Get only values from rows and associations with Sequelize - mysql

Question

I am using Sequelize, MySQL and Node to write a web application.
For most of my DB needs, I usually do some verification, then fetch my models (eagerly with associations) and send them back to the client, almost always as-is (at least, up to now).
I wrote a little utility function getValuesFromRows to extract the values from a returned row array:
getValuesFromRows: function(rows, valuesProp) {
// get POD (plain old data) values
valuesProp = valuesProp || 'values';
if (rows instanceof Array) {
var allValues = [];
for (var i = 0; i < rows.length; ++i) {
allValues[i] = rows[i][valuesProp];
}
return allValues;
}
else if (rows) {
// only one object
return rows[valuesProp];
}
return null;
}
// ...
...findAll(...)...complete(function(err, rows) {
var allValues = getValuesFromRows(rows);
sendToClient(errToString(err, user), allValues);
});
However, I am adding more and more complex relations to my DB models. As a result, I get more associations that I have to fetch. Now, I don't only have to call above function to get the values from each row, but also I need more complicated utilities to get the values from all included (eagerly loaded) associations. Is there a way to only get values from Sequelize queries (and not the Sequelize model instance) that also includes all associated values from the instance?
Else, I would have to manually "get all values from each Project and add one item to that values object for the values property of each entry of Project.members" (for example). Note that things get worse fast if you nest associations (e.g. members have tasks and tasks have this and that etc.).
I am guessing that I have to write such utility myself?

Answer 1

I found a simple solution to my problem, by extending my existing POD converting function above with a recursion into all include'd associations of the query. The Solution works with find, findAll, all and possibly other operations with non-trivial results.
Code
/**
* Get POD (plain old data) values from Sequelize results.
*
* #param rows The result object or array from a Sequelize query's `success` or `complete` operation.
* #param associations The `include` parameter of the Sequelize query.
*/
getValuesFromRows: function(rows, associations) {
// get POD (plain old data) values
var values;
if (rows instanceof Array) {
// call this method on every element of the given array of rows
values = [];
for (var i = 0; i < rows.length; ++i) {
// recurse
values[i] = this.getValuesFromRows(rows[i], associations);
}
}
else if (rows) {
// only one row
values = rows.dataValues;
// get values from associated rows
if (values && associations) {
for (var i = 0; i < associations.length; ++i) {
var association = associations[i];
var propName = association.as;
// recurse
values[propName] = this.getValuesFromRows(values[propName], association.include);
};
}
}
return values;
}
Example
var postAssociations = [
// poster association
{
model: User,
as: 'author'
},
// comments association
{
model: Comment,
as: 'comments',
include: [
{
// author association
model: User,
as: 'author'
}
]
}
];
// ...
var query = {
where: ...
include: postAssociations;
};
// query post data from DB
return Post.findAll(query)
// convert Sequelize result to POD
.then(function(posts) {
return getValuesFromRows(posts, postAssociations);
})
// send POD back to client
.then(client.sendPosts);
In the above example, client.sendPosts receives an array. Each entry of the array will have properties author and comments. Each comment in the comments array will also have an author property. The entire array only contains POD (plain old data).