需要帮助解析JSON输出

Question

I'm making a REST call in PHP and returning JSON. I'm eventually putting this into tables, but trying to output the value for now to get the hang of it.

There are values in the "data" field I would like to get into variables. In my example they would be "201807", 23.43 and "201806", 22.54 . It's the first two values of the property "data"

My code looks like this:

<?php

$service_url = "http://api.eia.gov/geoset/?geoset_id=ELEC.PRICE.RES.M&regions=USA-AL,USA-AK,USA-AR&api_key=3a8b92cfaf3a21e2e990f228c9152eeb&out=json&start=2018";

$get_data = callAPI('GET', $service_url, false);
$response = json_decode($get_data);

foreach ($response as $r) {
        echo $row->name;
        echo $row->geoset_id;
}

?>

And JSON looks like this:

{
    "geoset": {
        "geoset_id": "ELEC.PRICE.RES.M",
        "setname": "Average retail price of electricity : residential : monthly",
        "f": "M",
        "units": "cents per kilowatthour",
        "unitsshort": null,
        "series": {
            "USA-AK": {
                "series_id": "ELEC.PRICE.AK-RES.M",
                "name": "Average retail price of electricity : Alaska : residential : monthly",
                "region": "USA-AK",
                "latlon": null,
                "unitsshort": null,
                "start": "200101",
                "end": "201807",
                "data": [
                    ["201807", 23.43],
                    ["201806", 22.54],
                    ["201805", 22.16],
                    ["201804", 21.61],
                    ["201803", 21.47],
                    ["201802", 21.11],
                    ["201801", 21.67]
                ]
            },
            "USA-AL": {
                "series_id": "ELEC.PRICE.AL-RES.M",
                "name": "Average retail price of electricity : Alabama : residential : monthly",
                "region": "USA-AL",
                "latlon": null,
                "unitsshort": null,
                "start": "200101",
                "end": "201807",
                "data": [
                    ["201807", 12.28],
                    ["201806", 12.41],
                    ["201805", 12.49],
                    ["201804", 12.79],
                    ["201803", 12.65],
                    ["201802", 12.29],
                    ["201801", 11.59]
                ]
            },
            "USA-AR": {
                "series_id": "ELEC.PRICE.AR-RES.M",
                "name": "Average retail price of electricity : Arkansas : residential : monthly",
                "region": "USA-AR",
                "latlon": null,
                "unitsshort": null,
                "start": "200101",
                "end": "201807",
                "data": [
                    ["201807", 9.98],
                    ["201806", 9.99],
                    ["201805", 9.89],
                    ["201804", 10],
                    ["201803", 10.47],
                    ["201802", 9.8],
                    ["201801", 9.36]
                ]
            }
        }
    }
}

So far I'm getting NULL values back.

Answer 1

As you have used json_decode your result will be convert to object type. so you should do as follows:

$geoset = $response->geoset; 
$geosetid = $geoset->geoset_id; 

foreach ($geoset->series as $row) {
   echo $row->name;
   $data = $row->data; //this will produce the values as array
}

Your data array will be like this:

Array
(
    [0] => Array
        (
            [0] => 201807
            [1] => 23.43
        )

    [1] => Array
        (
            [0] => 201806
            [1] => 22.54
        )
)
...

Hopefully this helps! :)

Answer 2

Your code will never work, because:

• You iterate $response as $r , but use $row inside;
• The $response has only one child: geoset . There is no $response->name neither $response->geoset_id .

If you want the geoset_id , you must access using: $response->geoset->geoset_id .

To achieve this:

There are values in the "data" field I would like to get into variables

Use the following code:

foreach ($response->geoset->series as $series) {
    foreach ($series->data as $data) {
        $date = $data[0];
        $value = $data[1];
    }
}