PHP-CRUD-API now has transforms!

Last week I created a new GitHub project called “PHP-CRUD-API” and it allows you to quickly setup a simple REST API with CRUD functionality by just adding a single “api.php” file to your project and configuring it’s database connection. Today I show how the relational support of this project works.

Supported table relations

There are three types of table relations supported:

• BelongsTo
• HasMany
• HasAndBelongsToMany

Blog example

When you use the “list” command of the API it allows you to specify multiple tables. If these tables have relations (foreign keys) the output will be filtered in such a way that only relevant records are returned. This is what the API outputs when you list posts and comments filtered on a specific post:

{
    "posts": {
        "columns": [
            "id",
            "user_id",
            "category_id",
            "content"
        ],
        "records": [
            [
                "1",
                "1",
                "1",
                "blog started"
            ]
        ]
    },
    "comments": {
        "relations": {
            "post_id": "posts.id"
        },
        "columns": [
            "id",
            "post_id",
            "message"
        ],
        "records": [
            [
                "1",
                "1",
                "great"
            ],
            [
                "2",
                "1",
                "fantastic"
            ]
        ]
    }
}

Not so useful right? You would probably like to see something like this:

{
    "posts": [
        {
            "id": "1",
            "comments": [
                {
                    "id": "1",
                    "post_id": "1",
                    "message": "great"
                },
                {
                    "id": "2",
                    "post_id": "1",
                    "message": "fantastic"
                }
            ],
            "user_id": "1",
            "category_id": "1",
            "content": "blog started"
        }
    ]
}

That is exactly what the function “php_crud_api_transform()” does. You run this function on the client after receiving the API response. This is beneficial as it uses the CPU and RAM of the API consumer instead of that of the API server. This transformation function is implemented in PHP and JavaScript, so that you can make spiders and users with browsers equally happy!

<?php
function php_crud_api_transform(&$tables) {
	$getobjs = function(&$tables,$table_name,$where_index=false,$match_value=false) use (&$getobjs) {
		$objects = array();
		foreach($tables[$table_name]['records'] as $record) {
			if ($where_index===false || $record[$where_index]==$match_value) {
				$object = array();
				foreach ($tables[$table_name]['columns'] as $index=>$column) {
					$object[$column] = $record[$index];
					foreach ($tables as $relation=>$reltable) {
						foreach ($reltable['relations'] as $key=>$target) {
							if ($target == "$table_name.$column") {
								$columnidx = array_flip($reltable['columns']);
								$object[$relation] = $getobjs($tables,$relation,$columnidx[$key],$record[$index]);
							}
						}
					}
				}
				$objects[] = $object;
			}
		}
		return $objects;
	};
	$tree = array();
	foreach ($tables as $name=>$table) {
		if (!isset($table['relations'])) {
			$tree[$name] = $getobjs($tables,$name);
		}
	}
	return $tree;
}

And the JavaScript version:

function php_crud_api_transform(tables) {
	var array_flip = function (trans) {
		var key, tmp_ar = {};
		for (key in trans) {
			tmp_ar[trans[key]] = key;
		}
		return tmp_ar;
	};
	var get_objects = function (tables,table_name,where_index,match_value) {
		var objects = [];
		for (var record in tables[table_name]['records']) {
			record = tables[table_name]['records'][record];
			if (!where_index || record[where_index]==match_value) {
				var object = {};
				for (var index in tables[table_name]['columns']) {
					var column = tables[table_name]['columns'][index];
					object[column] = record[index];
					for (var relation in tables) {
						var reltable = tables[relation];
						for (var key in reltable['relations']) {
							var target = reltable['relations'][key];
							if (target == table_name+'.'+column) {
								column_indices = array_flip(reltable['columns']);
								object[relation] = get_objects(tables,relation,column_indices[key],record[index]);
							}
						}
					}
				}
				objects.push(object);
			}
		}
		return objects;
	};
	tree = {};
	for (var name in tables) {
		var table = tables[name];
		if (!table['relations']) {
			tree[name] = get_objects(tables,name);
		}
	}
	return tree;
}

Check out all the source code on my GitHub account: https://github.com/mevdschee/php-crud-api

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