Dynamically set values into "this" in typescript class constructor

Question

Here is a simplified class. I try to loop over key values in constructor, to dynamically assign values to this. But it doesn't work. Is it a syntax problem ? Or is it not possible ?

class DirectoryModel {

    public link_title: string
    public link_desc: string

    constructor(fields: any) {
        console.log(fields) // ok
        _.forOwn(fields, function (value, key) {
            console.log(key) // ok
            console.log(value) // ok
            this[key] = value // "Cannot set property 'link_title' of undefined"
        })

       // this.link_title = fields.link_title
       // this.link_desc = fields.link_desc
    }
}

Don't you need the bind that function? Otherwise its this will probably be window. — yelsayed
– yelsayed, Commented May 4, 2016 at 11:13

Alex · Accepted Answer · 2016-05-04 11:16:48Z

1

As Yasser commented, this is not bound to your DirectoryModel. Use arrow functions to bind this to your instance:

class DirectoryModel
{

    public link_title: string
    public link_desc: string

    constructor(fields: any)
    {
        _.forOwn(fields, (value, key) => //This binds `this`
        {
            this[key] = value
        })
    }
}

answered May 4, 2016 at 11:16

Alex

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