Weighted Reaction System 2.0 implementation

[antonkomarev]

Part of #85

To Do

• Add rate attribute to Reaction model
• Add getRate method to Reaction model
• Change weight attributes type to float
• Change getWeight methods return type to float
• Change incrementWeight methods argument type to float
• Change decrementWeight methods argument type to float
• Change love_reactant_reaction_counters.weight db column type to decimal(13, 2)
• Change love_reactant_reaction_totals.weight db column type to decimal(13, 2)
• Change love_reactions.weight db column type to decimal(4, 2)
• Add $rate argument to reactTo method
• Allow to change reaction rate
• Add $rate to Reactant::isReactedBy method
• Add $rate to Reactant::isNotReactedBy method
• Add $rate to Reacter::hasReactedTo method
• Add $rate to Reacter::hasNotReactedTo method
• Test for love_reactions.rate db column min value
• Test for love_reactions.rate db column max value
• Write about min\max values in documentation

Min\Max Values

• Reaction::RATE_MIN = 0.01
• Reaction::RATE_MAX = 99.99
• ReactionCounter::WEIGHT_MIN = -99999999999.99
• ReactionCounter::WEIGHT_MAX = 99999999999.99
• ReactionTotal::WEIGHT_MIN = -99999999999.99
• ReactionTotal::WEIGHT_MAX = 99999999999.99

I decided not to create constants for ReactionCounter & ReactionTotal weight ranges for now. They are computed automatically and it's nearly to impossible to reach the limits in near future.

How did I calculated this decimal value?

If we will take the most popular YouTube video with 40 000 000+ likes multiply this value by 99.99 (RATE_MAX) we will receive ~4 000 000 000 total weight (10 digits). Because decimals are stored using a binary format that packs nine decimal digits into 4 bytes, then we will have 2 packs for integer part (9 + 1) which will require 4 bytes + 1 byte. But +1 digit wouldn't add extra byte because 1-2 digits have same size of 1 byte, so we could start with 11 digits on the integer part and 2 digits on fractional part.

• DECIMAL(4, 2) require 2 + 1 = 3 bytes
• DECIMAL (13, 2) require 4 + 1 + 1 = 6 bytes

A decimal type can store a Maximum of 65 Digits values, with 30 digits after decimal point. This is another one reason why I decided not to add range limits for counters. You are free to modify your database columns and extend or reduce weight range without touching codebase.

[antonkomarev]

$reaction->getAttributeValue('rate') === $rate

Need to use Reaction contract.

Variant 1

$reaction->getRate() === $rate

I think it's better stop on this variant because this accessor will be useful for the statistics too.

Variant 2

$reaction->hasRate($rate)

[antonkomarev]

Automated DB Schema changes like love_reaction_types.weight column requires doctrine/dbal to be installed:

$ composer require doctrine/dbal

[antonkomarev]

We can add 3rd property ?float $rate to these Models & Facades methods:

• Reactant::isReactedBy
• Reactant::isNotReactedBy
• Reacter::hasReactedTo
• Reacter::hasNotReactedTo

Use Case 1

Send notification to support team leads when user reacted with minimum rate to conversation with support manager.

$reactant->isReactedBy($reacter, $reactionType, $rate)

It will check if $reacter reacted to this $reactant with exact $reactionType and $rate amount.

Use Case 2

Open access to restricted application area to users who reacted with maximum rate to our post.

$reactant->isReactedBy($reacter, null, $rate)

It will check if $reacter reacted to this $reactant regardless of the $reactionType but with exact $rate amount.