php foreach does not take all values from array - php

Question

I'm making a json string which only contains the values which are entered in the form. so far it's going good but the only problem is that the foreach function which makes the string does not take all items from array.
Let's explain something and show my code:
if the $title is not empty I want my final ($content1) string to start with that value. Because it has some other quotes and curlybraces than other values. the same with the date field I also made an if for that because it also contains "date" in it. See my code below:
$title = "fiat titel";
$engine = "1.8";
$day = "1";
$month = "2";
$year = "1999";
$dateBuild = "02/02/1999";
// assoc array push function
function array_push_assoc($array, $key, $value){
$array[$key] = $value;
return $array;
}
$array = array();
if(!empty($title)) {
$array = array_push_assoc($array, 'title', $title);
}
if(!empty($color)) {
$array = array_push_assoc($array, 'field_modelcolor', $color);
}
if(!empty($model)) {
$array = array_push_assoc($array, 'field_carmodel', $model);
}
if(!empty($engine)) {
$array = array_push_assoc($array, 'field_modelengine', $engine);
}
if(!empty($fuel)) {
$array = array_push_assoc($array, 'field_modelfuel', $fuel);
}
if(!empty($day) && !empty($month) && !empty($year)) {
$array = array_push_assoc($array, 'field_modelyear', $dateBuild);
}
$content1 = "";
foreach($array as $ftitle => $value) {
if(empty($content1) && !empty($title)) {
$content1 = ',"' . $ftitle . '":"' . $value . '"';
}
if(!empty($day) && !empty($month) && !empty($year)) {
$content1 = ',"' . $ftitle . '":{"und":[{"value":{"date":"' . $value . '"}}]}';
}
$content1 = ',"' . $ftitle . '":{"und"[{"value":"' . $value . '"}]}';
}
$postContent = '{"type":"carmodels"' . $content1 . '}';
var_dump($array);
echo $postContent;
Right now it's only echo'ing:
{"type":"carmodels","field_modelyear":{"und"[{"value":"02/02/1999"}]}}
And it should be (example):
{"type":"carmodels","field_modelyear":{"und":[{"value":{"date":"02/02/1999"}}]},"field_modelengine":{"und"[{"value":"1.6"}]}}
Thanks in advance!