title: Assertion failed: field is String||field is FieldPath||field==FieldPath.documentId "Supported [field] types are [String] and [FieldPath]." Flutter
body: <p>I am trying to read from my firestore database. I am getting this error:</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>Error: Assertion failed: file:///C:/Users/Desktop/flutter/.pub-cache/hosted/pub.dartlang.org/cloud_firestore-3.1.14/lib/src/query.dart:311:7
  field is String || field is FieldPath || field == FieldPath.documentId
  "Supported [field] types are [String] and [FieldPath]."</code></pre>
  </div>
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  </p>
  <p>This is the method ran when trying to read the database:</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>Future ReadUserinDatabase(String email) async {
    DatabaseUser Users = FirebaseFirestore.instance
        .collection('Users')
        .where('Email' == email) as DatabaseUser;
  
    print(Users.UID);
  }</code></pre>
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  </div>
  </p>
  <p>The DatabaseUser class:</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>class DatabaseUser {
    final String CustomerID;
    final String Email;
    final String Role;
    final String Activity;
    final String UID;
  
    DatabaseUser(
        {required this.Email,
        required this.CustomerID,
        required this.Role,
        required this.Activity,
        required this.UID});
  
    Map&lt;String, dynamic&gt; toJson() =&gt; {
          'CustomerID': CustomerID,
          'Email': Email,
          'Role': Role,
          'Activity': Activity,
          'UID': UID
        };
  
    static DatabaseUser fromJson(Map&lt;String, dynamic&gt; json) =&gt; DatabaseUser(
        Email: json['Email'],
        CustomerID: json['CustomerID'],
        Role: json['Role'],
        Activity: json['Activity'],
        UID: json['UID']);
  }</code></pre>
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  </p>
  <p>I need to keep the user to pass the Role and UID so I can display specific things depending on their Role when they log in. Please Help!</p>