Conditions Builder

The conditions builder allows you to create condition expression with logical operators such AND and OR. The first argument (or left operand) will be by default considered as a pointer. The second argument is an SQL operator which will allows you to perform an actual comparison. The third argument is a value by default, which implies that if you want to use a pointer instead, you will need to wrap it within quotes yourself. If you use the condition function with two arguments only (left operand and right operand), the operator will be = (equals).

You can pass a conditions builder to another one (as well as others builders, like a select builder), It this case it will be considered as a sub expression and therefore will be between parentheses. 

sh
    .if('posts.published_at', '>', new Date(2010, 1, 1))
    .and('title', 'foo')
    .or(sh.if('posts.user_id', 'IN', sh.select('user_id').from('users')))
    .build();

// > { text:
//    `"posts"."published_at" > '2010-02-01T05:00:00.000Z' AND
//      "title" = 'foo' OR ("posts"."user_id" IN (SELECT "user_id" FROM "users"))`,
//   values: [] }

Factories

There are different ways to create a conditions builder. You can use the if factory like in the example above. This case will likely occur when you want to create a sub expression to pass to another condition builder.

The second way will occur more often. It is by calling a method of a builder which returns a proxied conditions builder: select.where or select.on are good examples. Using a proxy let you conveniently call the conditions builder methods as if they were part of the main builder. Whenever a method or a property which does not belong to the conditions builder is called, the proxy is revoked. 

const Laurents = sh
    .select('user_id')
    .from('users')
    .where('first_name', 'Laurent')
    .noop(); // call noop !!!

sh
    .select()
    .from('posts')
    .where('user_id', 'IN', Laurents)
    .build();

// > { text:
//    `SELECT * FROM "posts" WHERE "user_id" IN
//     SELECT "user_id" FROM "users" WHERE "first_name" = 'Laurent')`,
//   values: [] }

A conditions builders has only two methods for the basic logical operators: .or and .and

If you want to pass around a builder (as argument of a function for example) you should make sure every proxy is revoked first by calling the noop method, otherwise it will definitely lead to some bugs.