Form2json is a decoder for x-www-form-urlencoded data that supports complex structures. It uses simple dot-notation for nested properties and square brackets to denote arrays.

Syntax

Here are some examples to illustrate the syntax.

Nested Objects

The following string represents a nested object:

planet.name=Mars&planet.diameter=0.532

The string will be decoded as:

{
    planet: {
        name: "Mars",
        diameter: 0.532
    }
}

There are no restrictions on the nesting-level:

planet.mars.diameter=0.532&planet.mars.mass=0.11

{
    planet: {
        mars: {
            diameter: 0.532,
            mass: 0.11
        }
    }
}

Arrays

Arrays can be encoded using square brackets:

planets[0]=Venus&planets[1]=Earth&planets[2]=Mars

{
    planets: ["Venus", "Earth", "Mars"]
}

If the index is omitted, form2json will push the values to the array in order of appearance:

planets[]=Mars&planets[]=Venus&planets[]=Earth

{
    planets: ["Mars", "Venus", "Earth"]
}

This feature is really useful, as it allows you to re-order the input fields on the client, without having to update the field names. In order to use this feature with arrays containing nested objects, we have to use a slightly different syntax:

planets[$2].name=Mars&planets[$2].mass=0.11&planets[$0].name=Venus&planets[$0].mass=0.82&planets[$1].name=Earth&planets[$1].mass=1

{
    planets: [
        { name: "Mars", mass: 0.11 },
        { name: "Venus, mass: 0.82 },
        { name: "Earth", mass: 1 }
    ]
}

In fact you may use any non-numerical value as index. All items having the same index will be grouped into one object.