Validator_Doc.md

Simple validator:

Simple validator allows checks in a context of a single task. For example check that dns name is valid.

1. Create a new class derived from the MIGA.Sitecore9Installer.Validation.Validators.BaseValidator
2. Implement IEnumerable<ValidationResult> GetErrorsForTask(Task task, IEnumerable<InstallParam> paramsToValidate) method. Implementation details are explained later.
3. Add validator definition to the GlobalParamsConfig\Validators.json file:

    "ValidatorDefinitions": [   
    {
      "Name": "HostNameValidator",
      "Type": "MIGA.Sitecore9Installer.Validation.Validators.HostNameValidator",
      "Data": { "ParamNames": "DnsName" }
    }
  ]

4. In the ParamNames provide comma separated list of parameter names that should be validated.
5. [optional] Add validator to a list in the GlobalParamsConfig\Validators.json file:

"ValidatorLists": {    
  "Basic": [
    "HostNameValidator",
    "SolrServiceValidator"
  ] 
}

6. Reference validator or validator list in the Global params file. For example for sitecore 9.2.0 XP0 - GlobalParamsConfig\XP\GlobalParams_9.2_XP0.json:

"Validators": [
  "HostNameValidator"
]

for a valitador list:

 "Validators": [
  "list|Basic"
]

GetErrorsForTask method.

The method is invoked for each task that will be executed for the installation. It accepts a Task and a list of InstallParams objects. InstallParams list contains InstallParam objects of the current task which names were provided in the ParamNames. Here you can do the necessary check and return validation result. You can do multiple checks and return a validation result collection:

protected override IEnumerable<ValidationResult> GetErrorsForTask(Task task, IEnumerable<InstallParam> paramsToValidate)
  {
    foreach (InstallParam param in paramsToValidate)
    {
      if (Uri.CheckHostName(param.Value) != UriHostNameType.Dns)
      {
        ValidationResult r = new ValidationResult(ValidatorState.Error,
          string.Format("Invalid host in '{0}' of '{1}'", param.Name, task.Name), null);
        yield return r;
      }
    }
  }

Complex validator

This approach allows for performing cross-task checks. For example, one can check that host of the reporting instance corresponds to the reporting services of other instances.

1. Create a class that implements MIGA.Sitecore9Installer.Validation.IValidator.
2. Implement IEnumerable<ValidationResult> Evaluate(IEnumerable<Task> tasks) and Dictionary<string,string> Data { get; set; }. Data must not return null.
3. Perform steps 3-6 from the simple validator part.

Evaluate method

The method accepts a collection of Task that will be executed for installation and returns a collection of ValidationResult