title: React Native navigation param doesn't get updated value
body: <p>I have a React Native application where i'm taking input from one component and sending the input values as navigation params to other component where search is performed according to those input data. Now, it's working on first time when i'm getting the input values from receiving them with <code>navigation.getParam</code>.But when i go back to add some new inputs and go to the other component <code>navigation.getParam</code>shows the older value not the current one. Here's where i'm taking the inputs:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>inputData = () =&gt; {
      let bodyData = {
        customer_id: this.state.customerId,
        security_code: this.state.userSecurityCode,
        vendor: this.state.vendor,
        category_id: this.state.categoryName,
        country_id: this.state.countryName,
        zone_id: this.state.zoneName,
        navigationIdentity: 1
      }
        this.props.navigation.navigate('Vendor',bodyData)
    }</code></pre>
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  </p>
  
  <p>And here's i'm receiving:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code> componentWillMount() {
      const { navigation } = this.props;
      this.focusListener = navigation.addListener("didFocus", () =&gt; {
        const customer_id = navigation.getParam('customer_id')
        const security_code = navigation.getParam('security_code')
        const vendor = navigation.getParam('vendor')
        const category_id = navigation.getParam('category_id')
        const country_id = navigation.getParam('country_id')
        const zone_id = navigation.getParam('zone_id')
        let searchBody = {
          customer_id: customer_id,
          security_code: security_code,
          vendor: vendor,
          category_id: category_id,
          country_id: country_id,
          zone_id: zone_id
        }
        console.log('in focus',searchBody)
      });
    }</code></pre>
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  <p>Now the <code>console.log</code> here only shows the first input values received with <code>navigation.getParam</code>. After that when i update input values and navigate it still shows the first fetched values.</p>