When using loopback API, is 'AND' operator redundant in 'where' filter with multiple conditions? For example, I tested the following two queries and they return the same result:
<model>.find({ where: { <condition1>, <condition2> } });
<model>.find({ where: { and: [<condition1>, <condtion2>] } });
To be more specific, suppose this is the table content:
name value
---- -----
a 1
b 2
When I execute 'find()' using two different 'where' filters, I get the first record in both cases:
{ where: { name: 'a', value: 1 } }
{ where: { and: [ { name: 'a'}, { value: 1 } ] } }
I've read through the API documents, but didn't find what logical operator is used when there are multiple conditions. If 'AND' is redundant as shown in my test, I prefer not using it. But I just want to make sure if this is true in general, or if it just happens to work with postgreSQL which I'm using.
This is a valid query which could only be accomplished with an and statement.
{
"where": {
"or": [
{"and": [{"classification": "adn"}, {"series": "2"}]},
{"series": "3"}
]
}
}
EDIT: https://github.com/strongloop/loopback-filters/blob/master/index.js
function matchesFilter(obj, filter) {
var where = filter.where;
var pass = true;
var keys = Object.keys(where);
keys.forEach(function(key) {
if (key === 'and' || key === 'or') {
if (Array.isArray(where[key])) {
if (key === 'and') {
pass = where[key].every(function(cond) {
return applyFilter({where: cond})(obj);
});
return pass;
}
if (key === 'or') {
pass = where[key].some(function(cond) {
return applyFilter({where: cond})(obj);
});
return pass;
}
}
}
if (!test(where[key], getValue(obj, key))) {
pass = false;
}
});
return pass;
}
It iterates through the keys of the where object where looking for failure, so it acts like an implicit and statement in your case.
The loopback datasource juggler contains tests which use the implicit and format
{PictureLink.findOne({where: {pictureId: anotherPicture.id, imageableType: 'Article'}},
{pictureId: anotherPicture.id, imageableId: article.id, imageableType: 'Article',}