Views EVI (Exposed Value Injector)

This is the documentation for the Views EVI (Exposed Value Injector) module.

We will start with a canonical example for site-builders.

What is the problem that this module wants to solve?

There are things we can do with exposed filters that we can't do with contextual filters, like:
* Use "or" with them
* Use "<" or ">"

## TODO: Refactor the rest of the page to match the above. ##
(The use case below is valid, but not the biggest pain spot.)

Sometimes, there is a conflict between the contextual filter (supplied via the URL) and the exposed filter (supplied by a form in a view).

This screenshot shows a view of 10 nodes:
- contextual filter is set to "Content: Nid"
- exposed filter is set to "Content: Nid"

In the screenshot, no results are displayed, because of a conflict between the contextual filter (6) and the exposed filter (3)

A common thing that we would like to achieve is the following:

If no contextual filter is supplied on the url:
- we get all nodes displayed
- the exposed filter is displayed
If we have a contextual filter supplied on the url:
- the value of the exposed filter is set to the contextual filter value
- the exposed filter is hidden

Let's see how we can do this with the Views EVI module.

Install and enable the Views EVI module.

[At least in D8]: Enable "Views EVI" under "Display Extenders" in the Advanced Views Settings (/admin/structure/views/settings/advanced), you can get there fast by following the Configure link next to the module entry in the Modules list.

Important. Replace the Contextual Filter in your view with the "Global: Null" filter, so that the only Contextual Filter you have is "Global: Null".

What does "Global: Null" mean? Well, it's a contextual filter which (by itself) does nothing. We will use the Views EVI module so that its value gets injected into the exposed filter.

Under "Filter Criteria", add a new filter. Select the field you want to match with the contextual filter and check the option "Expose this filter...".

In the views UI, under Advanced > Other, you will find the following options:
- Views EVI: Plugins
- Views EVI: Settings

For "Views EVI: Plugins", apply the following options to the "Nid" exposed filter:
Value: Value with tokens
Visibility: Visible if no value

For "Views EVI: Settings", apply the following options to the "Nid" exposed filter:
Filter value: !1
Visibility inhibiting value: !1

Save the view.

Now, when we have no contextual filter on the URL, the exposed form is available.

However, if there is a contextual filter on the URL, then the exposed form is hidden.