Getting names/values of multiple properties [closed]

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Lets say I have one method, which extracts property name and value:

public TModel Get (Expression<Func<object>> param)
{
 using (OracleConnection connection = new OracleConnection(GetConnectionString()))
 {
 connection.Open();
 var propertyName= ((MemberExpression)param.Body).Member.Name;
 var value = param.Compile()();
 // GetTableName() returns table name of TModel
 var query = $"SELECT * FROM {GetTableName()} WHERE {propertyName}='{value}'";
 var output = connection.Query<TModel>(query);
 connection.Dispose();
 return output.FirstOrDefault();
 }
}

and using it as:

var model = Get(() => foo.FirstProperty);

However, if I want to get name and value from the unknown number of properties, I do this:

public TModel Get(params Expression<Func<object>>[] param)
 using (OracleConnection connection = new OracleConnection(GetConnectionString()))
 {
 connection.Open();
 var query = new StringBuilder();
 query.Append($"SELECT * FROM {GetTableName()} WHERE ");
 for (int i = 0; i < param.Length; i++)
 {
 var propertyName = ((MemberExpression)param[i].Body).Member.Name;
 var value = param[i].Compile()();
 query.Append($"{propertyName} = '{value}'");
 if (i + 1 < param.Length) query.Append(" AND ");
 }
 var output = connection.Query<TModel>(query.ToString());
 connection.Dispose();
 return output.FirstOrDefault();
 }
 }

But, implementation looks a bit 'ugly' and verbose:

var model = Get(() => foo.FirstProperty, () => foo.SecondProperty); // and so on

I could send manualy name of the property + value, however, I would like to keep the implementation as simple as possible and less verbose.

Is there any way to simplify this?

• BCdotWEB: Pseudocode, stub code, hypothetical code, obfuscated code, and generic best practices are outside the scope of this site. Please follow the tour, and read "What topics can I ask about here?", "How do I ask a good question?" and "What types of questions should I avoid asking?".
• BCdotWEB: Also, what is even the point of this code? In what scenario do you know so little of your DB that you're trying to guess what fields a table has? Surely you're not building your own ORM? If so: lostechies.com/jimmybogard/2012/07/24/dont-write-your-own-orm .
• Eduardas Šlutas: @BCdotWEB This is not hypothetical, obfuscated code and I'm not looking for best practices. Main point of this question is how to simplify method to get name/value pairs of multiple properties. And building a dynamic sql statement is not the same as creating own ORM. Reason behind: I'm using dapper.Contrib extention and Oracle database. However, these two are not very 'friendly', therefore, I have a method which writes sql statement based on the given object and then pass it to the dapper, which does all the ORM job.
• iSR5: how about passing object[] which would be something like Get(() => new {foo.FirstProperty, foo.SecondProperty}) then just loop over the object array.
• yob: aside from other comments, why do you invoke " connection.Dispose()" if you're enclosing in "using"?

Answer 1

If you want to iterate through all of the properties then reflection will help you to do that. You can find more at MS docs Something like this:

public TModel Get<TParam>(TParam param)
{
 var allParams = typeof(TParam).GetProperties().Select(p => $"{p.Name} ='{p.GetValue(param)}'");
 var condition = string.Join(" AND ", allParams);
 using (OracleConnection connection = new OracleConnection(GetConnectionString()))
 {
 connection.Open();
 // GetTableName() returns table name of TModel
 var query = $"SELECT * FROM {GetTableName()} WHERE {condition}";
 var output = connection.Query<TModel>(query);
 return output.FirstOrDefault();
 }
}

But you have to think how to escape SQL injections. Because the value of query variable in current implementation could have potential vulnerabilities.