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feat: add unique index support on create for in-memory connector #1672

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feat: add unique index support on create for in-memory connector #1672

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6400ebe
feat: add unique index support on create for in-memory connetor
Dec 6, 2018
3342718
fixup! apply feedback
Dec 6, 2018
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15 changes: 15 additions & 0 deletions lib/connectors/memory.js
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Original file line number Diff line number Diff line change
Expand Up @@ -255,6 +255,21 @@ Memory.prototype._createSync = function(model, data, fn) {
this.collection(model, {});
}

var indexes = this._models[model].model.definition.indexes();
for (var idx in indexes) {
var idxPropName = idx.substring(0, idx.indexOf('_index'));
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I find this string manipulation hacky and fragile. Let's fix definition.indexes() to copy the property name into index definition.

const idxPropName = indexes[idx].keys[0];

if (indexes[idx].unique === true) {
for (var instId in this.cache[model]) {
var inst = JSON.parse(this.cache[model][instId]);
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This implementation will scale poorly. When there are 1000 records, you have to JSON parse 1000 records to check for uniqueness. That's a lot of CPU work!

IMO, UNIQUE INDEX should be implemented using a Set:

  • when creating a new record, add the property value into the Set
  • when deleting a record, remove it's property value from the Set
  • when updating a record, remove the old property value and add the new property value

Whenever adding a new property value, report an error if the property value already exists in the Set.

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The reason I have to use JSON parse is because we stringify the model instances to store in the cache :(. However, I like that approach and I'm trying it out. I think it will work well with multiple-key unique indexes too.

if (inst[idxPropName] === data[idxPropName]) {
var duplicateIndexError = new Error(g.f('Duplicate entry for %s.%s', model, idxPropName));
duplicateIndexError.statusCode = duplicateIndexError.status = 409;
return fn(duplicateIndexError);
}
}
}
}

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Please use https://github.com/strongloop/loopback-datasource-juggler/blob/master/lib/model-definition.js#L194

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Good catch!

if (this.collection(model)[id]) {
var error = new Error(g.f('Duplicate entry for %s.%s', model, idName));
error.statusCode = error.status = 409;
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18 changes: 18 additions & 0 deletions test/memory.test.js
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Expand Up @@ -677,6 +677,24 @@ describe('Memory connector', function() {
});
});

it('should refuse to create object with duplicate unique index', function(done) {
var ds = new DataSource({connector: 'memory'});
var Product = ds.define('ProductTest', {name: {type: String, index: {unique: true}}}, {forceId: false});
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{name: {type: String, index: {unique: true}}}

I see this is an existing & already documented syntax 👍

https://loopback.io/doc/en/lb3/Model-definition-JSON-file.html#indexes

I find this statement as too long & difficult to read when on a single line, could you please split it into multiple lines (e.g. using "one arg per line" rule).

ds.automigrate('ProductTest', function(err) {
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juggler v4 requires Node.js 8+. In new code, we should stop using callbacks and use async/await instead.

In #1671, I am fixing eslint config to allow async functions.

if (err) return done(err);

Product.create({name: 'a-name'}, function(err, p) {
if (err) return done(err);
Product.create({name: 'a-name'}, function(err) {
should.exist(err);
err.message.should.match(/Duplicate/i);
err.statusCode.should.equal(409);
done();
});
});
});
});

describe('automigrate', function() {
var ds;
beforeEach(function() {
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