array
                    (
                    )

                [appends:protected] => Array
                    (
                    )

                [fillable:protected] => Array
                    (
                    )

                [guarded:protected] => Array
                    (
                        [0] => *
                    )

                [dates:protected] => Array
                    (
                    )

                [casts:protected] => Array
                    (
                    )

                [touches:protected] => Array
                    (
                    )

                [observables:protected] => Array
                    (
                    )

                [with:protected] => Array
                    (
                    )

                [morphClass:protected] => 
                [exists] => 1
            )

    )

)

So that works! But I can't reference the attributes. Even when I try and change my query to something like;

$postcode_coord = PostcodeCoord::where('postcode', '=', $partial_vendor_zip)->take(1)->toArray();

And that just gives me an undefined method error.

Laravel is very confusing to me...

Answer 1

You need to do it like this:

$postcode_coord = PostcodeCoord::where('postcode', '=', $partial_vendor_zip)->first();

print $postcode_coord->lat;

$markers[] = (object)[
    "postcode" => $postcode_coord->postcode,
    "payment_name" => $payment_value['Contract Title'],
    "full_postcode" => $payment_value['Vendor ZIP'],
    "lat" => $postcode_coord->lat,
    "lng" => $postcode_coord->lng,
];

Note the use of first() instead of take(1)->get() , since the latter will return a collection and the former will return a single item.

If you really want to use take(1)->get() , then you have to do it like this:

$postcode_coord = PostcodeCoord::where('postcode', '=', $partial_vendor_zip)->take(1)->get();

print $postcode_coord[0]->lat;

$markers[] = (object)[
    "postcode" => $postcode_coord[0]->postcode,
    "payment_name" => $payment_value['Contract Title'],
    "full_postcode" => $payment_value['Vendor ZIP'],
    "lat" => $postcode_coord[0]->lat,
    "lng" => $postcode_coord[0]->lng,
];

Note here the use of 0 instead of '0' and that this index is also used in subsequent references to $postcode_coord .