Insert a key:value pair into an array based on another key:value pair
2

Question

Insert a key:value pair into an array based on another key:value pair

waubain (TechnicalUser)

(OP)

3 Apr 19 14:14

I am trying to insert a key:value pair into an array based on another key:value pair. The json array is in a text file. I am not getting any errors, but nothing is inserted. After insertion it should look like the first array. The key and new value comes from a form.

Here is the array meetinfo_arrayTest.txt

CODE -->

[{"meetdate":"2019-03-23","topic":"Hypertension", "handout":"htn"},
 {"meetdate":"2019-04-18","topic":"TBA"},
 {"meetdate":"2019-05-02","topic":"TBA"}]

Here is my code.

CODE --> php

//retrieve values from form
	$meetdate = $form->getValue('meetdate');                
        $acronym = $form->getValue('ho_acronym');

        //Retrieve the data from our text file.
        $fileContents = file_get_contents('../editor/textfiles/meetinfo_arrayTest.txt');

        //Convert the JSON string back into an array.
        $infodecoded = json_decode($fileContents, true);
         
        foreach($fileContents as $row) {
        	if (($row['meetdate']) == $meetdate) {
                	$row['handout'] = $acronym; 
                }}
                    
        //Save the JSON string to a text file.
        $infoencoded = json_encode($infodecoded);
        file_put_contents("../editor/textfiles/meetinfo_arrayTest.txt", $infoencoded);

Any help would be appreciated.

feherke (Programmer) · Answer 1 · 2019-04-03 15:01:36

Hi

$row holds a copy of current array item. Modifying it does not affect $fileContents. So better explicitly change the array :

CODE --> PHP ( fragment )

foreach ($fileContents as $nr => $row) {
    if (($row['meetdate']) == $meetdate) {
        $fileContents[$nr]['handout'] = $acronym; 
    }
}

Alternatively you can change $row into reference, but that is not recommended practice as later reuse of $row after the loop will still alter the last referred item :

CODE --> PHP ( fragment )

foreach ($fileContents as &$row) {
    if (($row['meetdate']) == $meetdate) {
        $row['handout'] = $acronym; 
    }
}

Of course, Unsetting References helps to avoid future surprises.

Feherke.
feherke.github.io

waubain (TechnicalUser) · Answer 2 · 2019-04-04 11:43:50

RE: Insert a key:value pair into an array based on another key:value pair

waubain (TechnicalUser)

(OP)

4 Apr 19 11:43

Thanks for your help.

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Insert a key:value pair into an array based on another key:value pair
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