title: Simply watching/reading a value from Apollo cache
body: <p>I am trying to perform what I believe is a simple task. I have a search box that is successfully using the client.writeQuery to add an item to the cache.It looks like this:</p>
  
  <pre><code>client.writeQuery({
          query: gql`
              {
                  searchQuery {
                      query
                  }
              }
          `,
          data: {
              searchQuery: {
                  query: event.target.value,
                  __typename: 'searchQuery'
              }
          }
      });
  </code></pre>
  
  <p>This works as intended as I can use the Apollo Chrome tools and see it getting set and updated in the cache as I type. This is not a value I am needing to keep in the database.</p>
  
  <p>All I want to do with this is have it read by another component and use it in a query. I've looked over tons of documentation and tutorials but not seem to be very concise or clear to me. I have another component that has a Query component that takes that string and uses it to search. I also know this works properly because before I was using Apollo Link State I was just having it use a value in the React state.</p>
  
  <p>How can I get this React component to watch and use this Apollo cache value in the same way it was using the React state? The subsequent component just looks like this:</p>
  
  <pre><code>const MainSearchQuery = ({searchQuery}) =&gt; (
      &lt;Query query={MAIN_QUERY} variables={{searchQuery}}&gt;
          {({loading, error, data}) =&gt; {
              if (loading) return(
                  &lt;p&gt;Finding something ...&lt;/p&gt;
              );
  
              if (error) return (
                  &lt;p&gt;Ah man! There was nothing to find.&lt;/p&gt;
              );
  
              return (
                  &lt;MainSearchResults searchResults={data.ResultsBySubstring} /&gt;
              );
          }}
      &lt;/Query&gt;
  );
  </code></pre>
  
  <p>The Query component that calls MAIN_QUERY just passes the returned data to a component in charge of rendering the results. Any help would be greatly appreciated as this small issue that I imagine is simple to solve has slowed by progress of learning Apollo/GraphQL to a halt. Thanks.</p>